GENETICS VOCABULARY NAME: DATE: PERIOD: Definitions Genetics: Genetics primer

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1 NAME: DATE: PERIOD: GENETICS VOCABULARY Studying Genetics (the study of DNA and heredity which is the transmission of traits from one generation to another) is valuable because we can predict and understand the likelihood of inheriting particular traits. This helps plant and animal breeders in developing varieties that have more desirable qualities (artificial selection) and Genetics can also help people explain and predict patterns of inheritance in family lines. Definitions Genetics: 1. Genotype: is the actual code that alleles or genes possess (E.g. Tt or TT or tt). The gene may or may not be expressed when you observe a living organism. 2. Phenotype: the observable or detectable characteristics of an individual organism--the observable expression of a genotype. 3. Allele: is an alternate form of a gene for one trait. For example, brown and blue eyes are two different alleles for eye color. We have 2 alleles for any, one trait, one from our mother and one from our father. They may be the same form of the gene (homozygous) or two different forms (heterozygous). 4. Genes: are the smallest chemical parts that form segments of chromosomes. Genes determine what we look like. 5. Homozygous: a genotype consisting of two identical alleles of a gene for a particular trait. An individual may be homozygous dominant (AA) or homozygous recessive (aa). Individuals who are homozygous for a trait are also referred to as homozygotes. 6. Heterozygous: a genotype consisting of two different alleles of a gene for a particular trait. An individual that is heterozygous (Aa) is also referred to as hybrids. 7. Dominant: observed trait of an organism that mask the recessive allele of a trait 8. Recessive: trait of an organism that can be masked by the dominant form of a trait 9. Punnett Square: a simple graphical method of showing all of the potential combinations of offspring genotypes that can occur and their probability given the parent genotypes. Developed by Reginald Punnett in the early 1900 s while working with William Bateson. Both were instrumental in reintroducing Gregor Mendel s work. Mendel is considered the Father of Genetics, was a Catholic priest in the Augustinian order, and published his theories in Probability: the likelihood that a specific event will occur. Probability is usually expressed as the ratio of the number of actual occurrences to the number of possible occurrences. Genetics primer You have two copies of every gene. One of them came from your mom and one came from your dad. (They each also had two copies of each gene, but randomly gave one of each to you during your conception.) Using the example of brown eyes, if both copies of your brown eye gene say "Make brown eyes," then your eyes will be brown. On the other hand, if both copies say "Don't make brown eyes," then your eyes will be some other color (which other color depends on other genes). What happens if one copy says "Make brown eyes" and the other copy says "Don't make brown eyes"? You might think that you'd end up with something in between. But that's actually not what happens. What you end up with is just simply brown eyes. In fact, they will be just as brown as someone who has BOTH copies saying "Make brown eyes."

2 Biologists say that brown eyes are "dominant." You can think of it like this. The copy that says "Make brown eyes" is a really big, powerful gene. Whenever it gets into a cell, it overshadows anything else that's there and makes sure it gets expressed. On the other hand, the copy that says "Don't make brown eyes" is a little, quiet gene that allows the "Make brown eyes" gene to be expressed. The only time it gets heard at all is if there are two copies of it and no one else around to overshadow it. As a convention, the two copies of a gene are written using letters. Capital letters stand for dominant genes, so the "Make brown eyes" copy would be written B, and lower case letters stand for "recessive" (not dominant) genes, so the "Don't make brown eyes" copy would be written b. Since you have two copies, you get two letters. So an individual who got a B from mom and a B from dad would be written BB (homozygous dominant), someone who got a b from both parents would be written bb (homozygous recessive), and someone who got a B from one parent and a b from the other would be written Bb (heterozygous). Notice that BB and Bb individuals BOTH look exactly the same (they both have brown eyes), but their genes are different so their children might look different. Also, keep in mind that the only individuals who do not have brown eyes are bb individuals. Matching 1. Genotype a. the segment of DNA that determines a particular trait 2. Phenotype b. the form of the gene that shows up only when inherited 3. Allele from both parents 4. Heterozygous c. Two identical genes for the same trait 5. Homozygous d. an inherited trait which is present even when inherited 6. Dominant only from one parent. 7. Recessive e. one of the hereditary material for a particular trait 8. Punnett Square f. two different genes for the same trait 9. Probability g. a tool used to analyze possible breeding outcomes 10: Gene h. the likelihood of an occurrence i. the kinds of genes an individual carries j. the observable expression of a trait Sentence completion Complete the sentences using the following words: gene, trait, heredity, dominant, and recessive. 1. The segment of DNA that determines the inheritance of a particular trait is called a. 2. The passing of traits from parents to offspring is called. 3. An inherited characteristic of an organism is called a. 4. The gene shows up even when inherited only from one parent. 5. The gene shows up only when inherited from both parents.

3 Name Date Class Chapter 6 Test, continued INTERPRETING GRAPHICS Examine the diagram below and answer the questions that follow. Male parent Female parent White-fur alleles (bb) Black-fur alleles (BB) White-fur allele Black-fur allele White-fur allele Offspring Black-fur allele 15. When the cells in the male and female parent divide as illustrated, do they form body cells or sex cells? Explain. Copyright by Holt, Rinehart and Winston. All rights reserved. 16. Does the first-generation offspring have the mother s phenotype or the father s phenotype? 24 HOLT SCIENCE AND TECHNOLOGY

4 12 Section 12.2 Meiosis Study the Diagram Interphase Prophase I Metaphase I Anaphase I Telophase I Meiosis II Meiosis I Prophase II Metaphase II Anaphase II Telophase II Use the diagram to answer the questions. 1. Meiosis I begins with one cell. By the end of Meiosis II how many cells are formed? 2. Name a physical process that occurs more than once during meiosis. Answers will vary. 3. Cell division by meiosis is a way to produce gametes that have only half the number of chromosomes of the parent cell. Why is this important?

5 Name: Date: Period: Flower Structure and Reproduction Flowers are the plant's reproductive structures. Angiosperms are types of plants that bear fruits and flowers. Flowers are usually both male and female, and are brightly colored to attract insects to help them carry pollen used for sexual reproduction. Not all flowers are colorful, though. These flowers usually use the wind for pollination. Most flowers have certain structures in common that perform similar functions. Parts of the Flower The receptacle is the part of the branch on which a flower forms. Color the receptacle (B) brown. Sepals are leaf like structures that surround and protect the flower before it blooms. Color the sepals (C) green. Petals are the colorful part of the flower that attracts insects and even other small animals, such as mice, birds, and bats. Color the petals (D) a bright color of your choice. All flowering plants have flowers, but some are not brightly colored. The petals of these flowers are reduced or absent and the plant relies on the wind or water for pollination. The flower has both male and female reproductive parts. The female reproductive structures are called carpels. In most flowers, the carpels are fused together to form a pistil. Color the pistil (P) pink. The pistil has three parts, which can be seen, in the box labeled "pistil". The stigma at the top is often sticky and is where the pollen attaches. Color the stigma (J) purple. The style is the long tube that attaches the stigma to the ovary. Sperm from the pollen will create a pollen tube that will travel down the style to the ovules in the ovary. The ovules, or eggs, are stored in the ovary until they are fertilized. Plants can only fertilize eggs of the same species. Special chemicals prevent sperm from fertilizing the eggs of flowers that are not the same kind. Color the style (K) red, and the ovary (L) pink. Color the ovules (O) black. The male reproductive structures are called the stamens. Color the stamens (H) blue. Each stamen consists of an anther (A), which produces pollen, and a filament (F), which supports the anther. In the box labeled "stamen" color the anther dark blue, and the filament light blue. Pollen produced by the anther is carried by insects or other animals to the pistil of another flower where it may fertilize the eggs. The other flowers in the picture follow the same plan, although they come in many different colors and styles. Color each of the flowers according to the colors above (blue for stamen, pink for pistil, bright colors for the petals. etc.). Note that in some of the flowers, not all the structures are visible. Plant Reproduction Sexual reproduction in plants occurs when the pollen from an anther is transferred to the stigma. Plants can fertilize themselves: called self-fertilization. Self-fertilization occurs when the pollen from an anther fertilizes the eggs on the same flower. Cross-fertilization occurs when the pollen is transferred to the stigma of an entirely different plant. When the ovules are fertilized, they will develop into seeds. The petals of the flower fall off leaving only the ovary behind, which will develop into a fruit. There are many different kinds of fruits, including apples and oranges and peaches. A fruit is any structure that encloses and protects a seed, so fruits are also "helicopters" and acorns, and bean pods. When you eat a fruit, you are actually eating the ovary of the flower. 1. What is an angiosperm? 2. The flower attaches to what part of the plant? 3. Why are flowers brightly colored?

6 4. Name two animals that might pollinate a plant. 5. If the petals of a flower are reduced or absent, how is the plant pollinated? 6. The female reproductive structures are called the 7. Name the three parts of the pistil: 8. Where are the ovules stored? 9. Name the two parts of the stamen: 10. Describe sexual reproduction in plants. 11. The ovary develops into what structure? 12. Define fruit. 13. Some flowers are not brightly colored at all, but have a very pungent odor that smells like rotting meat. How do you think these flowers are pollinated? 14. In many flowers, the pistils and stamens reach maturity at different times. Considering what you know about pollination, why would this be an advantage to the plant?

7 Legend: Fill in the blank with the plant structure name and color the square the same color that was used for coloring the structure A: J: B : K: C: L: D: O: F: P: H:

8 Biochemistry Test Review I. Vocabulary: Know the definitions of the following: a. matter n. inorganic z. ionic bond b. atom o. organic aa. covalent bond c. element p. polar molecule bb. activation d. compound q. hydrogen bond energy e. proton r. dehydration cc. endothermic f. neutron synthesis reaction g. electron s. hydrolysis dd. exothermic h. atomic mass t. carbohydrates reaction i. atomic number u. monomer ee. reactants j. periodic table v. polymer ff. products k. ion w. protein gg. ph scale l. isotopes x. lipid hh. acid m. diatomic element y. nucleic acid ii. base II. Questions? 1. Draw an atom of Sodium using the Bohr model. 2. Describe the difference between polar and non-polar molecules. Give examples of each. 3. What do all organic molecules have in common? all inorganic?

9 4. Label the following diagrams as straight, branched, ring, saturated, and/or unsaturated. 5. What are some examples of a. monosacchrides? b. disacchrides? c. polysacchrides? 6. What are the monomers of: a. carbohydrates b. proteins c. lipids d. nucleic acids - 7. What are some of the functions of: a. carbohydrates? b. proteins? c. lipids? 8. What is a solution? solute? solvent? 9. Describe the ph scale and compare the differences in an acid and a base.

10 10. What are some properties of water that help give it the name universal solvent ; creates such a strong surface tension; cling to other materials such as creating a meniscus in a graduated cylinder? 11. In the McMush lab, describe the 4 tests were used to identify what organic compound was present? (Remember you tested 4 different compounds, so you need to identify those 4 compounds) 12. What is metabolism? 13. What is the role of an enzyme in a chemical reaction? 14. Create graphs showing how chemical reactions absorb and release energy. 15. Draw a graph of activation energy with and without an enzyme.

11 15. Identify these reactions as dehydration synthesis or hydrolysis and identify the basic macromolecules involved (carbohydrates, lipids, proteins, nucleic acids) What type of bond does the following diagram represent?

12 Fill in the? from the chart below. Elements Monomers Bond Type Example? C,H,O 1:2:1? Glycosidic?? Lipids C,H,O Glycerol and?? Ester Oils? Cholesterol C,H,O,?? Peptide Enzymes Insulin Hemoglobin Nucleic Acids C,H,O, N,? Nucleotides Phospho- Diester? RNA

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17 Principles of Ecology Ecology Study of interactions that take place between organisms and their environments Living things are affected by nonliving and living parts of the environment Abiotic factors: nonliving parts of the environment o Air, temperature, moisture, light, soil Biotic factors: living organisms in the environment o Producers: Organisms that take in energy from their surroundings to make their own food (Plants and some bacteria) o Consumers: Organisms that eat (consume) other organisms for energy (animals) o Decomposers: Consumers that eat waste products for energy. Waste products are feces, urine, fallen leaves, dead animals. (Fungi, some bacteria) 1 Ecology studies the relationship of organisms and their environment on several levels Organism Population: group of organisms, all of the same species, which interbreed and live in the same area at the same time o Organisms may compete with each other for resources such as food, water, space, mates, etc. Biological community: group of populations that live in the same area at the same time o A change in one population can cause a change in another population Ecosystem: a biological community and the nonliving things in the community s environment o Terrestrial ecosystem: located on land o Aquatic ecosystem: located in water

18 2 Biosphere: portion of the Earth that supports living things o Air, land, fresh water, salt water Habitat the place where an organism lives out its life Niche: all the strategies and adaptations a species uses in its environment o Includes all its interactions with the biotic and abiotic parts of the environment o Each type of organism occupies its own niche to avoid competition with other types of organisms Two species can share the same habitat but not the same niche o Example: Ants and bacteria both live in the dirt (habitat) but have different niches. Ants eat dead insects and bacteria eat dead leaves, dead logs, and animal waste. So ants and bacteria don t compete for resources. Survival Relationships Predator-prey: predators are consumers that hunt and eat other organisms called prey Symbiosis: relationship in which one species lives on, in, or near another species and affects its survival o There are 3 types of symbiosis 1. Mutualism: type of symbiosis in which both species benefit Ants living in the tropical acacia trees- trees are protected when ants attack animals that try to feed on the tree and ants receive nectar and shelter from the tree. 2. Commensalism: type of symbiosis in which one species benefits and the other species is neither harmed nor benefited Spanish moss grows on the branches of trees. The moss gets a habitat and the tree gets nothing. 3. Parasitism: type of symbiosis in which one species benefits and the other species is harmed Parasite: organism that harms but does not kill another organism Host: organism that is harmed by a parasite Ticks feed on dogs, people, etc. The ticks get food (blood) and the hosts lose blood and can be infected with disease.

19 3 Feeding Relationships Autotrophs: Organisms that make their own food (plants and some bacteria) Heterotrophs: Organisms that cannot make their own food and must eat other organisms o Herbivores: eat plants (cows) o Carnivores: eat meat (wolves) o Omnivores: eat plants and meat (humans)

20 Trophic Levels and Food Chains Trophic level: A feeding level in an ecosystem Food chain: lineup of organisms that shows who eats who o Shows how matter and energy move through an ecosystem 4 Eaten by 1 st trophic level: producers (make their own food) Eaten by 2 nd trophic level: primary consumer (eats plants) 3 rd trophic level: secondary consumer (eats meat) Eaten by 4 th trophic level: tertiary consumer (eats meat) Eaten by Bacteria Last trophic level: decomposer (eats dead animals)

21 Energy Pyramid Every time an organism eats, it obtains energy from its food So energy is transferred from the 1 st trophic level to the 2 nd trophic level to the 3 rd trophic level and so on. Some of this energy is lost along the way during an organism s metabolism and as heat This energy can be measured in kilocalories (kcal) Energy pyramid: picture showing how much energy is transferred to the different trophic levels in a food chain 5 Trophic Level Energy Available 4 th Tertiary consumers 10 kcal/m 2 /year 2 nd Primary consumers 1 st Producers 3 rd Secondary consumers 100 kcal/m 2 /year 1000 kcal/m 2 /year 10,000 kcal/m 2 /year

22 Food web A network of connected food chains More realistic than a food chain because most organisms feed on more than one species for food 6 Cycles in Nature There is only a limited amount of resources (water, oxygen, nitrogen, carbon) on the earth In order to keep these resources available to organisms, they must be recycled after they are used Cycle: a process that recycles a resource so that you end up with what you started with Nitrogen Cycle 1. Nitrogen fixation: Bacteria in the ground change nitrogen from the atmosphere (N 2 ) to different nitrogen

23 7 5. Denitrification: Bacteria change the nitrogen compounds back to N 2 and release it to the atmosphere 2. These bacteria live in plants and transfer the nitrogen compounds to the plants 4. Bacteria eat the dead animals and animal waste and take in the nitrogen compounds 3. Animals eat the plants and take in the nitrogen compounds Bacteria change nitrogen compounds back to nitrogen and release it into the atmosphere Bacteria eat dead animals Nitrogen in atmosphere Bacteria in roots change nitrogen to nitrogen compounds

24 2. Seepage: Water seeps into the ground and plants use it Water Cycle 3. Transpiration: Plants give off water to the atmosphere 8 1. Precipitation: Rain and snow fall from the atmosphere to the earth 2. Runoff: Extra water runs off the land to lower-lying bodies of water 3. Evaporation of water from the bodies of water back into the atmosphere

25 Oxygen-Carbon Cycle 9 1. Carbon dioxide (CO 2 ) and oxygen (O 2 ) are found in the atmosphere 2. Plants use CO 2 to make their own food (photosynthesis) 2. Animals and plants use the O 2 to make energy (respiration) 3. During photosynthesis, plants release O 2 back into the atmosphere 3. During respiration, animals and plants release CO 2 back into the atmosphere

26 Food Chains and Webs --- "What's for dinner?" Every organism needs to obtain energy in order to live. For example, plants get energy from the sun, some animals eat plants, and some animals eat other animals. A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. A food chain starts with the primary energy source, usually the sun or boiling-hot deep sea vents. The next link in the chain is an organism that makes its own food from the primary energy source -- an example is photosynthetic plants that make their own food from sunlight (using a process called photosynthesis) and chemosynthetic bacteria that make their food energy from chemicals in hydrothermal vents. These are called autotrophs or primary producers. Next come organisms that eat the autotrophs; these organisms are called herbivores or primary consumers -- an example is a rabbit that eats grass. The next link in the chain is animals that eat 1

27 herbivore - these are called secondary consumers -- an example is a snake that eats rabbits. In turn, these animals are eaten by larger predators -- an example is an owl that eats snakes. The tertiary consumers are eaten by quaternary consumers -- an example is a hawk that eats owls. Each food chain ends with a top predator and animal with no natural enemies (like an alligator, hawk, or polar bear). Food Chain Questions 1. What travels through a food chain or web? 2. What is the ultimate energy for all life on Earth? 3. Food chains start with what? 4. The 1 st organism in a food chain must always be what type of organism? 5. Name 2 food making processes. 6. Where do chemosynthetic bacteria get their energy? 7. Define herbivore. 8. Herbivores are also called. 9. What are animals called that feed on herbivores? 10. Secondary consumers are eaten by larger. 11. consumers eat secondary consumers. 12. Make a food chain with a producer and 3 consumers. 2

28 The arrows in a food chain show the flow of energy, from the sun or hydrothermal vent to a top predator. As the energy flows from organism to organism, energy is lost at each step. A network of many food chains is called a food web. Trophic Levels: The trophic level of an organism is the position it holds in a food chain. 1. Primary producers (organisms that make their own food from sunlight and/or chemical energy from deep sea vents) are the base of every food chain - these organisms are called autotrophs. 2. Primary consumers are animals that eat primary producers; they are also called herbivores (plant-eaters). 3. Secondary consumers eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals that eat both animals and plants). 4. Tertiary consumers eat secondary consumers. 5. Quaternary consumers eat tertiary consumers. 6. Food chains "end" with top predators, animals that have little or no natural enemies. When any organism dies, it is eventually eaten by detrivores (like vultures, worms and crabs) and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues. Some organisms' position in the food chain can vary as their diet differs. For example, when a bear eats berries, the bear is functioning as a primary consumer. When a bear eats a plant-eating rodent, the bear is functioning as a secondary consumer. When the bear eats salmon, the bear is functioning as a tertiary consumer (this is because salmon is a secondary consumer, since salmon eat herring that eat zooplankton that eat phytoplankton, that make their own 3

29 energy from sunlight). Think about how people's place in the food chain varies - often within a single meal! Food Web Questions 1. What is used to indicate the flow of energy in a food chain or web? 2. What happens to energy as we move from step to step in a chain or web? 3. Define food web. 4. What is meant by trophic levels? 5. Define autotroph. 6. The 1 st trophic level consists of consumers called. 7. Name the 2 nd trophic level (both names). 8. Secondary consumers may be eating meat or that eat both plants and animals. 9. What is the 3 rd trophic level called? 10. What is the 4 th trophic level called? 11. At the 5 th trophic level would be consumers that eat consumers. 12. Give an example of 3 detrivores. On what do they feed? 4

30 13. What organism feeds on dead plants and animals and helps recycle them? 14. Both and act as decomposers 15. Can an organism fill more than one trophic level --- yes or no? Give an example. Numbers of Organisms: In any food web, energy is lost each time one organism eats another. Because of this, there have to be many more plants than there are plant-eaters. There are more autotrophs than heterotrophs, and more plant-eaters than meat-eaters. Each level has about 10% less energy available to it because some of the energy is lost as heat at each level. Although there is intense competition between animals, there is also interdependence. When one species goes extinct, it can affect an entire chain of other species and have unpredictable consequences. 1. In food chains and webs, what trophic level must you have more of than others? 2. Each trophic level has how much LESS energy? 3. What may happen if a species goes extinct? Equilibrium As the number of carnivores in a community increases, they eat more and more of the herbivores, decreasing the herbivore population. It then becomes harder and harder for the carnivores to find herbivores to eat, and the population of carnivores decreases. In this way, the carnivores and herbivores stay in a relatively stable equilibrium, each limiting the other's population. A similar equilibrium exists between plants and plant-eaters. 5

31 Complete the Food Chains Worksheet Circle the organisms that complete the food chains below. 6

32 Food Chain Worksheet Read the passage then answer the questions below. 7

33 Food Web Worksheet Read the passage then answer the questions below. 8

34 Food Chain Quiz - Multiple choice comprehension questions Color the circle by each correct answer. 9

35 Food Chain Quiz #2 - Multiple choice comprehension questions Color the circle by each correct answer. 10

36 Match each Food Chain Word to its Definition. 11

37 Food Chain Trophic Levels - Worksheet 12

38 1 Have you ever seen a cat with a litter of baby kittens when all the kittens look different? Each kitten may have different hair colors, markings, or eye colors. Why? Each kitten received a different combination of genes from its parents. 2 Genes are segments of DNA that carry the instructions for the traits of an organism from parents to offspring. Genes are located on chromosomes in the nucleus of a cell. A chromosome is two very tightly coiled strands of DNA (deoxyribonucleic acid). 3 Each type of organism has a fixed number of chromosomes. Humans have 46 chromosomes in every cell of their bodies, except in the egg and sperm cells. Each egg and sperm cell has only 23 chromosomes. When an egg and a sperm cell combine during fertilization, they produce one cell with 46 chromosomes. 4 Whether that offspring will be a boy or a girl is determined by the chromosome given to it by the father. All egg cells have an X chromosome. All sperm cells have either an X or a Y chromosome. A female (the mother) can only give an X chromosome. A male (the father) can give either an X or a Y chromosome. If the father gives an X chromosome, the offspring will be a girl. If the father gives a Y chromosome, the offspring will be a boy. It's the Y that makes the guy. This is a good way to remember that males have a Y chromosome. 5 Each chromosome is divided into small sections called genes. Genes are the basic units of heredity. They carry codes that control the individual traits that the offspring inherit. Traits in humans such as eye color, height, skin color, face shape, shape of ear lobes, hairlines, and tongue rolling are all inherited traits. Except for identical twins, each person has a unique arrangement of genes. A chromosome may contain thousands of genes. Genes control traits. You inherited your genes and the traits they carry from your parents. You don't look exactly like either parent because you received only some genes from each parent. These genes combine in new ways during fertilization. Some genes control more than one trait, and some traits are controlled by more than one gene. 6 People inherit two genes for every characteristic, and they get one gene from each parent. Sometimes the two genes for one trait contain different codes. This affects how the trait appears in the child. For example, maybe both parents have brown eyes. Let's say that they each have one gene for brown eyes (B) and one gene for blue eyes (b). Brown eyes are dominant over blue eyes. That's why both the parents have brown eyes, even though they carry a gene for blue eyes. The gene for blue eyes is recessive. A person must have two genes for blue eyes for that person's eyes to be blue. There are four different ways these two parents can pass the gene for eye color to any children they might have. The father can give either a B or b gene. The mother can give either a B or a b gene. This results in four different combinations: Bb, bb, BB, or bb. The chance that a child born to these two parents will have brown eyes is 75%. Another way to say this is the probability is 3:1 that the child would have brown eyes. For the four combinations above, in every gene pair that has the gene for brown eyes, shown with a capital B, the child would have brown eyes. Two of those three children would also carry the gene for blue eyes and might pass blue eyes to their own children. But the child who has the BB combination will have only brown-eyed children. 7 Your genes determine your skin color, whether your hair is curly or straight, and whether or not you can roll your tongue into a U-shape. Each of these three traits is controlled by a gene. Humans have thousands of different genes. They are located on the 23 pairs of chromosomes in the nuclei of our body cells. One pair of chromosomes is different from all the others in your cells. This chromosome pair decides if you are male or female. Females have two X chromosomes (written XX). Males have one X and one Y chromosome (written XY). The X and Y chromosome pair is the only pair that doesn't match in size. The X chromosomes are larger than the Y chromosomes. 8 Sometimes genes controlling other traits are located on the X or Y chromosome. They are said to be a sex-linked trait. One example is the trait for red/green colorblindness. It is a recessive trait found only on the X chromosome, not the Y. Because males have only one X chromosome, they are more likely to have colorblindness than females. Another example of a sex-linked trait is the bleeding disorder

39 hemophilia. 9 Your genes are not exactly the same as that of your parents or your siblings. The only exception is if you have an identical twin. Identical twins are two individuals that formed from one egg fertilized by one sperm. Because identical twins form from the same egg and sperm, they have exactly the same genes. Identical twins are always either both boys or both girls. In science fiction, a clone is a person who has an exact copy of someone else's DNA. 10 Not all twins are identical. Sometimes a female releases two egg cells at the same time. Each egg can be fertilized by a different sperm cell and develop into a baby at the same time. This results in fraternal twins. Unlike identical twins, fraternal twins are no more genetically similar than any other two children from the same parents. Fraternal twins can be the same sex or different sexes. 1. Genes are. A Segments of DNA that carry the instructions for the traits of an organism from parents to offspring B Located on chromosomes in the nucleus of a cell C The basic units of heredity D All of the above 3. How many chromosomes are in the egg and sperm cells? A 46 B 23 C Why don't you look exactly like one of your parents? A Because you are not a clone B Because you got only some genes from each parent C Because genes combine in different ways during fertilization D All of the above 7. Identical twins can be different sexes. A False B True 2. How many chromosomes are in the skin cells of your body? A 88 B 46 C Girls have an XX chromosome. What do boys have? A BX B XY C XX 6. Why are more males colorblind than females? A Because colorblindness is a sex-linked trait B Because males' eyes are different from females' eyes C Because males can't see as well as females 8. All twins have exactly the same DNA. A False B True Name Date Period Genetics Practice Problems #1 1. For each genotype below, indicate whether it is heterozygous (He) or homozygous (Ho) AA Ee Ii Mm Pp Bb ff Jj nn LL Cc Gg kk oo HH

40 2. For each of the genotypes below determine what phenotypes would be possible. Purple flowers are dominant to white flowers Brown eyes are dominant to blue eyes PP BB Pp Bb pp bb Round seeds are dominant to wrinkled seeds RR Rr rr Bobtails in cats are recessive TT Tt tt 3. For each phenotype below, list the possible genotypes (remember to use the letter of the dominant trait) Straight hair is dominant to curly Straight Straight Curly Pointed heads are dominant to round heads Pointed Pointed Round 4. Set up the Punnett squares for each of the crosses listed below. Round seeds are dominant to wrinkled seeds. Rr x rr round? What percentage of the offspring will be RR x rr round? What percentage of the offspring will be RR x Rr round? What percentage of the offspring will be

41 Rr x Rr round? What percentage of the offspring will be Practice with Crosses. Show all work! 5. A TT (tall) plant is crossed with a tt (short plant). What percentage of the offspring will be tall? 6. A Tt plant is crossed with a Tt plant. What percentage of the offspring will be short? 7. A heterozygous round seeded plant (Rr) is crossed with a homozygous round seeded plant (RR). What percentage of the offspring will be homozygous (RR)? 8. A homozygous round seeded plant is crossed with a homozygous wrinkled seeded plant. What are the genotypes of the parents? x. What percentage of the offspring will also be homozygous? 9. In pea plants purple flowers are dominant to white flowers. If two white flowered plants are cross, what percentage of their offspring will be white flowered? 10. A white flowered plant is crossed with a plant that is heterozygous for the trait. What percentage of the offspring will have purple flowers? 11. Two plants, both heterozygous for the gene that controls flower color are crossed. What percentage of their offspring will have purple flowers? What percentage will have white flowers?

42 Name Date Period Genetics Practice Problems #2 - Writing Alleles Directions: Using the data in Table 1, write the genotype that corresponds to the phenotype descriptions Table 1: Mendel's Traits and Symbols for Pea Plants Traits Dominant Allele Symbol Recessive Allele Symbol Seed Shape Round R Wrinkled r Seed Color Yellow Y Green y Seed Coat Color Colored C White c Pod Shape Smooth S Constricted s Pod Color Green G Yellow g Stem Height Tall T Short t Flower Position Axial A Terminal a Phenotype Genotype Phenotype Genotype 1. Heterozygous for height 16. Constricted pod 2. Homozygous dominant for seed shape 17. Short height 3. Heterozygous colored seed coat 18. Green seed color 4. Homozygous green pod 19. Terminal flowers 5. Homozygous short 20. Pure wrinkled 6. Homozygous tall 21. Hybrid tall 7. Homozygous axial 22. Pure round 8. Homozygous terminal 23. Yellow seed pod 9. Heterozygous flower position 24. Hybrid smooth 10. Heterozygous seed color 25. Pure smooth pod 11. Homozygous smooth pod 26. Hybrid pod color 12. Homozygous constricted pod 27. White seed coat 13. Homozygous recessive for seed coat color 28. Wrinkled seed 14. Heterozygous for pod color 29. Pure colored seed coat

43 15. Homozygous round seed 30. Hybrid flower position Name Date Period Genetics Practice Problems #3 - Monohybrid Problems Worksheet 1 Directions: Using the table and rules below, complete Table 2: If you use a separate sheet of paper to set up and solve your problems, attach work showing Punnett Squares to receive credit. No Punnett squares No credit Rules for writing symbols 1. Dominant alleles are always capitalized usually by using the first letter of the trait as the symbol. 2. The recessive allele is always represented by the small case letter of the symbol for the dominant allele. EXAMPLE: homozygous recessive for stem length x heterozygous for stem height Genotypes Parents (P 1 ) tt x Tt Gametes (G 1 ) t,t (male) T,t (female) Phenotype Traits T = tall stem (dominant allele) t = short stem (recessive allele) F 1 By convention the dominant allele is written first t t F1 = Filial 1 = the probable offsprings of Parents (P1) Phenotypic Ratio = 2 Tall : 2 Short stems or 2 tall stem:2 short stem T Tt Tt Genotypic Ratio = 2 Tt : 2 tt...oor 1 Tt : 1 tt t tt tt Heterozygous for stem height : Homozygous recessive for stem height... Table 1: Mendel's Traits and Symbols for Pea Plants Traits Dominant Allele Symbol Recessive Allele Symbol Seed Shape Round R Wrinkled r Seed Color Yellow Y Green y Seed Coat Color Colored C White c Pod Shape Smooth S Constricted s Pod Color Green G Yellow g Stem Height Tall T Short t Flower Position Axial A Terminal a Problems 1. Heterozygous for seed color x Homozygous dominant for seed color (Example)

44 2. Heterozygous for flower position x Heterozygous for flower position 3. Homozygous recessive for seed shape x Heterozygous for seed shape 4. Homozygous dominant for stem height x Homozygous recessive for stem height 6. Heterozygous seed color x Homozygous recessive for seed color 7. Constricted pea pod x Constricted pea pod Table 2 Answers to monohybrid problems Parent Genotypes Male Gametes Female Gametes Phenotypic Ratio Genotypic Ratio

45 Genetics Practice Problems #4 Name: Period: 1. If a black heterozygous guinea pig is crossed with a homozygous white guinea pig with the genotype bb, what is the probability that the offspring will be white? 2. If two hybrid tall pea plants are crossed, what is the probability that the offspring will have the tall phenotype? 3. The different forms of a gene are called. 4. As a result of meiosis, the number of chromosomes a. is reduced by half in sex cells. b. stays the same in sex cells. 5. The purpose of mitosis is to a. make sex cells. b. make gametes. c. is doubled in sex cells. d. is quadrupled in sex cells. c. create identical cells. d. create different cells. 6. Both parents have genotype Rr. What genotype could the offspring have? 7. A true-breeding tall pea plant is crossed with a true breeding short pea plant all the offspring are tall. What is the most likely genotype of the offspring assuming a single gene trait? 8. If two white guinea pigs with genotype bb are crossed, what is the probability that the offspring will be white? 9. Which of the following statements about DNA is true? a. DNA is single-stranded. b. DNA has the sugar ribose. c. DNA contains uracil. d. DNA contains thymine.

46 10. One parent has genotype DD and the other has dd. All of the offspring will be. 11. In guinea pigs, the allele for short hair is dominant. What genotype would a heterozygous short haired guinea pig have? What genotype would a purebreeding short haired guinea pig have? What genotype would a long haired guinea pig have? Genetics Practice Problems #7 DIHYBRID CROSSES Name: Period: 1. In pepper plants, green (G) fruit color is dominant to red (g) and round (R) fruit shape is dominant to square (r) fruit shape. These two genes are located on different chromosomes. a. What gamete types will be produced by a heterozygous green, round plant? b. If two such heterozygous plants are crossed, what genotypes and phenotypes will be seen in the offspring and in what proportions? Gametes X Proportion Genotype Phenotype

47 2. About 70% of Americans perceive a bitter taste from the chemical phenylthiocarbamide (PTC). The ability to taste the chemical results from a dominant allele (T) and not being able to taste PTC is the result of having two recessive alleles (t). Albinism is also a single locus trait with normal pigment being dominant (A) and the lack of pigment being recessive (a). A normally pigmented woman who cannot taste PTC has a father who is an albino taster. She marries a homozygous, normally pigmented man who is a taster but who has a mother that does not taste PTC. a. What are the genotypes of the possible children? Hint: first determine the genotypes of the parents. Now that you have the genotypes of the parents, perform a Punnett square to determine what the F 1 offspring would be. Gametes X Possible genotypes b What percentage of the children will be albinos? c. What percentage of the children will be non-tasters of PTC? d. If this couple had ten children how many of the children will be non-tasters of PTC. 3. Wolves are sometimes observed to have black coats and blue eyes. Assume that these traits are controlled by single locus genes and are located on different chromosomes. Assume further that normal coat color (N) is dominant to black (n) and brown eyes (B) are dominant to blue (b). Suppose the alpha male and alpha female of a pack (these are the dominant individuals who do most of the breeding) are black with blue eyes and normal colored with brown eyes, respectively. The female is also heterozygous for both traits. What are the genotypes of the possible offspring? Possible genotypes

48 Gametes X What percent of the offspring will be normal colored with blue eyes? 4. In the breeding season, male Anole lizards court females by bobbing their heads up and down while displaying a colorful throat patch. Assume for this question that both males and females bob their heads and have throat patches. Assume also, that both traits are controlled by single locus genes on separate chromosomes. Now, suppose that anoles prefer to mate with lizards who bob their heads fast (F) and have red throat patches (R) and that these two alleles are dominant to their counterparts, slow bobbing and yellow throats. A male lizard heterozygous for head bobbing and homozygous dominant for the red throat patch mates with a female that is also heterozygous for head bobbing but is homozygous recessive for yellow throat patches. Possible genotypes Gametes X a. How many of the F 1 offspring have the preferred fast bobbing / red throat phenotype (assume 16 young)? (assume 100 young)? b. What percentage of the offspring will lack mates because they have both slow head bobbing and yellow throats? c. What percentage of the offspring will have trouble finding mates because they lack one of the dominant traits?

49 5. Carrion beetles lay their eggs in dead animals and then bury them in the ground until they hatch. Assume that the preference for fresh meat (F) is dominant to the preference for rotted meat and that the tendency to bury the meat shallow (S) is dominant to the tendency to bury the meat deep(s). Suppose a female carrion beetle homozygous dominant for both traits mates with a male homozygous recessive for both traits. What will be the genotype of the F 1 generation? What will be the phenotype of the F 1 generation? What will be the phenotypic ratio of the F2 generation if two of the F1 generation mated? Genotype Phenotype Gametes X What will be the genotypic ratio of the F 2 generation? FFSS : FFSs : FFss : FfSS : FfSs : Ffss : ffss : ffss : ffss What will be the phenotypic ratio of the F 2 generation? 6. Suppose in a strain of soybeans, high oil (H) content in the seeds is dominant to low oil content and four seeds (E) in a pod is dominant to two seeds in a pod. A farmer crosses two soybean plants, both with high oil content and four seeds per pod. The resulting F 1 offspring have a phenotypic ratio of 9:3:3:1 (High oil / four seeds : High oil / two seeds : Low oil / four seeds : Low oil / two seeds). a. What genotype were the parent plants?

50 b. Suppose the farmer chooses two of the high oil / four seed plants and crosses them. The F 2 generation have all high oil / four seed phenotypes. What were two of the several possible genotypes of the plants chosen by the farmer to cross? c. Which known genotypes might the farmer cross her high oil / four seed plants with to determine their genotype? PATTERNS OF INHERITANCE AND MEIOSIS Name: I. History Date: Period: A. Gregor Mendel 1865 Father of Genetics published a scientific paper of his research results (Darwin had a copy of Mendel's paper, but never opened it) 1. Investigated inheritance using pea plants. Recorded 7 traits, including color and shape of seeds, flower color, pod color and shape, height and position of flowers 2. Mendel discovered that traits could disappear in one generation, only to reappear in another generation, e.g. Parents (P1) with pure-breeding strains of red x white flowers => all red flowers (F1). Self-pollination of F1 => 3 red + 1 white (F2). This illustrates the disappearance of the color white flower in F1 generation and reappearance in F2 generation. After many more crosses Mendel suggested that there must be two heritable factors in each individual, and that these factors (alleles) segregate at random into gametes prior to mating. This conclusion is known as Mendel's first law: the Law of Segregation. 3. We can predict Mendel's monohybrid results if CC and Cc all produce colored red flowers while cc produces white flowers. Then CC (red) x cc (white) = Cc (red). We say that C and c are alternate alleles at the flower color locus. In this example, red flower color is dominant, i.e. the heterozygote genotype produces the same phenotype as one of the homozygote genotypes. If one phenotype is dominant, then the alternate phenotype is termed recessive. We see segregation of phenotypes in the F2 generation when two heterozygotes are mated together. 4. A simple way to predict the relative frequencies of each phenotype is to use a Punnett square, in which rows represent all possible alleles carried by eggs and columns represent all possible alleles carried by sperm. Then, each cell represents the genotype of the resulting zygote. Note, that if C and c are equally common in eggs and sperm, then there will be 3 red genotypes and 1 white genotype, or a 3:1 ratio.

51 5. Mendel also collected data on crosses between strains which differed in two traits. For example, he crossed a plant with round yellow seeds with a plant having wrinkled green seeds. The resulting F1 dihybrid cross produced approximately 9 round yellow, 3 round green, 3 wrinkled yellow and 1 wrinkled green plant (9:3:3:1 ratio). These ratios are predicted from a Punnett square in which each gamete carries an allele from two loci. One locus is for seed shape and the other is for seed color. R is dominant to r and causes round seeds while G is dominant to g and causes yellow seeds. The tendency for two traits to be inherited independently is known as Mendel s second law: the Law of Independent Assortment. II. Meiosis causes segregation and independent assortment A. Mitosis occurs by duplication of chromosomes, followed by one reduction division, thus one cell turns into two cells that are identical. B. Meiosis occurs by duplication of chromosomes, but is followed by two reduction divisions. Thus, one cell turns into four gametes that are not identical, but instead contain ½ the genetic material as the original cell. 1. Prophase I: homologous chromosomes condense, undergo duplication (forming sister chromatids) and crossing over, and centrioles move to the poles (opposite side of cell) 2. Metaphase I: microtubules connect from the centrioles to the centromeres, and the paired chromosomes line up along the equator of the cell 3. Anaphase I: paired homologous chromosomes separate and are pulled to alternate poles 4. Telophase I: chromosomes relax, nuclear membrane and nucleolus forms, centrioles move back together 5. Prophase II: chromosomes condense and centrioles move to the poles 6. Metaphase II: microtubules connect from the centrioles to the centromeres, and the paired chromatids line up along the equator of the cell 7. Anaphase II: paired sister chromatids separate and are pulled to alternate poles 8. Telophase II: chromosomes relax, nuclear membrane and nucleolus forms, centrioles move back together III. Consequences of meiosis A. Gamete formation. Note that meiosis in males (the sex with the smaller gamete) produces four functional gametes, while meiosis in females (the sex with the larger gamete) produces one functional gamete and three polar bodies, which disintegrate. This difference in gamete size is called anisogamy. Some plants are isogamous and do not produce polar bodies.

52 B. Meiosis also differs from mitosis because crossing over can occur during Prophase I. Crossing over is also known as recombination. Recombination together with independent assortment of chromosomes into gametes is responsible for Mendel s second law: the Law of Independent Assortment. C. Maintains variation: recombination + independent assortment of chromosomes 1. Due to chromosomal segregation -> produces 2^n types of gametes. With 23 pairs of chromosomes, each human produces 8 million gamete types without crossing over 2. This produces 70 trillion zygote combinations 3. And, each meiosis typically has 30 crossing-over events! IV. Linkage (exceptions to Mendel's second law) A. When genes are located near each other on a chromosomal, they do not assort independently. - Deduction from nonindependent assortment - Utility for gene mapping - Huntington's chorea. B. Sex linkage - Color blindness and hemophilia

53 Name Mrs. Chimento Living Environment GENETICS WORKSHEET 1. Label the pictures using the following words: DNA, RNA, bases, backbone, replication 2. The backbone is made up of A) nitrogen B) oxygen C) sugar and phosphate D) nitrogen and phosphate 3. What are the 4 bases in DNA?,, and How do the bases pair? with and with 4. Fill in the chart below # of strands Sugar (Deoxyribose or Ribose) Bases used DNA RNA 5. Label the parts of the diagram about protein synthesis: (Hint: DNA RNA) Word Bank DNA RNA Protein Translation Transcription Ribosome (Hint: RNA protein)

54 6. Label the pictures: cloning, gel electrophoresis, recombinant DNA 7. Fill in the Punnett Squares and answer the questions. Mother: blue eyes (bb) Father: brown eyes (Bb) Mother: tall (Tt) Father: tall (Tt) % of the offspring will have brown eyes % of the offspring will have blue eyes % of the offspring will be tall % of the offspring will be short 8. Define the following words: Replication: Mutation: Double Helix: 9. Proteins are made up of A) deoxyribose and phosphate B) amino acids C) nucleotides D) bases 10. DNA and RNA are made up of A) deoxyribose and phosphate B) amino acids C) nucleotides D) bases 11. Explain how you know the DNA came from 4 different people.

55 12. Fill in the blanks with the following words: a) The DNA is located in the. b) Proteins are made up of. c) carries an amino acid. d) make proteins. e) A is a change in DNA. f) cut DNA. g) The shape of DNA is called the. h) One thing that can cause mutations is. 13. Label the diagram below: trna radiation nucleus double helix amino acids restriction enzymes ribosomes mutation 2 1 Word Bank amino acid base mrna protein ribosome trna transcription translation

56 Key Concepts At the molecular level, both diffusion and osmosis are random processes that result in a net increase in entropy. (Entropy measures disorder in a system such as a group of molecules.) In a solution, diffusion results in a net redistribution of molecules from an area of higher concentration into an area of lower concentration. At dynamic equilibrium, the molecules will be equally distributed throughout the solution. Osmosis is the diffusion of water through a semipermeable membrane. Molecules that cannot diffuse directly across a cell membrane can cross the membrane with the aid of either channel proteins or transport proteins. Active transport requires energy, whereas passive transport does not. Vesicle-mediated transport, such as endocytosis and exocytosis, is another mode of transport and is active. Cells have receptors that receive extracellular signals. Cells have evolved intracellular pathways to respond appropriately to those signals. Lesson Objectives Identify two ways that molecules and ions cross the plasma membrane. Distinguish between diffusion and osmosis. Identify the role of ion channels in facilitated diffusion. Compare passive and active transport. Identify the connection between vesicles and active transport. Compare endocytosis and exocytosis. Outline the process of cell communication. Lesson Vocabulary Lesson 3.3 Vocabulary selectively permeable semipermeable passive transport diffusion concentration gradient equilibrium hypertonic hypotonic isotonic osmosis contractile vacuole facilitated diffusion transport protein channel protein gated channel protein carrier protein active transport sodium potassium pump endocytosis exocytosis phagocytosis homeostasis ligand G-protein linked receptor second messenger signal transduction pathway Check Your Understanding Recalling Prior Knowledge

57 Ask students what they already have learned about membranes. Ask: What characteristics do membranes have? How could these structural characteristics effect the functioning of membranes? These questions will serve as a bridge between Lesson 3.2 and Lesson 3.3. Give students about five minutes to write answers into the science notebooks. Ask for answers. Teaching Strategies Demonstration The following demonstration is designed to illustrate the concepts of osmosis and tonicity. Cut two slices of approximately the same shape and size from a potato. (Cut the slices so that they will easily fit into the bottom of a 250ml beaker.) Record their initial masses on a scale. Place one slice into a labeled 250ml beaker that contains 75ml distilled water. Place the other slice into a labeled 250ml beaker containing 75ml of a 15% sodium chloride solution. Let the potatoes sit for 20 minutes. During this time, ask the students questions such as those listed below: 1. What is osmosis? 2. What is a hypotonic solution? Isotonic? Hypertonic? 3. Which beaker contains the control for the experiment? 4. After in their respective solutions, do you think that the mass of either potato slice will change? If so, how? At the end of, remove the slices from the beakers. Blot very gently and briefly on the paper towel to remove external water. Record the masses of both slices. Discuss the actual and predicted results. [The potato slice incubated in 15% salt solution will lose water by osmosis and will weigh less at the end of 20 minutes] Using Visuals: Figure 9 Figure 9 shows exocytosis at a synaptic junction. Reviewing this figure with your students will reinforce their understanding of the concepts of vesicles, regulated secretion, ligands (remind students that the word ligand is one of the vocabulary words in this lesson), receptor proteins and cell-cell communication. Make photocopies of the figure for groups of 2-4 students. Ask the students to label as many of the structures in the figure as they can. When the groups are done, discuss as a class the function of nerve cells [cell-cell communication, specifically transmission of nervous impulses, refer to Nervous and Endocrine Systems chapter] and how specific molecules/structures of nerve cells (neurotransmitters and receptors) enable the nerve cells to accomplish their function.

58 Mode of exocytosis at a synaptic junction, where two nerve cells meet. Chemical signal molecules are released from nerve cell A by exocytosis, and move toward receptors in nerve cell B. Exocytosis is an important part in cell signaling. Differentiated Instruction: Compare/Contrast Table Instruct the students to make a table that compares and contrasts active transport and passive transport across biological membranes. For this activity, students can work in pairs. Teachers can pair SN, ELL, and LPR students with appropriate partners; one partner should write down the group s results in a table, and the other can present the results to the class. Choose several pairs of students to present their results to the class. ELL LPR SN A sample table is below: Type of Transport Passive Energy Required? No Active Yes Yes Enrichment: Research Protein Required? Sometimes; depends upon the size and charge of the molecule being transported. Result Movement of molecules down their concentration gradients. Movement of molecules up their concentration gradients. Many topics in cell biology come to life when students can relate them to personal experiences or to human health. The cell biology and medical aspects of cystic fibrosis

59 (mentioned in the Sodium-Potassium Pump section of Lesson 3) are quite interesting to students because they directly link a cell biology topic (chloride channels) to a human disease (cystic fibrosis). The website of the Cystic Fibrosis Foundation ( provides an appropriate and global introduction of cystic fibrosis to high school students. For this enrichment activity, students who need additional challenges can pick one of the bulleted questions (and its answer) to read, such as How does CF affect the lungs? They then can prepare and deliver a mini-oral presentation that addresses the question. In doing this project, students will get a jump ahead on the topics of Mendelian and Molecular Genetics, since cystic fibrosis is an autosomal recessive disease. Science Inquiry Asking a Question Teachers can do this activity as a demonstration or as part of a student laboratory lesson. The Question: Does dissolving a solute (sugar) have an effect on the final volume of a solute in which it is dissolved? Control: Place 80ml water in a 100 ml graduated cylinder. Record the volume. (80ml) Treatment A: Dissolve 5g sugar in 80ml water in a 250ml beaker. Use a stirring rod to speed up the process. When the sugar is dissolved, transfer the solution to a 100 ml graduated cylinder and record the volume. ml Treatment B: Dissolve 20g sugar in 80ml water in a 250ml beaker; use a stirring rod to speed up the process. When the sugar is dissolved, transfer the solution to a 100ml graduated cylinder and record the volume. ml The dissolved sugar will increase the volume to over 80ml in both the solutions; discuss with your class why this might be.

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