Bell Work 3/8/18 Mitosis: What occurs during mitosis? What are the products of mitosis? What is the purpose of mitosis?
Bell Work: 3/9/18 Complete the pre-assessment on your Anchor Activity Unit 6 sheet. Get out your notebooks for Meiosis notes.
REPRODUCTION: THE NATURAL PROCESS BY WHICH NEW ORGANISMS ARE GENERATED A Hydra budding Asexual Reproduction 1. Requires only 1 parent 2. Offspring are identical to parent 3. Examples: Binary Fission (bacteria), Budding (Hydra and yeast)
Sexual Reproduction 1. Requires 2 parents which each: provides a gamete sperm or egg Give DNA to offspring 2. Two gametes fuse to create a new organisms Fertilization 3. Offspring are different from both parents 4. Example: Meiosis
FERTILIZATION: Male & female reproductive cells (GAMETES) fuse to form a new cell (ZYGOTE) that develops into a new organism.
Gametes: Have 1 copy of each chromosome or gene Haploid, n Zygotes: Have 2 copies of each chromosome (1 from each parent) Diploid, 2n haploid diploid haploid
Somatic Cells: a. Have 2 copies of each gene diploid b. Make up most of the cells in your body
MEIOSIS Making the Reproductive Cells: Starts with Germ Cells
Interphase and Meiosis I 1. Interphase: DNA replication 2. Prophase I: Homologous chromosomes pair up Crossing over occurs
HOMOLOGOUS CHROMOSOMES A pair of chromosomes, one from each parent Carry the same genes Are identical in shape
Crossing Over: Homologous chromosomes exchange pieces Homologous Chromosomes Sister Chromatids Crossover
3. Metaphase I Homologous chromosomes line up at metaphase plate 4. Anaphase I Homologous chromosomes pulled to opposite ends of cell
5. Telophase I Nuclear envelope reforms 6. Cytokinesis 2 daughter cells with ½ number of chromosomes as parent. End of Meiosis I: 2 new cells each with 2 copies of 1 chromosome (from only 1 parent)
Meiosis II 1. Prophase II Nuclear envelope breaks down 2. Metaphase II Chromosomes line up at metaphase plate
3. Anaphase II Sister chromatids pulled to opposite ends of cell 4. Telophase II: Nuclear envelope reforms 5. Cytokinesis: 4 daughter cells with 1 copy of each chromosome
Meiosis DNA replication Diploid Cell 4 Haploid Cells each genetically different Meiosis I Meiosis II
DNA Replication Number of cell divisions MITOSIS Once in Interphase One MEIOSIS Once in Interphase Two Number of daughter cells and genetic composition 2, diploid, identical to parent 4, haploid, different from parent Role in the body Growth & Repair Reproduction
Bell Work 3/12/18 Make a Venn Diagram comparing Mitosis and Meiosis
Complete your Meiosis on the Table When you have completed your modeling of meiosis on the whiteboard your options are: 1. Complete the Meiosis worksheet due tomorrow 2. Take notes from the slides on the website (#21 to #26). 3. Do the Google Classroom Assignment (Chromosomes and Karyotypes) due Thursday 4. Work on Identifying Genetic Disorders with Karyotypes due Thursday
Bell Work 3/13/18 Make a Venn Diagram comparing Mitosis and Meiosis
Sources of Diversity in Meiosis & Sexual Reproduction 1. Crossing Over during Prophase I 2. Independent Assortment: Chromosomes are randomly segregated & sorted during metaphase I 3. Random Mating Combination of sperm & egg that form the zygote is random.
Mistakes during Meiosis Chromosome Mutations Breakage of a chromosome caused by errors in cell division or damaging agents such as radiation. Deletion of a part of a chromosome Duplication of a part of a chromosome Inversion of a chromosome Translocation between 2 different chromosomes
Nondisjunction: An error that can occur during meiosis in which chromosomes DO NOT separate.
Karyotypes: a photograph of chromosomes grouped as homologous pairs Can be used to determine gender and diagnose disease Human Fruit fly
Sex Chromosomes: All organisms have 1 pair, X and Y X and Y have different genes Females have 2 X chromosomes Males have 1 X & 1 Y
Autosomal Chromosomes: Paired 1 from each parent Each pair has the same genes
Bell Work 3/14/18 1. What is the gender of the individual shown on the right? 2. Is the Karyotype normal? If not, where is the abnormality?
XYY Syndrome: Male Taller Sexually normal Increased risk of learning disabilities
Turner Syndrome: Short Infertile Female
Down s Syndrome: Intellectual disability Weak muscle tone Increased risk of other medical conditions
Edwards Syndrome Low birth weight Heart defects Often die before birth or in 1 st month
Patau Syndrome Severe intellectual disabilities Physical abnormalities Small eyes Extra fingers or toes Many infants die in 1 st days
Klinefelter Syndrome: Male Produce less testosterone Delayed puberty Breast enlargement Sterile
Bell Work 3/14/18 1. What is the gender of the individual shown on the right? 2. Is the Karyotype normal? If not, where is the abnormality?
Triple X Syndrome: Female Often infertile Otherwise normal
Bell Work 3/15/18 What are 3 events that occur during meiosis and zygote formation that contribute to genetic diversity in a species? 1. Crossing Over during Prophase I 2. Independent Assortment: 3. Random Mating
Mendelian Genetics - Vocabulary Alleles: Different sequences of the same gene Alleles are either dominant or recessive Homozygous: both alleles in the organism are the same; Homozygous Dominant and Homozygous Recessive Heterozygous: each allele for a gene in the organism is different.
Genetics: Study of heredity Heredity: passing of traits from parent to offspring Genotype: the alleles an organism has for each gene Phenotype: the outward appearance of the genotype Trait: characteristic that varies from person to person, depends on combination of alleles for each gene Punnett squares: diagram showing the allele combinations that MIGHT result from the fusion of 2 gametes to form a zygote.
female / eggs Sample Cross: Rr x Rr R male / sperm R r R R R r R = violet, dominant r = white, recessive r R r r r Genotype Phenotype Genotype ratio Phenotype ratio RR = violet 1 Rr = violet 2 3 rr = white 1 1
Gregor Mendel (1822-1884) Austrian monk. Studied inheritance of traits in garden peas. 1866: Defined the laws that govern inheritance of traits.
Mendel s Pea Plant Experiments Pollen produced by the stamen, contains the sperm (male reproductive cell). Flower contains the ovary or egg (female reproductive cell).
Plants can be: a. Self-pollinated: pollen and ovary from same flower fertilize b. Cross-pollinated: pollen and ovary from different flowers fertilize
Generations in breeding: 1. P 1 : Parental generation. 2. F 1 : 1 st generation offspring (from breeding individuals in P1 generation). 3. F 2 : 2 nd generation offspring (from breeding individuals in F1 generation).
Mendel studied 7 traits in pea plants by: 1. Allowing plants to self-pollinate for many generations to create a pure strain (homozygous) 2. Cross-pollinating plants w/ different traits Observation: Offspring retain traits of parents. Conclusion: Physical traits are inherited as particles
Types of Genetic Crosses a. Monohybrid: Cross involving a single trait (for example flower color). b. Dihybrid: Cross involving 2 traits (for example flower color and plant height)
female / eggs P 1 Cross Monohybrid male / sperm Trait: Seed Shape Alleles: R Round; r Wrinkled Cross: Round seeds x Wrinkled seeds (RR x rr) Genotype: Phenotype: Genotype ratio: Phenotype ratio:
female / eggs F 1 Cross Monohybrid male / sperm Trait: Seed Shape Alleles: R Round r Wrinkled Cross: Round seeds x Round seeds (Rr x Rr) Genotype: Phenotype: Genotype ratio: Phenotype ratio:
Dihybrid cross P1 generation YR YR YR YR YYRR x yyrr yr yr yr yr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr YyRr F1 Generation yellow round green round yellow wrinkled green wrinkled
Dihybrid cross F1 generation YR Yr yr yr YyRr x YyRr YR Yr yr yr YYRR YYRr YyRR YyRr YYRr YYrr YyRr Yyrr YyRR YyRr yyrr yyrr YyRr Yyrr yyrr yyrr F2 Generation yellow round green round yellow wrinkled green wrinkled
Dihybrid Crosses true-breeding yellow, round peas F 1 generation self-pollinate F 2 generation cross-pollinate 9/16 yellow round peas YYRR Y = yellow R = round x YyRr yyrr yellow, round peas 3/16 green round peas y = green r = wrinkled 3/16 yellow wrinkled peas true-breeding green, wrinkled peas 1/16 green wrinkled peas 100% 9:3:3:1
Mendel s Laws of Inheritance: 1. Law of Dominance: Some alleles are dominant and some are recessive the dominant alleles mask the recessive alleles.
2. Law of Segregation: During gamete formation the 2 alleles that determine trait separate from each other and at fertilization are recombined.
3. Law of Independent Assortment: Alleles for different traits are sorted randomly during Metaphase I.
Each pair of alleles segregates into gametes independently Gametes with different combinations of alleles are produced in equal amounts YyRr Yr Yr yr yr YR YR yr yr
Bell Work 3/16/18 Trait: Seed Shape and plant height Alleles: R round r wrinkled T tall t - short Cross: 1 round seed, tall plant 1 wrinkled seed, tall plant (RrTt x rrtt) Phenotype Ratio:
Bell Work How do Mendel s observations of the pea plant offspring support the Law of Dominance? 3/19/18
Corn Snake Genetics Correction on the handout: Under Albino snake, change the genotype: It is NOT Bbrr it SHOULD be bbrr
Bell Work 3/20/18 To determine the true genotype of your new wild corn snake (B_R_), you cross it with an albino corn snake (bbrr). 1. What offspring phenotypes are possible for each possible genotype? 2. How will this tell you what the genotype of your snake is? br br br br BBRR BBRr BbRR BbRr
There are 2 types of chromosomes: Autosomes: Chromosomes with genes that do not determine gender. Sex Chromosomes: Chromosomes with genes that determine gender. Autosomal Traits: Genes carried on these chromosomes X-Linked Traits: Genes carried on the X Chromosome
Gene notation for X-linked traits: X upper-case letter : For the dominant allele on X-chromosome (X H ) X lower-case letter : For the recessive allele on X-chromosome (X h ) Y : For the male chromosome
Females have 2 X chromosomes: XX with allele shown by upper- or lower-case letter for each X. Heterozygous female: X R X r Males have 1 X which is paired with 1 Y chromosome: XY with allele shown by upper- or lower-case letter on the X. Male with recessive trait: X r Y Male with dominant trait: X R Y
In Fruit Fly, eye color is X-linked: Practice X r = white eyed (recessive) Cross white-eyed female fruit fly w/ red-eyed male fruit fly: White-eyed female genotype: Red-eyed male genotype: Offspring Ratios Gender: Genotype: Phenotype:
Hemophilia is an X-linked Trait: Practice Cross a female carrier of Hemophilia and a normal male 1. Normal (X H ) is dominant over hemophilia (X h ) 2. Parent Genotypes Mom: Dad: 3. Offspring ratios Gender: Genotype: Phenotype:
Background: Sickle cell Anemia is a recessive trait carried on chromosome 11. In regions where malaria is common, individuals who are heterozygous for sickle cell anemia have a 60% survival advantage compared to individuals who are homozygous dominant (AA). Individuals who are homozygous recessive for sickle cell anemia (SS) live on average to ~45 years. 3/22/18 Problem: Bell Work Two heterozygous parents living in Madagascar have children. What is the probability that they will have children who will survive to the age of 65 years?
Co-dominant Alleles: Both alleles contribute to the phenotype In some chickens neither black nor white feathers is dominant chickens with both alleles are checkered Alleles B and W BB = Black WW = white BW = Multi-colored W W B BW BW B BW BW
Multiple Alleles Genes with more than 2 alleles Blood Type has 3 alleles: I A, I B, i I A and I B : co-dominant i: recessive These alleles represent the antigens that are expressed on the surface of your red blood cells
Blood type Red Blood Cell antigen Plasma antibody Blood Type and Blood donors Antibodies in your plasma will attack only those red blood cells (RBCs) with an antigen different to the one on your own RBCs.
Genotypes I A I A I A i I B I B I B i I A I B i i Phenotype A A B B AB O RBC * Antigen A A B B A & B none Plasma Antibody B B A A None A & B
Malaria and the Inheritance of Sickle Cell Anemia Sickle Cell is an example of a co-dominant trait: Individuals w/out the disease have 2 normal alleles AA Individuals w/ 1 diseased allele have the trait AS Individuals w/ 2 diseased alleles have the disease SS
The Ghost in Your Genes
Bell Work: 4/2/18 About 70% of Canadians get a bitter taste from the chemical phenyl thiocarbamide (PTC), while the other 30% do not. The ability to taste PTC (T) is a dominant characteristic, while taste-blindness to it is recessive (t). Tongue-rolling is dominant (R); inability to roll the tongue is recessive (r). A tongue-rolling woman who is taste-blind for PTC has a father who could not roll his tongue but could taste the PTC chemical. She marries a man who can taste PTC but cannot roll his tongue. His mother was taste-blind to the chemical. Show the possible children this couple could produce. Use a Punnett square to illustrate your answer. Daughter Genotypes: Her Fathers Genotypes: Husband Genotypes: His Mothers Genotypes:
A tongue-rolling woman who is taste-blind for PTC has a father who could not roll his tongue but could taste the PTC chemical. She marries a man who can taste PTC but cannot roll his tongue. His mother was taste-blind to the chemical. Show the possible children this couple could produce. Use a Punnett square to illustrate your answer. Daughter Genotypes: Her Fathers Genotypes: Husband Genotypes: His Mothers Genotypes: Offspring Genotype Ratio: Offspring Phenotype Ratio:
Incomplete dominance: One allele is not completely dominant over another Some flowers show incomplete dominance in flower color: Alleles R and W RR = red WW = white RW = pink
Polygenic Inheritance: The inheritance pattern is controlled by two or more genes each with two alleles. Polygenic inheritance shows up as a range of variation such has height, skin color or hair color. The results of an average population will yield a bell-shaped curve.
Height is an example of an incompletely dominant trait that is determined by more than one gene.
Example of inheritance of height: keeping it simple, we will only consider only 2 genes (T & H). TTHH: very tall TtHh: med. TtHH or TTHh: tall TtHh, tthh, TThh: med. tthh: short What is the probability that 2 medium height parents will have tall or very tall children?
Eye Color in Humans: Polygenic Trait At present, three gene pairs controlling human eye color are known. Two of the gene pairs occur on chromosome pair 15 and one occurs on chromosome pair 19. One gene, on chromosome 15, has a brown and a blue allele. The second gene, located on chromosome 19, has a blue and a green allele. The third gene, located on chromosome 15, is a central brown eye color gene.
1. What is happening in diagram A? 2. What phases of meiosis does diagram A represent? A Bell Work 4/3/18 3. What is happening in diagram B? 4. What phases of meiosis does diagram B represent? B
Metaphase I Anaphase I Metaphase II Anaphase II
Bell Work 4/4/18 & 4/5/18 Essential Question Notecard: What is the role of meiosis in sexual reproduction and genetic variation? Possible vocabulary: Crossing over, Random mating, Haploid, Diploid, Gametes, Independent assortment
Bell Work 4/5/18 & 4/6/18 Essential Question Notecard: How can the ratio of offspring be predicted from patterns of inheritance? Possible vocabulary: Allele, co-dominance, Punnett Square, gametes, trait, dominance, recessive, genotype, incomplete dominance, phenotype
Bell Work 4/6/18 & 4/9/18 Essential Question Notecard: How does the environment influence the expression of genetic traits?
Pedigree Charts Show how a trait is passed from one generation to the next. Can be used to Infer the genotypes of family members Study the inheritance of genetic disorders
Parts of a Pedigree Squares: males Circles: females Horizontal lines: breeding couples Vertical lines: connect parents to children Shading: individuals with the trait being studied
Half shading or a dot: carriers of the trait No shading: individuals without the trait being studied Diagonal line: death Roman numerals: generations Numbers: identify individuals in a generation
Interpreting Pedigrees 1. Is the trait dominant or recessive? Trait skips a generation? Most likely Recessive Trait occurs every generation? Most likely Dominant
2. Is the trait autosomal or sex linked? Affects males & females equally? Autosomal (i.e. Aa) Affects one sex more than the other (i.e. mostly males)? Sexlinked (X A X a, X a Y)
Pedigree Chart for Eye Color (autosomal) What are genotypes of individuals 8 & 9?
Huntington s Disease Autosomal Dominant (H, h) What is genotype of individuals 1, 2, 3, & 4? 3 1 2 4
Hemophilia: X-linked recessive trait (X h ) What are the genotypes of the following individuals: 1: 5: 7: 8: Individuals with hemophilia are shaded
Bell Work 4/9/18 The pedigree chart shows the blood types of three generations of family members. Some of the phenotypes are shown. 1. What is the genotype of individuals 1-6? 2. Give the probable genotype of all other family members.
Building a Pedigree Chart: The father, Tom, & mother, Diane, have 3 children. The 2 oldest children are Anna and Mary and the youngest is Teddy. The oldest, Anna, is married & has an older son, Will, and a younger daughter, Vanessa. Mary is also married and has a son, Patrick. Teddy is not yet married. Everyone in this family is right-handed except the father, the oldest daughter, and the granddaughter. Right-handedness is dominant.
Cystic Fibrosis: What is the pattern of inheritance? What are the Genotypes of the individuals?
Hypercholesterolemia (H, h) Autosomal or X-linked trait? Dominant or Recessive? What are the Genotypes of the individuals?