2.3 - Genetics, Technology, Society, and the Environment Accidental Changes to DNA:

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1 2.3 - Genetics, Technology, Society, and the Environment Accidental Changes to DNA: Two main cases: 1 The damaged DNA is detected by the cell and the damage is repaired or the cell is destroyed. 2 The damage is not detected and normal cell function can be disrupted and diseases, such as cancer, can result. Unit 1 - Life Science 1 / 14

2 Genetic Conditions: Besides cancer, there are many other genetic conditions that can result from damaged DNA. A genetic condition is a disease or disorder that is caused by damaged or faulty DNA. Genetic conditions are caused by recessive alleles. Therefore, to inherit the condition, offspring must inherit a recessive allele from each parent. = such conditions are rare. Unit 1 - Life Science 2 / 14

3 Sex-linked Genetic Conditions: Like all chromosomes, sex chromosomes exist in pairs. In humans, they are the X and Y chromosomes. Males have one X and one Y chromosome. Females have two X chromosomes. Unit 1 - Life Science 3 / 14

4 Most traits are linked to the X chromosome, but some are on Y. Genes that are located only on the X or the Y chromosome are said to be sex-linked genes. Males are more likely to inherit sex-linked genetic disorders because they receive only one X chromosome. If it is affected with a recessive allele, he will automatically display the recessive trait. Unit 1 - Life Science 4 / 14

5 Examples of sex-linked genetic conditions: Colour Blindness - Red-green colour blindness is common. The allele for red-green colour blindness is recessive and the gene that enables us to distinguish red and green is found on the X chromosome. Hemophilia - is linked to the X chromosome. Hemophilia is a disorder in which blood is unable to clot. A red-green colour blind test. Can you see the word imbedded in the picture? Unit 1 - Life Science 5 / 14

6 Other Genetic Conditions: Not all genetic conditions are the result of recessive alleles or sex chromosomes. Example: Trisomy 21 (formerly called Down Syndrome) is a condition caused by a different number of chromosomes (47). Unit 1 - Life Science 6 / 14

7 Video & Exit Slip Exit Slip: Watch: Sex-linked Genetics URL: 1 Genetic conditions are caused by: dominant alleles, recessive alleles, cancer, or the environment? 2 The condition in which blood is unable to clot is called what? 3 Which group below are more likely to inherit sex-linked genetic disorders? Females Males Unit 1 - Life Science 7 / 14

8 Quiz Review Asexual or Sexual Reproduction? 1 Genetic information from two cells is combined to produce a new genetically unique organism. 2 Reproduction that involves only one parent. All offspring are genetically identical to that parent. 3 Can produce lots of identical individuals very quickly. 4 Offspring show variation, which helps species survive changes in its environment. Unit 1 - Life Science 8 / 14

9 Types of Asexual Reproduction 1 Occurs when single-celled organisms divide into two identical daughter cell that are clones of the parent cell. 2 The parent produces a small bud, or a miniaturized clone that eventually detach and become separate individuals. 3 The process by which unfertilized, haploid eggs mature into new organisms. 4 Is described as reproduction of offspring by plants that does not involve the formation of seeds. Unit 1 - Life Science 9 / 14

10 Sexual Reproduction in Humans - Terms 1 Specialized sex cells are called. 2 Sex cells from females are called and sex cells from males are called. 3 The union of sperm and egg is called. 4 The is the first cell of life. Once it divides and becomes multicellular it is called an. 5 What is meiosis and how is it different from mitosis? Unit 1 - Life Science 10 / 14

11 Sexual Reproduction in Plants - Terms 1 In plants, the reproductive organs are called. 2 contains male gametes. 3 contain the female gametes. 4 is when pollen is transferred from the anther of the stamen to the stigma of the pistil. 5 is when the pollen of one plant is carried to the stigma of another by wind, water, or animals (bees, butterflies, etc.). Unit 1 - Life Science 11 / 14

12 2.1 - Variation, Characteristics, and Traits 1 is a distinguishing quality or feature such as eye colour. 2 Brown eyes and blue eyes are variations of eye colour. These are examples of. 3 Attached versus unattached earlobes is an example of variation. Unit 1 - Life Science 12 / 14

13 2.2 - Heredity and Genetics 1 Name the four chemicals that make up DNA. Pair them up accordingly. 2 A is an uninterrupted segment of DNA. 3 DNA is packaged in, which are like volumes in a set of encyclopedias. 4 What is an allele? Unit 1 - Life Science 13 / 14

14 Punnett Squares Question: A brown-eyed man marries a blue-eyed woman and they have three children, two of whom are brown-eyed and one of whom is blue-eyed. Draw a Punnett square to determine the different eye colour probabilities of their offspring. Unit 1 - Life Science 14 / 14