Genetics Study Guide

1. Genetics Study Guide

2. 1. What is a male sex cell called? 2. What is a female sex cell called? Sperm Egg 3. There are 23 chromosomes in each of the above. 4. Another term for sex cell is called germ cell.

3. 5. When do eggs begin to mature in a female? 6. Where does fertilization of an egg take place? Puberty Fertilization takes place in the oviducts.

4. 7. What is a zygote and what does it contain? A zygote contains a sperm and egg and equal amounts of DNA from each parent, 23 chromosomes from mom and 23 chromosomes from dad.

5. 8. Make sure you know the location of the structures in the male and female reproductive systems. (Know diagrams) A- Testes B- Vas Deferens C- Bladder D- Penis E -Urethra F- Prostate F E Diagrams

6. Female Reproductive System A- Oviduct B- Ovary C- Vagina D- Uterus E- Cervix F- Eggs F E

7. 9. Know the various parts (structure) and function of each of the cell organelles. Describe their functions. cell wall- found only in plant cell, gives support to cell cell membrane- protects the cell and controls what goes in and out of cell nucleus- control center of the cell chromatin- contain genetic material and make up chromosomes. mitochondria- the powerhouse of the cell endoplasmic reticulum- passageways for materials ribosomes- produce proteins lysosomes- clean up the cell golgi bodies- mail room of the cell; receive and send materials to all parts of cell vacuoles- storage sacs in cell chloroplasts- make food for plant cells using sunlight

8. Plant Cell

9. Animal Cell

10. 10. Define mitosis and meiosis. Mitosis is the second stage of the cell cycle. (PMAT) Somatic cells undergo mitosis. Meiosis is the process by which the number of chromosomes is reduced by half to form sex cells (sperm and egg). So one cell will undergo meiosis and produce four cells. If a cell has forty chromosomes then after meiosis how many will each cell have? 20

11. 11. Compare and contrast mitosis and meiosis. Include four difference and four similarities. Mitosis occurs in body (somatic) cells while meiosis occurs in germ (sex) cells. Mitosis produces two cells while meiosis produces four. Mitosis produces the same number of chromosomes in the resulting cell while meiosis produces half of the original number. Mitosis produces identical cells while meiosis produces unique cells. This gives way to genetic variation. They both occur in all living things. Both begin with one cell. In order for both mitosis and meiosis to occur, the cell must have equal amounts of chromosomes from both parents. It is essential for all living things to undergo both mitosis and meiosis because as cells die, new ones are made.  

12. 12. Be able to identify the stages of Interphase, PMAT and cytokinesis. Interphase- cell makes a copy of its DNA and centrioles are copied PMAT- The stages of mitosis when the cell’s nucleus divides into new nuclei. Cytokinesis- The cell membrane pinches in around the middle of the cell and it splits into two.

13. 13. Draw a cell (nucleus has four chromosomes) undergoing Prophase, Metaphase, Anaphase and Telophase. A- Interphase B- Prophase C- Metaphase D- Anaphase E- Telophase F- Cytokinesis

14. 14. The structure of DNA contains what three major features? nitrogen bases, sugars (deoxyribose) and phosphates. The sugar and phosphates make up the sides of the ladder while the nitrogen bases make up the rungs.

15. DNA Molecule

17. 15. a. What are nitrogen base pairs? b. What would be the matching base pairs to the following strand? A-G-G-T-C-A-A-C-T They are molecules that contain the element nitrogen and they are adenine, cytosine, guanine and thymine. They are the rungs of the dna ladder. T-C-C-A-G-T-T-G-A

18. 17. Define heredity, genetics and trait. NO #16 Heredity- passing of physical characteristics from parents to offspring Genetics- the scientific study of heredity Traits- a different form of a characteristic

19. 18. Provide an example of an allele using the letter T. T or t- single alleles TT, Tt, tt- combination of alleles

20. 19. How is a dominant allele different from a recessive allele? A dominant allele always shows up in the organism when the allele is present. A recessive allele is hidden when the dominant allele is present.

21. 20. Differentiate between homozygous and heterozygous. Heterozygous describes two different alleles for a trait (Dd) and homozygous describes an organism that has two identical alleles for a trait (DD or dd)

22. 21. Differentiate between purebred and hybrid. Purebred is a homozygous individual while a hybrid is a heterozygous individual.

23. 22. What is an example of a genotype? A phenotype? A genotype would be the genetic makeup or allele combination such as AA. A phenotype would be the organism’s physical makeup, or visible traits such as blond hair. Remember: PHysical= PHenotype

24. 23. What is the difference between a chromosome and a gene? Chromosomes are made up of many genes joined together. Each gene controls a trait. You have twenty three pairs of chromosomes yet each cell contains tens of thousands of genes.

25. 24. Provide an example of a gene that is controlled by two alleles. Widow’s peak vs. straight hairline, cleft chin vs. normal chin

26. 25. Provide an example of a gene that is controlled with multiple alleles. Blood type, eye color

27. 26. Provide an example of a gene that is controlled by many genes. Skin color, height

28. 27. Why are sex-linked disorders more common in males than females? Since males only have one X chromosome, they will not be able to mask the normal allele like females can with their second X. In females, a dominant allele on one X will mask a recessive on the other X. Males only have one X, so that is not a possible scenario.

29. 28. True or False. The sex chromosomes only carry genes that determine whether a person is male or female. False. The X chromosome carries many genes such as certain sex related disorders. Males are more likely to acquire these diseases because they only have one X chromosome while females have two X’s so the dominant X (normal) can mask the recessive X (disease). Males cannot ever be carriers while females can.

30. 29. What are some examples of sex-linked disorders? Hemophilia Colorblindness

31. 30. Create a Punnett square of a man who has colorblindness with a woman who is normal. What is the outcome that their sons will be colorblind? Their daughters? XE XE Xe Y None of their sons will be colorblind. Their daughters will both be carriers but will not be colorblind.

32. 31. If each of their sons marry a woman who is a carrier for colorblindness, what are the chances that their kids will have the disorder? XE Xe XE Y There is a 25% chance that their child will have the disorder and a 50% chance among the males.

33. 32. If Maggie has a widow’s peak marries Jason who doesn’t have one, what are the chances that their kids will have widow’s peaks? List the phenotypic and genotypic ratios. W W Genotype- 100% Ww Phenotype- 100% widow’s peak w w

34. 33. Make sure you know how to draw a pedigree. Use 30 and 31 to create a pedigree. Normal woman marries colorblind man, two female carries, two normal males Sons marry carriers and have normal son, normal daughter and carrier daughter and colorblind son