GENETICS REVIEW QUESTIONS WITH ANSWERS

1. The passing on of traits from parent to offspring is called…… ?? 2. The gamete that contains genes contributed by the father is called…. ?? 3. The gamete that contains genes contributed by the father is called…. ??

4. Define heterozygous. How about a synonym for this term. 5. Define homozygous. 6. Create a genotype for homozygous recessive. 7. Create a genotype for homozygous dominant.

8. Create a genotype for heterozygous 9. What is an allele? 10. What is a zygote?

ANSWERS 1.Heredity2. sperm3. egg 4. An organism carrying 2 different alleles of the gene in question. “Hybrid” is a synonym. 5. An organism carrying 2 copies of the same allele of the gene in question.

6. aa7. AA8. Aa 9. One of several alternate forms of a particular gene 10. A fertilized egg (the first cell of life)

11. The two alleles of a given gene separate from each other during gamete formation. Occurs because of the separation of homologous chromosomes during meiosis. What is the name of this Law? 12. The distribution of alleles for one trait into the gametes does not affect the distribution of alleles for other traits. Occurs with genes that are located on different chromosomes. What is this the name of this Law? 13. Some alleles are dominant and others are recessive. What is the name of this Principle?

ANSWERS 11. Law of Segregation 12. Law of Independent Assortment 13. Principle of Dominance

14. What type of inheritance involves a red flowering plant crossed with a white flowering plant producing a pink flowering plant? 15. What type of inheritance involves a black chicken with a white chicken producing a black and white-speckled chicken? 16. If the above occurs with two similarly colored cows mating what is the black and white offspring called?

ANSWERS 14. Incomplete dominance 15. Codominance 16. Roan calf

17. Many genes have more than 2 alleles, such as the color of a Labrador Retriever (black, golden and chocolate). What is this called? 18. What are the three blood type alleles? 19. The type of inheritance controlled by more than 2 genes, like skin, eye and hair color is called… ?

ANSWERS 17. multiple alleles 18. A, B and O 19. polygenetic inheritance

20. If you were going to perform a test cross for a black rat (the dominant phenotype), what type of rat would you cross it with? 21. In an organism with a genotype of AaBBCc, what are the possible gametes?

22. The chart that traces the inheritance of hemophilia in the royal family is called….? 23.In this chart, how are females represented? 24. In this chart, how would you indicate a male that has the disorder? 25. In this chart, what are two ways of showing that an individual is a carrier?

ANSWERS 20. a recessive white rat 21. ABC, ABc, aBC, aBc 22. Pedigree23. circles 24. Filled in (blackened) square 25. Half shaded or a dot inside the shape.

NAME THE AUTOSOMAL RECESSIVE DISORDER 26. Excessive mucus in lungs, digestive tract and liver; increased susceptibility to infections. 27. Accumulation of the amino acid phenylalanine in tissues; lack of normal skin pigment; symptoms can be lessened with good diet 28. Lipid accumulation in brain cells; mental deficiency; blindness; death in early childhood

ANSWERS 26. cystic fibrosis 27. PKU (phenylketonuria) 28. Tay-Sachs disease

29. Name two disorders caused by dominant alleles 30. Why is sickle cell disease considered codominant? 31. What is the advantage of being a carrier for the sickle cell allele?

ANSWERS 29. Huntington’s disease 30. There are two alleles and each is expressed in the phenotype of heterozygous individuals (or carriers) 31. Resistance to malaria

QUESTIONS ABOUT MEIOSIS 32. What is meiosis? 33. Describe the main result of meiosis. 34. What is the difference between mitosis and meiosis? 35. What do “diploid” and “haploid” mean?

36. What is “crossing over?” 37. In human cells, 2N=46. How many chromosomes would you expect to find in a sperm cell? An egg cell? A white blood cell?

ANSWERS 32. Process by which the number of chromosomes in a cell are cut in half through the separation of homologous chromosomes in a diploid cell 33. Four haploid cells genetically different from each other and from the original cell. 34. Mitosis produces 2 genetically identical diploid cells; meiosis produces 4 genetically different haploid cells.

35. Diploid means two sets of chromosomes; haploid means one set of chromosomes. 36. Homologous chromosomes pair up and form tetrads, which may exchange portions of their chromatids, resulting in the exchange of alleles between homologous chromosomes. 37. Both sperm and egg (the gametes) have 23 chromosomes (because they are haploid cells). A white blood cell has 46 chromosomes (23 pairs) because it is a diploid cell.

38. Name 3 disorders that are sex-linked 39. Is a boy or girl most likely to inherit a sex-linked disorder? Why? 40. Do a punnet square and show how a girl can inherit color blindness.

ANSWERS 38. Color blindness, Hemophilia and Duchenne Muscular Dystrophy 39. A boy. Since sex-linked disorders are passed on by the mother, and a boy just gets one X chromosome, there is a chance he will get the disorder if his mother is a carrier. 40. The father must have color blindness and the mother must either have it or be a carrier.

Blood

What are Blood Types? Differences in human blood due to presence or absence of carbohydrate molecules called antigens and antibodies on the cell’s surface. Antigens located on surface of RBC and antibodies are in blood plasma. A and B are co-dominant. O blood is recessive to A and B. Positive Blood is dominant to Negative. Individuals have different types and combinations of these molecules which are inherited One allele from mother and one from the father Located on Chromosome 9

ABO blood groups AB0 blood grouping system According to the AB0 blood typing system there are four different kinds of blood types: A, B, AB or 0 (null). Blood group A A antigens and anti-B antibodies Blood group B B antigens and anti-A antibodies Blood group AB Both A and B antigens, neither anti-A nor anti-B antibodies Blood group 0 Neither A nor B antigens, both anti-A and anti-B antibodies

Type AB blood has both A and B antigens. Antigens are surface proteins on the red blood cell. Type AB blood lacks both anti-A and anti-B antibodies. Antibodies recognize and attack another blood type. Since there are no antibodies, a person with AB blood can accept any type of donated blood. People with type AB blood are “universal recipients.”

Type O blood lacks both A and B antigens Type O blood has both anti-A and anti-B antibodies. Since no antigen is on its surface, it will react and ‘freak out’ when other types of blood are introduced. People with Type O blood are “universal donors.” They can only receive Type O blood.

Rh Factor If people have the antigen they are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems. – 85% of all people are Rh+ – 15% of all people are Rh-