LECTURE 4 - STUDY GUIDE

Question 1

Is sex determination the same in all organism? (know the answer and anything else we discussed regarding this question)

Answer 1

Not all organisms have same number of chromosomes among mother and father so not really universal

Question 2

54. Usually only ______________ (number) is activated in each female mammal. Fill in the blank.

Answer 2

one X chromosome

Question 3

55. The inactivated X chromosome of a female is highly condensed making it visible as an intensely straining ______________ attached to the nuclear membrane. Fill in the blank.

Answer 3

Barr bodies

Question 4

56. Females that are heterozygous for X chromosome alleles are ______________. Their individual cells may express different alleles, depending on which chromosome is inactivated. Fill in the blank.

Answer 4

Genetic mosaics

Question 5

57. Regarding synapsis of chromosomes, genetic recombination occurs less often between certain genes. Why?

Answer 5

if two genes are too close together, crossing over will not occur, synapsis can occur, but crossing over can’t occur

Question 6

58. As distance between two genes on a chromosome ___________, the probability of recombination between them increases. Fill in the blank.

Answer 6

decreases

Question 7

59. Regarding changes in chromosomes, what is disjunction?

Answer 7

when homologous or sister chromatids separate properly during meiosis

Question 8

60. What is the definition of (a) aneuploidy, (b) monosomy, or (c) trisomy?

Answer 8

Aneuploidy - losing or gaining required number

Monosomy - One less chromosome

Trisomy - more chromosomes

Question 9

61. Which statement describes an example discussed in class regarding X chromosomal genetic defects?

Answer 9

Turner’s Syndrome (X)

Question 10

62. Which statement describes an example discussed in class regarding Y chromosomal genetic defects?

Answer 10

Jacob’s Syndrome

Question 11

63. Which statement accurately describes how someone would receive either (a) sickle-cell disease, (b) hemophilia, or (c) Huntington’s disease?

Answer 11

Sickle cell disease

• only way for them to pass it on is if they are carriers and recessive themselves

Hemophilia

• Females need both recessive (can only be carriers).
• Males need one copy on the X (so men are more prone to it)

Huntington’s Disease

• only need one dominant disease in order to have it

Question 12

64. Know how to read a pedigree chart and be able to interpret the answers for (a) reading generations, (b) reading male from female, (c) knowing if someone has a disease, and (d) being able to figure out if the disease is recessive or dominant.

Question 13

65. According to the video Incomplete Dominance, Codominance, Polygenic Traits, and Epistasis, what is the definition of codominance?

Answer 13

Codominance - alleles work together

Question 14

67. According to the video Incomplete Dominance, Codominance, Polygenic Traits, and Epistasis, what are polygenic traits?

Answer 14

Polygenic Traits - many genes code for one trait

Question 15

68. According to the video Incomplete Dominance, Codominance, Polygenic Traits, and Epistasis, both height and skin color can be influenced by ___________ factors. ____________ can affect your height and spending a lot of time in the sun can affect your ___________. However, it cannot affect your genetics for a trait. Fill in the blanks.

Answer 15

1. Environmental

2. Nutrition

3. Skin color