Genetics Midterm Review Sheet (Sarah)

Question 1

Huntington disease is the result of a HAPLO-insufficient mutation.

Answer 1

False

Question 2

Klinefelter syndrome (when an individual has GENOTYPE XXY) can be the result of non-disjunction in Meiosis 2 of the father. (Aka: father can only get XYY)

Answer 2

False

Question 3

What is the difference between trisomy and triploidy? Give a short definition of each and indicate what each means in terms of “n”. (Remember “n” refers to the number of chromosomes)

Answer 3

Trisomy: Has one extra copy of chromosome, causing developmental abnormalities.

2n+1

Triploidy: Has an extra third copy of all chromosomes, and is often always fatal.

3n

Question 4

Answer the following questions about a cell that is 2n=4 in mitosis.

How many chromatids are present in the metaphase plate?

Answer 4

8

Question 5

Answer the following questions about a cell that is 2n=4 in mitosis.

How many bivalents (CHROMOSOMES) are present?

Answer 5

0 because there are no homologous in mitosis/tetrads

Question 6

Answer the following questions about a cell that is 2n=4 in mitosis.

What are being separated at anaphase?

Answer 6

Sister chromatids

Question 7

Answer the following questions about a cell that is 2n=4 in Meiosis:

How many chromatids are present on the metaphase plate?

Meiosis 1:
Meiosis 2:

Answer 7

M1: 8
M2: 4

Question 8

Answer the following questions about a cell that is 2n=4 in Meiosis:

How many tetrads are present?

Meiosis 1:
Meiosis 2:

Answer 8

M1: 2
M2: 0

Question 9

Answer the following questions about a cell that is 2n=4 in Meiosis:

What are being separated at anaphase?

Meiosis 1:
Meiosis 2:

Answer 9

M1: homologous
M2: sister chromatids

Question 10

Galactosemia is a RECESSIVE human disease that is treatable by restricting lactose and glucose in the diet. Sally Smithers and her husband are both HETEROZYGOUS (a/A or B/b) for the galactosemia gene.

Sally is pregnant with twins. If she has fraternal twins (2 events)/(non-identical) twins, what is the probability that both girls will have galactosemia?

Answer 10

1/21/21/4**1/4= 1/64

Question 11

Galactosemia is a RECESSIVE human disease that is treatable by restricting lactose and glucose in the diet. Sally Smithers and her husband are both HETEROZYGOUS (a/A or B/b) for the galactosemia gene.

If she has identical twins (1 event) what is the probability that both girls will have galactosemia?

Answer 11

1/2*1/4=1/8

Question 12

Galactosemia is a RECESSIVE human disease that is treatable by restricting lactose and glucose in the diet. Sally Smithers and her husband are both HETEROZYGOUS (a/A or B/b) for the galactosemia gene.

If Sally and her husband have four children, what is the probability that none of the four will have galactosemia? Assume that there are NO twins.

Answer 12

3/43/43/4*3/4=81/256