Week 4 - The Chromosomal Basis of Inheritance

Question 1

What gene on what chromosomes codes for the development of male anatomical features?

Answer 1

The SRY gene on the Y chromosomes

Question 2

What happens to female X chromosomes during embryonic development?

Answer 2

In each cell, randomly, one of the X chromosomes will inactivate and condense into a Barr body.

Question 3

What is a barr body?

Answer 3

During embryonic development in females, one of the X chromosomes is randomly deactivated, forming a Barr body

Question 4

What are linked genes?

Answer 4

The physical location of two or more genes found of the same chromosome is called linkage.

Question 5

How do linked genes relate to the law of independent assortment?

Answer 5

Linked genes are always transmitted together, thus violating the law of independent assortment.

Question 6

How can geneticists predict if genes are linked using a testcross?

Answer 6

Using a homozygous recessive pairing, if the offspring differ from the 1:1:1:1 ratio, then linkage is likely

Question 7

What is aneuploidy?

Answer 7

Deviation from the usual chromosome number

Question 8

What is polyploidy?

Answer 8

More than 2 complete chromosome sets (e.g. triploidy, tetraploidy)

Question 9

What is polysomy?

Answer 9

More than 2 copies of a particular chromosome in a diploid cell

Question 10

What is monosomy?

Answer 10

Only one copy of a particular chromosome in a diploid cell

Question 11

What is trisomy?

Answer 11

Three copies of a particular chromosome

Question 12

What is trisomy 21?

Answer 12

Down Syndrome

Question 13

What chromosomal alteration causes Down Syndrome

Answer 13

Trisomy 21 (extra chromosome 21)

Question 14

What is Klinefelter’s Syndrome?

Answer 14

A condition where the child is born with an extra X chromosome

Question 15

What is the karyotype 47 XXY?

Answer 15

Klinefelter’s Syndrome

Question 16

What is Turner’s Syndrome?

Answer 16

A condition where a child is born with only 1 X chromosome.

Question 17

What is the karyotype 45 XO?

Answer 17

Turner’s syndrome

Question 18

What is the karyotype for Turner’s Syndrome?

Answer 18

45 XO

Question 19

What is the karyotype for Klinefelter’s Syndrome?

Answer 19

47 XXY

Question 20

What are the 4 alterations/deviations of chromosome structure?

Answer 20

Deletion = removes chromosomal segment
Inversion = reverses a chromosome segment
Duplication = repeats a chromosome section
Translocation = moves a section from one chromosome to a non-homologus chromosome.

Question 21

What is Cri Du Chat Syndrome?

Answer 21

A disorder resulting in mental impairment and leaves the child with a cat-like cry

Question 22

What is the karyotype 46, (5p-)?

Answer 22

Cri Du Chat Syndrome

Question 23

What is the karyotype for Cri Du Chat Syndrome?

Answer 23

46, (5p-)