Single Factor Crosses III.

Question 1

Sex-linked traits:

Answer 1

Sex based biased in the inheritance of a trait.

Question 2

Why is the inheritance of sex-linked traits different from that of autosomal traits?

Answer 2

Both sexes have different sex chromosomes, compared to autosomal chromosomes.

Question 3

X & Y chromosomes behave like homologous pairs during:

Answer 3

Meiosis.

Question 4

Categories of genes on sex chromosomes:

Answer 4

Holandric Genes.
X-linked Genes.
Psudoautosomal genes.

Question 5

Why aren’t the X and Y chromosomes considered homologous pairs?

Answer 5

They don’t share the same genes.

Question 6

Holandric Genes:

Answer 6

Genes only found on the Y chromosome.

Question 7

X-linked Genes:

Answer 7

Genes that are only found on the X chromosome.

Question 8

Psudoautosomal Genes:

Answer 8

Genes that are found on both the X and Y chromosome.

Question 9

Many more ______ genes than Holandric or __________ genes.

Answer 9

X-linked genes.
Psudoautosomal.

Question 10

What genes don’t determine sex:

Answer 10

Psudoautosomal genes.

Question 11

What gene function in male determination:

Answer 11

Holandric Genes.

Question 12

SRY (Sex Determine Region on the Y) Gene:

Answer 12

Gene is only active during embryonic development.

The gene is expressed @ 7 weeks.

Produces a protein called TDF.

Question 13

TDF (Testis Determining Factor):

Answer 13

Acts on the developing gonad.

It is involved in Testis development.

Question 14

No TDF means:

Answer 14

Genes involved in ovary development are activated.

Question 15

Null allele of SRY (XY sex reversal):

Answer 15

SRY does not function.

XY genetic sex –> Female Genetalia.

Gonads are undeveloped.

At puberty, menstruation doesn’t start.

Question 16

X-linked Hypophosphatemia:

Answer 16

Traits produced by an x-linked dominant allele; mutant allele.

Ex: Vitamin D-resistant rickets.

Biased towards women.

Question 17

Rickets:

Answer 17

Low levels of vitamin D and Phosphate.

Question 18

Hemizygous:

Answer 18

An individual who has only one member of a chromosome pair or chromosome segment rather than the usual two.

Question 19

X-Linked recessive Traits:

Answer 19

Have a strong bias toward males in the inheritance of the trait.

Ex: Red-Green Colorblindness

Males are more likely to inherit.

Question 20

Cone cells:

Answer 20

Detect Light.

Question 21

Colorblindness:

Answer 21

Inability to perceive a color, or the abnormal perception of color.

Question 22

The population of Colorblindness in Northern Europe:

Answer 22

1:12 — Males
1:200 — Females.