Lecture 19

Question 1

Heterogametic sex

Answer 1

Males XY

Question 2

Homogametic sex

Answer 2

Females XX

Question 3

Y chromosome

Answer 3

Not man genes on it but determines maleness in humans

Question 4

X chromosome

Answer 4

Larger chromosome with a large number of genes on it

Question 5

Sex linked genes on which chromosomes

Answer 5

X chromosomes

Question 6

Non sex chromosomes called what

Answer 6

Autosomes

Question 7

Barr body

Answer 7

Inactive condensed chromatin remains inactive for a cell- lines progeny

Question 8

Females have 2 X chromosomes, while males have 1, what happens in women

Answer 8

One of the X chromosomes is always inactivated to form a barr body

Question 9

X inactivation is a cell -line specific trait

Examples

Answer 9

Calico cats with orange and black patches result from inactivation of one of the 2 X chromosomes in the skin

Question 10

SRY gene

Answer 10

Gene on the Y chromosome

Master switch that directs development of maleness at an early stage of embryonic development

Basically
Sex determining region of the Y chromosome

Gene codes for sex determining region Y protein

Question 11

How long for SRY gene to become active

Answer 11

Male embryo the tissues that form reproductive structures don’t begin to differentiate into testes until SRY becomes active

6-8 weeks

Question 12

Is the SRY a pleiotropic gene

Why

Answer 12

Yes

Affects many tissues in the embryo

Suppresses female differentiation

Also works to develop and maintain secondary sex characteristics in males

Question 13

One of the best known X linked disorder

Answer 13

Hemophilia

Blood doesn’t clot normally, so any cut or bruise can be life threatening

Question 14

How to do sex linked traits

Answer 14

Dominant H
Recessive h

X^H X^h cross them

Question 15

Hemizygous

Answer 15

Only receive one copy of a sex linked gene

Presence of one normal allele will mean ur chilling

One bad one and ur cooked