9.28 Gametogenesis

Question 1

in meiotic division, the cells go from 2n to ___, then after the first cell division is is ___, and after the second, it goes to ___

Answer 1

4n (92 chromosomes)
2n (46 chromosomes)
1n (23 chromosomes)

Question 2

in the follicle, an oocyte is surrounded by __________ cells, which secrete _______ that become the zona pellucida

Answer 2

granulosa

glycoproteins

Question 3

what is the zona pellucida? why is it important?

Answer 3

it is a jelly-like coat around the oocyte, which is a central docking region for sperm

Question 4

in oogenesis, one precursor cell gives rise to _____ ovum (egg) and 2 or 3 ____________

Answer 4

one

polar bodies

Question 5

oocytes start primary meiosis before birth, primary meiosis is completed only upon ________. Now, the oocyte is __n and there is a _______ that is also __n

Answer 5

puberty
2n
polar body that is also 2n

Question 6

During _______, the second meiosis occurs, and is only completed upon ________. Now, we have a __n oocyte.

Answer 6

ovulation
fertilization
1

Question 7

in spermatogenesis, one germ cell gives rise to ____ sperm.

Answer 7

4

Question 8

spermatogenesis takes place in _______________ of the testes. They start on the outside, mature, and get released into the _____. _____ cells help this process.

Answer 8

seminiferous tubules
lumber
sertoli

Question 9

Down’s syndrome is caused by:

Answer 9

an extra copy of chromosome 21.

Question 10

The extra copy of chromosome 21 in Down’s syndrome resulted from abnormal _______ division

Answer 10

meiotic

Question 11

Patau’s syndrome is also called __________. It is a copy in chromosome ___ and is usually not compatible with life.

Answer 11

trisomy 13

13

Question 12

This disease occurs when a single X chromosome is inherited instead of 2.

Answer 12

Turner syndrome

Question 13

what are some of the manifestations of Turner syndrome?

Answer 13

short stature, webbed neck, reduction in secondary female characteristics, sterile.

Question 14

an extra copy of the X chromosome in males (XXY)

Answer 14

Klinefelter syndrome

Question 15

what is the translocation between Ch13 and Ch14 called?

Answer 15

Robersonian translocation

Question 16

in Robersonian translocation, what chromosomes are rearranged? They make a _______________ at the centrosome.

Answer 16

13 and 14

fused chromosome at their centrosome.

Question 17

People with Robersonian translocations are usually _____ since it can cause uneven meiosis.

Answer 17

sterile

Question 18

what are some main causes of male infertility?

Answer 18

absence of sperm, reduction in number, or production of defective sperm

Question 19

what are main causes of female infertility?

Answer 19

failure of oocyte maturation or release.

blockage of egg transport to fallopian tubes.