9.28 Gametogenesis Flashcards
in meiotic division, the cells go from 2n to ___, then after the first cell division is is ___, and after the second, it goes to ___
4n (92 chromosomes)
2n (46 chromosomes)
1n (23 chromosomes)
in the follicle, an oocyte is surrounded by __________ cells, which secrete _______ that become the zona pellucida
granulosa
glycoproteins
what is the zona pellucida? why is it important?
it is a jelly-like coat around the oocyte, which is a central docking region for sperm
in oogenesis, one precursor cell gives rise to _____ ovum (egg) and 2 or 3 ____________
one
polar bodies
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
puberty
2n
polar body that is also 2n
During _______, the second meiosis occurs, and is only completed upon ________. Now, we have a __n oocyte.
ovulation
fertilization
1
in spermatogenesis, one germ cell gives rise to ____ sperm.
4
spermatogenesis takes place in _______________ of the testes. They start on the outside, mature, and get released into the _____. _____ cells help this process.
seminiferous tubules
lumber
sertoli
Down’s syndrome is caused by:
an extra copy of chromosome 21.
The extra copy of chromosome 21 in Down’s syndrome resulted from abnormal _______ division
meiotic
Patau’s syndrome is also called __________. It is a copy in chromosome ___ and is usually not compatible with life.
trisomy 13
13
This disease occurs when a single X chromosome is inherited instead of 2.
Turner syndrome
what are some of the manifestations of Turner syndrome?
short stature, webbed neck, reduction in secondary female characteristics, sterile.
an extra copy of the X chromosome in males (XXY)
Klinefelter syndrome
what is the translocation between Ch13 and Ch14 called?
Robersonian translocation