gametogenesis

Question 1

when does meiosis occur in testicle-having individuals

Answer 1

during puberty and adulthood

Question 2

what would happen to the production of sperm if we prevented mitosis from happening (but allowed meiosis to continue)

Answer 2

sperm production would continue normally, then halt

Question 3

timeline of spermatogenesis and spermiogenesis

Answer 3

spermatogonium -> primary spermatocyte -> secondary spermatocyte -> spermatids -> sperm (spermatozoa)

Question 4

secondary spermatocytes are

Answer 4

haploid

Question 5

what is spermatogenesis

Answer 5

diploid cell becoming 4 haploid spermatids, physical maturation of spermatids into sperm

Question 6

what direction do germ cells go to be mature sperm

Answer 6

cells migrate from basement membrane toward lumen of seminiferous tubule as they develop

Question 7

why do we have an acrosomal cap

Answer 7

breaking through egg’s membrane, has enzymes to break through zona pellucida

Question 8

why do we have many mitochondria around the neck

Answer 8

power and propulsion, ATP

Question 9

why do we need to reduce cytoplasm

Answer 9

extra weight, drag

Question 10

what is production rate of sperm

Answer 10

1000 per sec

Question 11

what percentage of sperm in a sample are normal

Answer 11

5-15%

Question 12

when does meiosis occur in ovary-having individuals

Answer 12

in the developing fetus, during puberty, in adulthood

Question 13

how many gametes result from a single round of meiosis in ovary-having individuals

Answer 13

1

Question 14

oogenesis

Answer 14

meiosis in ovary-having people arrests in 2 different time points:
-prophase I (at birth)
-metaphase II (at ovulation)
-completes after fertilization

Question 15

oogenesis 2

Answer 15

oogonium –> primary oocyte –> secondary oocyte –> ovum –> fertilized egg (zygote)

Question 16

a hormone moves through the plasma membrane and activates a receptor in the cytoplasm. this hormone is likely a

Answer 16

steroid

Question 17

what are peptides

Answer 17

surface receptors

Question 18

what are steroids

Answer 18

surface and intracellular receptors

Question 19

what would happen to sperm production if there were a decrease in FSH levels

Answer 19

decrease

Question 20

primary oocyte peak numbers

Answer 20

-peak # (~7 million) of primary oocytes occurs around 20 weeks gestation
-# at birth ~1 million
-arrested in prophase 1 until puberty
-# at onset of puberty ~200,000
-small # start ‘maturing’ each month to finish meiosis I

Question 21

what do sertoli cells help with

Answer 21

secrete proteins to support sperm production

Question 22

why does constant release of GnRH from the hypothalamus drop levels of LH and FSH

Answer 22

constant release of GnRH uncouples receptor from second messenger pathway and internalizes receptors

Question 23

instead of constant release of GnRH, how does it need to be released

Answer 23

pulsatile generation via neurons called pulse generator of GnRH

Question 24

what is the feedback loop for KISS neurons

Answer 24

-KISS neurons release KISS peptides which increase GnRH release
-negative feedback from sex steroids reduces KISS neuron excitability = less KISS peptide = less GnRH release