Chapter 17 Flashcards
what are germ cells?
reproductive cells that have materials for initiating bodies in the next generation (immortal)
what are cytoplasmic determinants?
maternal substance already inside the cell that changes how the DNA acts for early development
what is special about nematode germ plasm?
contains a set of proteins that ensures the DNA doesn’t get activated
-prevents chromosome diminution!!
-gametes need ALL parts of chromosome
what is chromosome diminution?
fragmenting of blastomere so only small % of chromosome survives
-only in cells without germ plasm
what is the process of oocyte maturation?
- oogonium (mitosis)
- primary oocyte (starts meiosis 1)
- secondary oocyte & polar bodies (starts meiosis 2)
what is the fusome –> ring canals?
cytoplasmic bridge where nurse cells attach to the egg
-directional portal to allow the egg to get materials
what is the germarium?
nurse cells + egg formation
-contain follicle cells that set up polarity before fertilization
posterior: egg
anterior: nurse cells
what are the two ways the nurse cell and egg functions were discovered? how do they work?
in situ hybridization: probed to find mRNA
immunohistochemistry: fluorescent labeled antibodies to find proteins
what is the inert genome hypothesis?
cells become germ cells because they are forbidden to become any other type of cell
-stem cells are totipotent (potential to become anything)
-occurs because of germ plasm components that block transcription or translation
what are the four germ plasm components that block transcription?
gcl (makes germ cells)
pgc (pole cells, blocks RNA poly)
PIE-1 (inhibits enzymes)
piwi (needed for cell proliferation)
what are the three germ plasm components that block translation?
piwi
nanos (posterior end)
vasa (represses somatic cells, differentiation)
what are pole cells?
cells that migrate inward to be surrounded by germ line cells
-cells that have remain inert by cytoplasmic determinants
-found using VASA probe
describe frog oocyte maturation
takes 3 years
-needs a vitellogenic phase to accumulate proteins and materials needed for survival of the vulnerable baby when born for accelerated growth
what are the different parts of a lampbrush chromosome?
string: rDNA
branches: rRNA
what are cellular components in an oocyte besides DNA?
mitochondria
RNA poly
DNA poly
histones
DNTP
ribosomes
tRNA
morphogenical factors
cytoplasmic determinants
vitellogenin
what are some components made after fertilization?
cyclins
Vg1
cadherins
metalloproteinases (remove cell matrix)
actin
tubulin
reductase
how does oocyte maturation work in rabbits & minks?
ovulate during intercourse, no cycles
how does oocyte maturation work in deer?
estrus: ovulation triggered by weather
diapause: growth pauses until spring
what is the process of human oocyte maturation?
- stem cell divides via mitosis
- becomes a primary oocyte before being arrested - diplotene (prophase 1) BLOCK
-chromosomes are crossed over but cannot go into metaphase 1
-progesterone activates MPF through phosphorylation - metaphase 1 –> metaphase 2
-becomes a secondary oocyte before being arrested - metaphase BLOCK
-fertilization causes a release of Ca2+ that breaks down CSF - completion of meiosis 2
what is the process of spermatogenesis?
- spermatogonia
- primary spermatocytes
- secondary spermatocytes
- spermatids
————SPERMEOGENESIS (makes tails)———— - sperm & residual bodies
what is different about sperm and oocyte maturation?
spermatogenesis…
- meiosis initiated continuously
- 4 gametes produced
- completed in days or weeks
- no cell arrests
what are sertoli cells?
stretch b/w cells and controls the process of spermatogenesis and spermeogenesis
-makes GDNF
when during spermatogenesis are BMP-8 and GDNF important?
spermatogonia -> spermatocytes
what happens to BMP-8 and GDNF as the spermatogonia matures?
BMP-8: increase in amount as cells divides
GDNF: decreases in amount as cells divides (diluted out)
