Part A: Lecture 2 Flashcards
gametogenesis (def.)
meiosis when it produces gametes
meiosis in males
spermatogenesis (diploid -> spermatid -> sperm)
meiosis in females
oogenesis (diploid -> oocyte -> egg)
spermatogenesis (def.) + steps (2)
haploid cells grow flagella to be motile
-step 1: meiosis
-step 2: maturation
spermatogenesis begin entering meiosis at _____
puberty
spermatogenesis takes how long?
60 days
spermatogenesis produces __ gamates
4
oogenesis produces how many gametes?
a single large haploid cell rather than four little haploid cells
In humans, oogenesis produced ___ discarded cells named?
2 polar bodies
oogenesis in humans start in ___ and _____
fetus and pauses in prophase I when DNA replicated and condensed
oogenesis during puberty
-once a month, one or two cells resume meiosis, enter oviduct, and can be fertilized
pronuclei (def.)
nucleus of a sperm/egg cells during the process of fertilization
fertilization (sperm + egg)
sperm: 23 paternal chr.
egg: 23 maternal chr. cytoplasm and mitochondria
fertilization cleavage timeline
-egg -> morula -> blastocyst
DNA replication starts at ____ (fertilization)
-zygote stage
Genes turn on at ____ (fertilization)
-the 4 cell stage
zygotic genome activation (def.)
initiation of gene expression after fertilization at the 4 cell stage
hatching (def.)
blastocyst expelled out of the zona pellucida
implantation
-blastocyst enters side of uterus
inner cells of blastocyst becomes the ___
embryo
outer cells of blastocyst becomes the ___
membranes and placenta
fluid cavity of blastocyst becomes the ___
amniotic cavity/fluid
cells in amniotic fluid are from ____
the embryo
dizygotic (non-identical) twins
2 zygotes (2 placenta + embryos)
monozygotic (identical) twins (2 types)
- splitting at 2-cell stage: separate placentas
- splitting inner cell mass: 1 placenta
twins are rare but one type of twins is rarer: ___
monozygotic twins
embryogenesis involves ___ to make ____
-cell differentiation, cell division
-organs
