gametogenesis and Meiosis and mitosis Flashcards
Germ cells can only undergo meiosis
true or false
false can undergo both
meiosis is only completed in females only once the oocyte is fertilised
true or false
true
at 7 months what what stops making more of themselves and what process starts
oogonium and meiosis to make primary oocytes
Primary oocytes by puberty that number decreases
do males run out of oogonia
no
but females have a limited number of primary oocytes
which type of devision produces genetically unique cells
meiosis
mitosis - identical
which type of devision results in diploid cells
mitosis
haploid for meiosis
which type of devision only takes place at a certain period in an organisms life time
meiosis
are both devisions involved in sexual reproduction
yes
what are chromosomes
are linear structures with genes located at specific sites along them
what stages of mitosis
prophase
metaphase
anaphase
telophase
what happens in early prophase
condensing replicated chromosomes consisting of 2 sister chromatids
mitotic spindle forms as microtubules grow out of centrosomes(made of 2 centrioles) which begin to move away from each other
nuclear envelope intact
what happens in pro metaphase
microtubules emerge from centrosomes at poles of mitotic spindle and extend into nuclear region reaching the chromosomes
some of spindle attach to kinetochores
other spindle microtubules make contact with microtubules from opposite poles
nuclear envelope disappears
what is a kinetochores
proteins associated with chromosome where spindle attach to pull sister chromatids apart
what is metaphase
mitotic spindle fully formed and chromosomes are now midway between spindle poles lined at equator
what is anaphase
2 centromere of each chromosome come apart separating the sister chromatids.
Proteins of the kinetochores powered by ATP walk daughter chromosomes along microtubules to opposite poles.
Spindle attached to K shorten and spindle not lengthen
poles then move further apart
what is telophase
daughter chromosomes/ chromatid at spindle pole
nucelar envelope around individual chromosome form contractile ring
what is cytokinesis - creates cleavage furrow
cytoplasm divides by contractile ring of actin and myosin filaments creating a cleavage furrow
what is G1 phase
cell increase in size
S phase
DNA réplication occurs during this phase
G2
cell continues to grow and energy stores are duplicated
G0
cell has left the cell cycle
what is somatic cell
any cell that is not a sperm or egg cell
what cells can reenter the cell during an immune response
Lymphocytes
what happens in prophase 1
pairing and crossing over duplicated homologs ( bivalent) crossing over on bivalents - nuclear envelope breakdown - chiasma
nuclear envelope break down
metaphase 1
homolog pairs line up - would be chromatids in mitosis
anaphase 1
homologous chromosomes pairs separated moving all chromosome to each cell
telophase 1
nucelar envelope around chromosome
prophase 2
nuclear envelope gone
metaphase 2
chromosomes line up and separate
anaphase 2
sister chromatids separated , centrome divide
telophase 2
inherits chromatid from each chromosome
when does crossing over occur
prophase 1
what protein lattice holds homologous chromosomes together in early prophase 1 and in perfect alignments
synaptonemal complex
what is an oocyte
immature egg cell - prophase 1
in what stage of the cell cycle is a secondary oocyte formed and haploid
metaphase 2
spermatogonium
diploid cell twice mitosis and meiosis 1 and meiosis 2 to form 4 spermatids - haploid - then form mature spermatozoa
germ cell
any cell that gives rise to the gametes - diploid
when do germ cells arise
during the primitive streak
at what time to oogonium turn to primary oocyte
7 months
