ch 5- cell division Flashcards
homologous chromosome pairs
two diff versions of the same chromsome number
one from mom and one from dad
dyad
replicated chromosomes containing two sister chromatids that look like an X
connected by centromeres
what connects sister chromatids
centromeres
kinetochores
proteins on the side of centromeres that help microtubules pull sister chromatids apart during cell idvision
karyokinesis
division of the nucleus
how many autosomes do we have (chromosomes)
22 pairs
gametes
haploid cells (sperm and eggs)
germ cells
diploid cells that divide by meiosis to produce gametes
gametocyte
euk germ cell
can either divide to make more gametocyte or produce gametes
what are somatic cells
ALL BODY CELLS EXCEPT GAMETES (haploid)
what are the parts of interphase
G1
G0
S
G2
90% of the cell cycle happens during what
interphase
what happens during G1
cell grows
checks for favourable conditions
if unfavourable it will enter G0
what is G0
cells still carry functions but stop cell cycle and do not divide
what happens during S phase
cell replicates its genome
centrosome replicates
what happens during G2
continues to grow
check DNA for errors
checks for MPF- mitosis promoting factor (maturation promoting factor)
organelles replicated
what are the fucntional limitations that lead to cell division
when surface area: volume ratio is too low and when the genome to volume ratio is too low
what are the cell specific checkpoints
G1- check for facourable conditions
end of G2- check for errors in DNA and MPF levels
M- check for chromosomal attachment to spindle fibres
CDKs
phosphorylate certain substrates to signal cell cycle progression
they depend on cyclin which cycles through stages of synth and degradation
growth factors
bind to receptors in th eplasma membrane to signal for cell division
density dependent inhibition
halting cell division when density of cells is high
anchorage dependence
cells divide only when attached to an external surface
what forms the spindle apparatus
the MTOCs
MTOCs
organize spindle appartus
ONLY IN EUK-
made up of centrosomes- pair of centromeres- ORGANELLES
What are the types of microtubules in the spindle appartus
kinetochore microtubules
astral microtubules
polar microtubules
kinetochore microtubules
extend from centrosomes and attach to kinetochores on chromosomes
astral microtubules
extend from centrosomes to the cell membrane to orient the spindle apparatus
polar microtubules
extend from the two centrosomes and connect with each other - push centrosomes to opposite ends of the cell
pericentriolar material
surrounds centrioles and is responsible for microtubule nucleation (anchoring tubulin to start microtubule extension)
prophase
chromatin condenses
nucleolus and nuclear envelope dissapear
spindle apparatus forms
prometaphase
nuclear envelope fragments
spindle apparatus microtubules attach to kinetochore of chromosomes
when does chromosomes number double
during anaphase
cleavage furrow
forms in late anaphase in animal cells
contractile ring of ACTIN microfillaments and myosin motors that pinches the cell into two
cell plate
in telophase in plant cells
created by vesicles form the golgi apparatus and forms middle lamella (cements plant cells together)
binary fission
no s phase
cells replicate genome DURING cell division
NO SPINDLE APPARATUS
Meiois I vs II
I- homologous chromosomes separate
II- sister chromosomes separate - reductional division
when does crossing over occur
prophase I
bivalent
tetrads - homologous chromosomes paired up - happens during synapsis
between these homologous chromosomes, there is a synaptonemal complex
chiasmata
when two chromosomes of a homologous pair cross over during synapsis
s phase chromosome numbers
there are 46 chromosomes- after duplication- there are still 46 chromosomes but 92 chromatids
during anaphase- we have 92 chromosomes and 92 chromatids and results in 46 chromosomes and 46 chromatids after separation (diploid)
number of chromosomes and chromatids in mitosis
prophase - 46. 92
metaphse- 46. 92
anaphase- 92. 92
telophase- 92. 92
separated cells have 46 chromosomes and chromatids
number of chromosomes and chromatids in meiosis I
prophase - 46. 92
metaphse- 46. 92
anaphase- 46. 92
telophase- 46. 92
separated cells have 23 chromosomes and 46 chromatids
number of chromosomes and chromatids in meiosis II
prophase - 23. 46
metaphse- 23. 46
anaphase- 46. 46
telophase- 46. 46
separated cells have 23 chromosomes and 23 chromatids
