D2.1 Flashcards
cytokensis
cell division
animal cytokensis steps
- cleavage furrow forms in cell centre
- actin and myosin proteins form a parallell ring around plasma membrane
- this also forms in cell centre
- contractions in protein pulls the membrane together causing seperation
plant cytokensis steps
- vesicles carrying carbs, lipids and proteins make 2 plasma membranes
- vesciles carrying pectin and cellulose form new cell wals in centre called cell plate
- cell splits
process of oogensis
oogonium - mitosis 2 x in womb
a diploid cell - secondary oocyte undergoes meosis. there is 2 haploids.
one is called the first polar body and like gets reabsorbed
- the one that survived mesosis again and forms ovum
second polar body leaves
processes of mesis and mitosis
i
P
m
A
T
c
interphase
both stages of growth getting ready to split happens here
growth 1
dna replication
growth 2
when does DNA replication happen
during interphase
dna replication process
- chromosone
- replicates and becomes cromatid with the two sisters
- splits and is still the same chromosone
purpose of histones
supercoil dna to form cromatin during prophase
spindle mictrotubules
- attatch tublin to the ends for growth
- motors in the centre called kinetochore on the chromosones atttatch tubules
two types of un even splitting
- ooegensis
- budding in yeast
when does nuclesus divide
interphase
before the cell devides
if nuclesus doesnt split then the cells will be anucleate and cant survive
prophase mitosis
- early prophase is the condensation of dna into chromatids
- sister cromatids form
- centrioles move to either end of the cell
- mictrotubules begin to grow
- late the chromosones fully condense and nuclear membrane breaks down
metaphase mitosis
- centrioles meet opposite ends
- spindles grow
- chromosones line up in crentre
- spindles attatch to centromere, specifically kinetochores
anaphase mitosis
- the sisters separate
- spindles shorten to pull to opposite ends
- chromatids become chromosones
- pulled to opposite poles
telophase mitosis
- chromosones decondense
- nucler membranes reform
- nuceloli form
how do IPMAT look in a mitroscope
- interphase nucleus is a dark circle, no chromosones visible
- prophase chromosones vibisbe, membrane breaks
- metaphase see the alignment
- anaphase v shape structures move to poles
- teolphase, splitting anc consesing
what does mitosis produce
two diploid cells with identical chromosones
goes from 1 chroatid - 2 chromatid - 1 but remains diploid the whole way
what types of devison is meosis
reduction divison
the mothers deiploid halfs to form two haploid
homologous chromosones
pairs of chromosones that are similar and thus pair up in meosis 1
they have the same genes but different allels
meosis prophase 1
- chromosones condense at this point theres two chromatids
- they meet their pairs
- this is where condesning happens
metaphase 1 meosis
- chromosones align with their pair in the middle
- spindle fibres attatch to centromere, kienochore
anaphase 1 meosis
- homologous pairs are separted and pulled to opp ends of cell
telophase 1 meosis
- the cell is now haploid.
- there is two cells with half the number of chromosones
- they are still chromatids with their sister
prophase 2 meosis
- no crossing over or pairs
- dna doesnt replicate
- spingles grow again
metaphase 2 meosis
- re lign up
anaphase 2 mesosis
- sister cromatids seperate like in mitosis
telophase
- the cell splits
- dna decondeses
- each is different
trisomy
an extra chromosome
when does none disjunction occur
when chromosones dont split properly in anaphase 1 or 2
consequence of none disjucntion
when the cells dvide one can end up with extra chromones, and one can end up with none
down syndrome
during anaphase 1, the 21st set of chromosones fails to seperate and there is 47 instead of 46
variation - crossing over
- happens when homologous chromosones pair up
- they are bivalent, with one from each poarent
- chromosones break down and re join
- jeans exchnage from each parent
- new combinations
variation - random orientation of bivalents
when they line up during metaphase they can line up in any order, this determins what genes are inherited into each cell
this process is completly random and independent
gives 8.000.000 plus posibilities
solvent
liquids that can dissolve other substances to make solutions
solutes
the dissolved substance in solutions
solvatation
the process of dissolving. water does this though forming hyrogen bonds with molecules - other polars
hyerpotonic solution
more solute in solution than thing(high outside low inside)
- shrinks
- net movement out of thing
hypotonic solution
less solute in solution than thing
(high inside low outside)
- expands/burst
- net movement of water in thinf
isotonic solution
the same concentration as the thing
- same same
- no net movement
uniceullular cells are hyper or hypo
hypertonic to environment meaning they have more solute in the cell than environment so the use CONTRACTILE VACUOLES to prevent bursting
in animal cells solutions are
kept isotonic to the cell
hypotonic solution cell wall
- water centres cell into vacuole
- turgor pressure increases beacuse protoplast expands
- cell becomes fully turgid
- walls prevent bursting
- without turgour pressure plants cant stand tall and wilt
in a hypertonic solution w cell wall
- colume decreases
- protoplast shrinks
