cell division🍇 Flashcards
why is mitosis important
tissue repair and replacement, growth, asexual reproduction, development
what happens in g1
cell grows and prepares for dna replication, synthesis of protein for organelle production, replication of organelles
what happens in s
dna is replicated ready for mitosis
what happens in g2
cell finishes growing and prepares for cell division
how is go entered
through g1 phase
what is g0
cell arrest, may be temporary or permanent
g1 checkpoint
checks for nutrient, growth factors and dna damage
what happens if fail g1
enters g0
g2 checkpoint
checks for cell size and dna replication
if pass g2 checkpoint
start mitosis
what happens if fails g2 checkpoint
repair damaged dna to prevent being transmitted to daughter cells
metaphase checkpoint
checks for chromosomes spinal fibres
what happens if fails metaphase checkpoint
arrests cell cycle at m phase until all chromosomes area aligned on spindle
centromere
renters chromatids
are chromatids identical
yes
what are homologous chromosomes
same size, genes at same loci (position)
how do prokaroytics replicate
binary fision
what happens in prophase
chromatin coils and condenses to form chromosomes, nucleolus disappeared and nuclear membrane breaks down, microtubules form spindle fibre shaped structures
what happens in metaphase
chromosomes Allin at equator,spondle fibres attached to centromere
what happens in anaphase
chromatids separate, shingle fibres contract pulling chromatids (centromere first) to opposite pole of cell
what happens in telophase
chromatids assemble at opposite sides of poles on spindle fibres and detach from spindle fibres, chromosomes uncoil and decondense to chromatids, neuclear membrane reforms at each poles
cytokinesis in animal cells
cell surface membrane pulled inwards by cytoskeleton until close enough to fuse around middle forming 2 cells
cytokinesis in plant cells
vesicles from Golgi begin to assemble in same place metaphase plate formed, vesicles fuse with each other and cell surface membrane divide in 2, new cell wall forms along new section of membranes
meristem
where plant growth occurs
mitosis vs meiosis daughter cells
mitosis 2 meiosis 4
is mitosis hap or dip
diploid
is meiosis hap or dip
haploid
mitosis vs meiosis gamete or somatic (body) cell
mitosis somatic, meiosis gamete
why is meiosis important
production of gametes for sexual reproduction
what does meiosis go from
diploid to haploid
prophase 1
chromosomes form, homologous chromosomes are very close togheter so the crossing over of non sister chromatids occurs creating new gene combinations
bivalent
pair of homologous chromosomes
synapsis
homologous chromosomes pair up to form a bivalent
chiasmata
where homologous chromosomes are held togheter
metaphase 1
bivalents line up along equator of the spindle, with spindle fibres attached to centromeres, the maternal and paternal chromosomes in each pair position themselves independently of the others which is independent assortment
anaphase 1
mictotubles pull whole chromosome to opposite end of spindle
telophase 1
nuclear envelope reforms around two groups of chromosomes
prophase 2
chromosomes condense, nuclear membrane breaks down, no crossing over
what is a stem cell
an unspecialised cell that is capable of division of differentiation to become other cell types
what happens if cell cycle to slow
ageing
what happens if cell cycle to fast
tumors
self renewal
continuosly divide and replicate, important to maintain stem cell pool
why is cell differential important
replaces dead or damaged cells
potency
have capacity to differentiate into specialised cell types
what qualities are import in unspecialised cells
self renewal and potency
totipotent
differentiate into any cell type, source is fertilised egg or zygote
pluripotent
they can different into all tissue types but not whole organism, present in early embryos
multipotent
forma range of cells within tissue, found in many places bone marrow adipose tissue, cord blood
