Mitosis, meiosis, cell cycle, cancer Flashcards
Define cell division
the process cells use to make more cells
what is the purpose of cell division (4)
growth, healing, cell replacement, reproduction
what types of cells does mitosis occur in
stem cells
what types of cells does meiosis occur in
germ or sex cells
describe the genome of eukaryotes
small and linear, dna found in nucleus
in eukaryotes, where is the dna found
in the nucleus
describe the genome of prokaryotes
large and circular, dna found in cytoplasm
in prokaryotes. where is the dna found
in the cytoplasm
what is the order in which the cell cycle occurs
G1, S, G2, M, Inter
what is the G1 phase
growth, cellular metabolism
specific regulatory proteins are made and activated. once activated, these proteins (kinases) then promote the activity of enzymes that synthesize dna
what is the S phase
synthesis- dna replication aka chromosome duplication
which step of the cell cycle is for the chromosome duplication
S (synthesis)
what is the g2 phase
preparation for mitosis
size and protein content of the cell increase
which stage of the cell cycle gets the cell prepared for mitosis
g2
what is the m phase
mitosis : chromosomal separation and cytokinesis
lasts about an hour
what is the interphase
the time between successive mitosis
replication of dna, increase3in cell size so each daughter cell receives sifficient cytoplasm
what is g0
quiescente cells that exit the cell cycle because they do not need to be replicated
what happens in mitotic cell division
a single parent divides into two daughter cells
what are the steps of mitosis
prophase, pro metaphase, metaphase, anaphase, telophase, cytokinesis
what happens in prophase
chromosomes condense. chromosomes radiate microtubules and migrate to opposite poles
what happens in pro metaphase
microtubules of the mitotic spindle attach to chromosomes
what happens in metaphase
chromosomes align in centre of cell
what happens in anaphase
sister chromatids separate and travel to opposite poles
what happens in telophase
nuclear envelope re-forms and chromosomes decondense
describe cytokinesis
contractile ring cuts one cell into two
what is ploidy
the number of complete sets of chromosomes in a cell
do ploidy levels in mitosis change
amount of dna changes but not the ploidy level
describe meiosis
diploid to haploid: two cell divisions: one mother cell turning into four unique daughter cells
mitosis results in
two identical daughter cells
meiosis results in
four unique, haploid daughter cells
what are the steps of meiosis
pmat(homologous chromosomes separate) pmat(sister chromatids separate)
describe prophase1 in meiosis
chromosomes become visible, homologous chromosomes continue to condense, each pair forms a bivalent, nuclear envelope begins to break down
describe anaphase 1and telophase1 in meiosis
homologous chromosomes separate, daughter cells are ready to move to prophase 2
describe metaphase 1 in meiosis
23 pairs of homologous chromosomes aligned in centre, mitotic spindle attached to mono-orientated kinetochores on sister chromatids, recombination occurs between homologous chromosomes
what phase does recombination occur in
metaphase 1
three similarities between meiosis and mitosis
mitotic spindles attached to both sister chromatids
separation of sister chromatids
alignment of al chromosomes along equilateral plate
three differences between meiosis and mitosis
only one of the homologues in metaphase 2
only recombined chromosomes in meiosis
half the number of chromosomes in metaphase 2
why can’t cell division occur all the time
uncontrolled division is dangerous and can lead to cancer
what controls the cell cycle
proteins (cyclins) and enzymes that appear in a cycle fashion
what is the dna replication checkpoint
checks for the presence of unreplicated DNA at the end of G2
what is the dna damage check point
checks for damaged dna before the s phase
what s the spindle assembly checkpoint
checks for all chromosomes being attached to the spindle before the cell progresses with mitosis
order of the cell cycle checkpoints
dna damage check point (before s)
dna replication checkpoint (before m)
spindle assembly checkpoint before mitosis
how does the dam damage checkpoint work
dna damage activates protein kinases that phosphorylate P13 (protein found in nucleus), then p13 acts as a transcription factor that turns on gene that inhibits the cell cycle.
define oncogene
cancer-causing gene
descrive pro-oncogenes
normal genes important in cell division that have the potential to become cancerous if mutated
describe a tumor surpressor
genes that encode proteins whose normal activities inhibit cell division
how do prokaryotic cells divide
binary fission
what is FTSZ
protein present in the genomes of diverse bacteria, also evolutionarily related to tubulin
what is tubulin
makes up the dynamic microtubules found in eukaryotic cells
histones
organized dna, packages chromospmes
what is a centromere
holds chromatids together
what is a mitotic spindle
created outside the nucleus, made up of microtubules that pull the chromosomes into separate daughter cells
what is tubulin dimers
assemble around centromere, which form the microtubules that radiate from the centrosomes. form the mitotic spindle
what is the contractive ring
ring of actin filaments that pinch cytoplasm
what is the chiasmata
visible manifestation of a crossover; the physical breakage and reunion between non-sister chromatids
define bivalent
two pairs of sister chromatids
meiosis 1
sometimes describes as reductional division because it reduces the number of chromosomes in daughter cells by half
which protein controls passage through the cell
protein phosphorylation
what are kinases
proteins that phosphorylate other proteins (enzymes)
what are cyclins
proteins that activate kinases
g1 cyclin
activates a protein that promotes the expression of histone proteins needed for packaging the newly replicated dna
S cyclin
necessary for the cell to initiate dna synthesis. activates enzymes and proteins necessary for dna replication.
cycin
triggers breakdown of the nuclear envelope, as well as proteins that regulate the assembly of tubulin into microtubules, promoting formation of the mitotic spindle
