CSF: cell division and cancer Flashcards
what makes up the miotic phase
mitosis plus cytokinesis
4 stages of meiosis 1
- prophase
- metaphase
- anaphase
- telphase
4 stages of meiosis 2
- prophase
- metaphase
- anaphase
- telophase
whats the difference between meiosis 2 and mitosis?
mitosis is not preceded by DNA replication
what are the three main parts of interphase
- growth and gap phase 1
- synthesis of DNA
- Growth or Gap phase 2
why do cells divide?
growth and development
tissue renewal
results in two ‘cloned’ daughter cells
during interphase
DNA replicates
during prophase
DNA condenses further in:
- two identical chromatids per chromosome - sister chromotids
during metaphase
sister chromatids line up
During anaphase
sister chromatids separate
daughter cells are
identical to parent cell
what are the points of mitotic checkpoints
Mitotic check points are molecules that check how the replication process is going
halt the reproductive process if DNA is faulty/damaged
what are the mitotic cell points
M, G1, G2
What are the key signals to pass G1
- undamaged DNA
- good cell size and nutrition
- appropriate signals are present
What are the key signals to pass M
- all spindles are attached
3 key molecules for G2 checkpoint
- cyclin
- cyclin dependant kinase
- M-phase promoting factor
what is the function of cyclin
protein that fluctuates throughout the cell cycle
what is cyclin dependant kinase (CDK)
kinase activated when attached to a cyclin
what is M-phase promoting factor
- Cycling/CDK complex
- key for G2 checkpoint
mutations in the cell cycle can cause what?
CANCER
cancer causing DNA changes can be
- small scale alterations (point mutations)
- gain/loss/translocation of chromosomes/genes
DNA changes can be results of
- aquired changes that target single cells i.e. carcinogens
- Inherited changes that target all cells - susceptibility genes
cancer genes effected by DNA changes are (2)
- proto-oncogenes
- tumour supressor genes
Proto-oncogenes function
stimulate cell proliferation
tumour suppressor genes
genes that keep proliferation in check
activation of proto-oncogenes is like?
pressing the accelerator
deactivation of tumour suppressor genes is like
a loss of brakes
Growth gap stage 1 (2 points)
- most cellular activities occur
- duration varies depending on cell type
Synthesis of DNA (3 points)
- DNA replicates
- strands separated at the hydrogen bonds holding nucleotides together
- new strands of DNA synthesised as opposite of each old strand
Growth Gap stage 2 (3 points)
- checks correct DNA synthesis
- prepares for the miotic phase (synthesis of proteins and enzymes + gathering reactants)
- replication of centrosomes is completed
meiosis vs mitosis - property
meiosis - only diploid cells
mitosis - diploid and haploid
meiosis vs mitosis - DNA replication
meiosis - during interphase, between meiosis 1 and 2
mitosis - during interphase before mitosis begins
Number of divisions in Meiosis
One inc. prop, prometa, meta, ana and telo
number of divisions in Mitosis
Two inc. prop, meta, ana, telo
synapsis of homologous chromosomes meiosis
occurs during phase 1 w/ crossing over between non-sister chromotids; resulting chiasmata hold pairs together due to sister chromatid cohesion
synapsis of homologous chromosomes mitosis
does not occur
meiosis vs mitosis - Number of daughter cells and genetic comp.
Meiosis - 4, each haploid (n); genetically dif from everything (parents and sisters)
Mitosis - 2, identical to parents w same number of chromosomes
3 sources of cellular variation
- independent assortment at metaphase
- crossing over at metaphase
- fusion between two gametes
