Biochemistry - Cell cycle

schlseiden and schwann cell theory

every living organism is composed of one or more cells and new cells can only arise by division of pre existing cells (to reproduce cells must replicate chromosomes and segregate them into two daughter cells)

length of G1

12 hours

when G1 occur

immediately after mitosis

what happens in G1

duplication of cell contents not chromosomes (eg enzymes nucleotides)

cell cycle phases in order

G1 / S / G2 / M

What does S stand for

synthesis

what happens in S

dna replication (chromosome synthesis)

how long is S

6 hours

how long is G2

6 hours

2 activities in G2

make protein for spindle / assemble spindle for mitosis

cytokinesis

division of cell into 2 identical daughter cells

how long mitosis

30 minutes

what happens in G0

cells leave cell cycle and non longer divide / fully differentiated so produce function

cell synchrony

synchronise population of cells so that they are all each cell in culture is at same part of cell cycle at same time to understand which processes occur in which part of the cell cycle

name the 2 types of synchrony

natural / experimental

2 types of experimental synchrony

selective / induced

2 examples natural synchrony

sea urchin system / slime mould

how does selective synchronization work

isolate subpopulation of cells that are at the same point in cell cycle by exploiting a cellular property that changes as cells go through the cycle

3 examples of selective experimental synchrony

centrifugation (sort cells by size, density, shape) / mitotic selection / individual cell selection

2 examples of centrifugation (selective experimental synchrony)

equilibrium density gradient centrifugation / differential rate centrifugation

example of species where differential rate centrifugation carried out

fission yeast (mature cylindrical / growth increase in length not diameter - length indicates position in cell cycle)

example mitotic selection (experimental selective synchrony)

Chinese hamstery ovaries

example individual cell selection (experimental selective synchrony)

micromanipulation

2 examples experimental induced synchrony

repetitive heat shocks / light-dark cycles / reversible inhibition of DNA synthesis

what repetitive heat shocks used on (induced synchrony)

animals

what light/dark cycles used on (induced synchrony)

plants

example of what used to study cell cycle regulation

frog/mous oocyte meiosis

MPF

mitosis/maturation promoting factor

what is MPF required for

entrance into mitosis

most dominant cell cycle phase

G1

cell cycle phase dominance in order

M / S - G2 / G1

where is MPF purified from

function cdc25

encodes a protein phosphatase

function wee1

encodes a protein tyrosine kinase (regulates mpg by phosphorylation and desphosphorylation)

nuclear lamina

filamentous network particularly dense near inner nuclear membrane that s composed of proteins located inside the nucleus

filamentous meaning

thread like, thin in diameter

what is nuclear lamina mainly composed of x2

lamina a / lamina b

homodimer

protein composed of 2 polypeptide chains identical in order number and kind of amino acid residues