cell cycle Flashcards
Mitosis during embryonic development
mitosis produces a stockpile of cells for embryogenesis
hyperplasia
organismal growth (growth of organs)
mitosis
Meiosis: important stuff you don’t already know
occurs only in germ line cells
functional cell numbers do not always increase
Cell Cycles subdivisions: Centrosomal cycle
a. centrioles duplicate during interphase
b. sister centrioles separate during prophase and come to lie opposite one another
c. centrioles form the poles of the spindle apparatus by serving as nucleation site for microtubule subcomponents
d. centrioles consis of a pair (typically) oriented perpendicularly to each other
Cell Cycles subdivisions: Nuclear Cycle
a. lamins A, B, and C are phosphorylated and disintegrate
b. nuclear bilayer dissolves
c. after mitosis, lamins are dephosphorylated and membrane reforms
important: the mitotic spindle’s microtubules will not connect to the centromeres of chromosome if nuclear envelope is present
Cell Cycles subdivisions: Cytoplasmic Cycle
G1 period
This cycle involves increase in volume to a critical mass.
Must occur BEFORE mitosis can occur
Normally this process occurs to replace worn out/damaged cells. During embryogenesis, the replication time is so short the cytoplasmic cycle barely occurs and cells get smaller
Cell Cycles subdivisions: chromosomal cycle
Involves replication of the DNA molecules contained with in the nucleus in the form of chromosomes
- DNA unwinds
- Opening of helix involves topoisomerases such as helicase
Cell Cycle (traditionally)
G1 or G0
S
G2
M (pro, meta, ana, telo)phase
What controls the progression through the cell cycle?
protein kinases that have been conserved from yeasts to mammals
G1 phase (card one)
Cell is 2N
Concentration of cyclin E increases
E-cyclin binds to inactive CDK2, forming MPF
MPF is activated at of this phase and leads to activities needed for DNA synthesis
Highly variable with regard to time
