chapter 6 cell division Flashcards
what stages does the cell cycle consist of?
Interphase, mitosis and cytokinesis
what happens in G1 of interphase?
growth and synthesis of new proteins/organelles. synthesis of new centrosomes start.
what happens in S of interphase?
DNA synthesis(semi conservative), DNA repair. centrosomes finish being made.
what happens in G2 of interphase?
rapid growth of cell, checking for DNA damage and making any needed repairs. Synthesises new molecules needed for division.
what happens at each checkpoint in the cell cycle?
G1: checks for cell size/DNA damage/growth factors
G2:cell size/DNA replication and damage
Spindle: chromosome attaches to spindle fibre in mitosis
what happens at G0?
if checkpoint isn’t reached the cell goes to G0 to continue growing but if there is an issue with the cell it goes into cell cycle arrest.
what is the first stage of mitosis and what happens in it?
prophase: cell has two pairs of chromosomes which have replicated to form two chromatids. DNA has condensed so sister chromatids are visible
what is the second stage of mitosis and what happens in it?
metaphase: chromatids line up in the middle of the cell, nuclear envelope breaks down, fibres appear in cytoplasm and form spindle fibres.
what is the third stage of mitosis and what happens in it?
early anaphase: each chromatid is attached to a spindle fibre at the centromere the spindle fibres shorten and pull them apart
what is the fourth stage of mitosis and what happens in it?
middle anaphase: chromatids are now separate so are chromosomes. these chromosomes migrate to opposite ends of the cell
what is the 5th stage of mitosis and what happens in it?
end anaphase: cytoplasm may begin to divide (still no nuclear envelope)
what is the final stage in mitosis and what happens in it?
telophase: nuclear envelope has reformed around each group of chromosomes, chromosomes become less distinct as DNA disperses, cytoplasm pinches in the middle forming a cleavage furrow. Mitosis is now complete as 2 new nuclei are formed.
what is the last stage after mitosis has finished and what happens?
cytokinesis: cytoplasm divides forming 2 identical diploid daughter cells
in plants what are the only cells which can undergo mitosis?
meristems
