mitosis and the cell cycle Flashcards
what are the three stages of interphase?
G1, S , G2
what happens during G1, S and G2 phases of interphase?
G1= growth and organelles replicate, RNA, enzymes and other proteins needed for growth are made
S= DNA synthesis
G2= more growth and new DNA that has been synthesised is checked for errors.
what is the longest phase of the cell cycle?
interphase
what is mitosis?
part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells,
each with the identical copies of DNA produced by the parent cell during DNA replication.
what is the pneumonic to remember cell cycle?
IPMAT
what is the order of the cell cycle?
interphase
prophase
metaphase
anaphase
telophase
cytokinesis
what happens during interphase (4)
-cell enlarges
-organelles replicate
-new proteins are synthesised
-DNA is replicated to produce chromosomes that consist of two sister chromatids joined by a centromere
what is the spindle essentially a name for?
collective term for all spindle fibres together
before mitosis, what do chromosomes contain?
2 genetically identical sister chromatids- this is due to DNA replication at interphase
what happens during prophase? (3)
-chromosome condense (coil to shorten and thicken) and become visible
-nuclear membrane begins to break down
-spindle fibres begin to form
what happens during metaphase? (4)
-nuclear membrane fully breaks down
-spindle fibres fully form
-chromosomes line up individually at the equator of the cell
-spindle fibres attach to the chromosomes at the centromere
what happens during anaphase? (3)
-centromeres divide
-sister chromatids of each chromosome are pulled apart
-spindle fibres contracting is what allows this to happen
-they are pulled to opposite poles of the cell
what happens during telophase? (5)
-spindle breaks down
-nuclear membrane reforms
-chromosomes decondense (uncoil)
-cell membrane forms down centre of cell (cytokinesis)
-two identical daughter cells produced
what is cytokinesis?
when the cell membrane grows down the centre of the cell, to separate the parent cell into 2 identical daughter cells
what are the 3 importance’s of mitosis?
- GROWTH
- REPAIR
- REPRODUCTION
what is the mitotic index?
the ratio between the number of cells in a population undergoing mitosis to the number of cells.
higher mitotic index= greater number of cells dividing
what is the equation for working out mitotic index?
number of cells actively dividing cells in field of view // total number of cells in field of view
to get it as a percentage x100
