cell division-mitosis Flashcards
what are the two main phases in the cell cycle?
m phase(mitotic phase) and interphase.
what are the three phases during interphase in the cell cycle?
G1 phase, S (synthesis) phase and G2 phase
what occurs during the G1 phase? (3 points)
-organelles replicate
-high levels of transcription and translation occurs as replicating organelles requires a great deal of proteins
-cell size increases
what occurs during the S phase? (2 points)
-chromosomes are replicated
-DNA synthesis
what occurs during the G2 phase? (4 points)
-energy stores replaced
-transcription/ translation
-chromosome repair if damaged
-cell size increases
what are the two phases that occur during the mitotic phase?
mitosis when chromosomes separate into two nuclei and cytokinesis when the cell divides into two.
what is the G0 phase?
when a cell leaves the cell cycle. This can be permanent or temporary.
what are the three reasons to why cells enter the G0 phase?
-a fully differentiated cell will carry out its function indefinitely and not enter the cell cycle (e.g adult neurone)
-senescent cells where the DNA is damaged and it is no longer viable. At this stage the cell enter G0 permanently.
-cells in G0 temporarily (e.g B memory cells) which must be triggered to re-enter the cell cycle.
what happens when a cell doesn’t pass a checkpoint?
it will enter G0
where are the three checkpoints?
-G1 checkpoint before entering the S phase, it is checked for the correct size growth and DNA damage.
-end of G2, before the mitotic phase, it is checked for DNA damage and cell size growth.
-end of mitotic phase. This is also called the metaphase checkpoint or spindle checkpoint. This checks that the chromosomes are assembled correctly on the mitotic spindle. If the cell passes this checkpoint, cytokinesis occurs.
what is a diploid cell?
a cell that contains two copies of each chromosome.
what occurs during interphase in the cell cycle(4 points)?
-energy stores increase
-cell size growth
-organelles replicated
-DNA copied
what occurs during the M (mitotic) phase?(2 points)
nucleus divides (mitosis) and cell divides (cytokinesis)
what are the four stages in mitosis?
prophase, metaphase, anaphase and telophase
what occurs during prophase in mitosis?
the chromosomes condense and become visible in the nucleus. At this stage the chromosomes consist of two sister chromatids joined at the centromere. The nucleolus disappears and the nuclear membrane starts to break down. A pair of centrioles move to opposite poles of the cell. Proteins begin to form spindle fibres which attach to the centromere of each chromosome. The spindle fibres move the chromosomes towards the equator of the cell.
