Cell Cycle and Mitosis

what are the 3 main phases of cell division in eukaryotic cells?

• interphase

• mitosis

• cytokinesis

what causes the length of each part of the cell division cycle from varying?

• environmental conditions

• cell type

• the organism

what are the 3 phases involved in interphase?

• G1 phase

• S phase

• G2 phase

what happens in the G1 phase?

• cells produce RNA, enzymes and other proteins

• cells receive division signal

what thing gives the signal for cells to divide?

cyclins

what happens in the S phase?

• the synthesis of new DNA

• the DNA replicates, with each chromosome containing two identical sister chromatids

what is the G2 phase?

• newly synthesised DNA checked for errors

• tubulin protein made

what is the definition of mitosis?

a type of nuclear division where two genetically identical daughter nuclei are produced

what are the 4 phases of mitosis? (PMAT)

• Prophase

• Metaphase

• Anaphase

• Telophase

what three things is mitosis fundamental for?

• growth of multicellular organisms

• replacement of cells and repair of tissues

• asexual reproduction

what are centrosomes?

organelles that become visible during mitosis in order to help pair up and move chromosomes

what do centrosomes contain which attach to spindle fibres?

2 centrioles

what happens in the prophase?

• chromatin condenses forming chromosomes, joined together at the centrometre

• centromeres move to opposite poles, spindle fibres emerge from them

• nuclear envelope breaks down into vesicles and nucleolus disappears

what happens in the metaphase?

• chromosomes line up at the equator of the spindles

• spindle fibres attach to the centrometres

what happens in the anaphase?

• sister chromatids separate at the centrometre

• spindle fibres shorten to pull the separated chromatids to opposite sides of the cell

what happens in the telophase?

• chromosomes arrived at opposite poles and decondense

• nuclear enveloped reforms around each set of chromosomes

• spindle fibres break down

what is cytokinesis?

the physical separation of the parent cell into two genetically identical daughter cells

what are the checkpoints for ensuring DNA is correct?

• G1 checkpoint

• S phase checkpoint

• G2 checkpoint

• Metaphase checkpoint

what happens in the G1 checkpoint of DNA?

checks chromosomes for damage

what happens in the S phase checkpoint?

ensures all DNA has been successfully replicated

what happens in the G2 checkpoint?

checks replicated DNA for any additional damage

what happens at the metaphase checkpoint?

confirms chromosomes are correctly attached to spindle fibres