2.1.6 Cell division, cell diversity and cellular organisation Flashcards
What is the cell cycle?
carefully regulated sequence of events btwn one cell division and the next
phases of cell cycle
interphase, mitosis, cytokinesis
what could influence the length of the cell cycle?
- environmental conditions
- cell type
- organism
How is movement from one phase to another done?
triggered by chermical signals called cyclins
what happens during interphase?
cell increases in mass and size and carries out its normal cellular functions
Phases of interphase?
G1 phase
S phase
G2 phase
What happens in the G1 phase?
Cells make the RNA, enzymes and other proteins required for growth
what happens in the S phase
DNA in the nucleus replicates (resulting in each chromosome consisting of two identical sister chromatids)
What happens in the G2 phase?
cell continues to grow and the new DNA that has been synthesised is checked and any errors are usually repaired
What happens after interphase?
nuclear division (mitosis)
What won’t happen in mitosis
cell growth
What happens after mitosis?
cytokinesis
What happens in cytokinesis
Once the nucleus has divided into two genetically identical nuclei, the whole cell divides and one nucleus moves into each cell to create two genetically identical daughter cells
cytokinesis in animal cells?
cytokinesis involves constriction of the cytoplasm between the two nuclei
Cytokinesis in plant cells?
new cell wall formed
How is the cell cycle regulated?
several checkpoints throughout the cell cycle where the genetic information contained within the replicated DNA is checked for any possible errors
What if an error is present in DNA?
When possible enzymes will repair the error but in some cases the cell may destroy itself to prevent passing on harmful mutations
checkpoint during G1 phase?
chromosomes are checked for damage. If damage is detected then the cell does not advance into the S phase until repairs have been made
checkpoint during S phase
chromosomes are checked to ensure they have been replicated. If all the chromosomes haven’t been successfully replicated then the cell cycle stops
Checpoint during G2 phase
an additional check for DNA damage occurs after the DNA has been replicated. The cell cycle will be delayed until any necessary repairs are made
Checkpoint during metaphase?
the final check determines whether the chromosomes are correctly attached to the spindle fibres prior to anaphase
What is mitosis?
process of nuclear division by which two genetically identical daughter nuclei are produced that are also genetically identical to the parent cell nucleus
Steps of prophase? (5)
- chromosomes condense to be visible when strained
- chromosomes have 2 sister chromatids (identical) that are joined together at the centromere
