2.1.6 Cell division, cell diversity and cellular organisation Flashcards
What is the cell cycle?
The cell cycle is a series of events during which the cell duplicates its contents and splits into two identical daughter cells.
What are the key stages of the cell cycle?
Interphase (G1 phase, S phase, G2 phase)
Mitosis (nuclear division)
Cytokinesis (cell division)
What are the purposes of checkpoints within the cell cycle?
To prevent uncontrolled division which would lead to tumours.
To detect and repair damage to DNA.
To make sure DNA has only been replicated once.
To make sure the cell cycle only progresses in one direction.
What happens in the cell during the G1 phase?
cells grow and increase in size
Transcription of genes to make RNA.
Organelles duplicate.
Biosynthesis, e.g. protein synthesis occurs to make enzymes needed for DNA replication in the S phase.
What happens in the cell during the G0 phase?
Cell may undergo apoptosis (programmed cell death)
Cell may undergo differentiation.
Cell may enter senescence (where the cell can no longer divide)
What happens in the cell during the S phase?
DNA replicates
Chromosomes duplicate so that each now contains a pair of identical sister chromatids.
What happens in the cell during the G2 phase?
Cell grows
What happens in the cell during the M phase?
Cell growth stops
Nuclear division/ mitosis occurs (stages of mitosis: prophase, metaphase, anaphase, telophase)
Cytokinesis occurs
The M phase is rapid, why is this beneficial to the cell?
The DNA base pairs are exposed.
So they are more susceptible to mutagenic agents.
The speed of this stage is beneficial as it reduces the chances of spontaneous mutations happening.
What does the G1 checkpoint do/ check for?
It ensures that the cell is ready to enter the S phase and begin DNA replication.
Checks for:
- cell size
- nutrients
- growth factors
- DNA damage
What does the G2 checkpoint do/ check for?
It ensures that the cell is ready for mitosis.
Checks for:
- cell size
- DNA replication
- DNA damage
