2.1.6 Cell cycle - The cell cycle Flashcards
Define Cell cycle
The cell cycle is a highly ordered sequence of events that takes place in a cell, resulting in division of the cell, and the formation of two genetically identical daughter cells.
What happens at the interphase?
- DNA is replicated and checked for errors in the nucleus
- Protein synthesis occurs in the cytoplasm
- Mitochondria grow and divide, increasing in number in the cytoplasm
- Chloroplasts grow and divide in plants and algal cell cytoplasm, increasing in number in the cytoplasm
- The normal metabolic processes of cells occur.
How many stages are there in the interphase stage and what is their role?
G1 – The first growth phase: Proteins from which organelles are synthesised are produced and organelles replicate. The cell increases in size.
S – Synthesis phase: DNA is replicated in the nucleus.
G2 – The second growth phase: The cell continues to increase in size, energy stores are increased and the duplicated DNA is checked for errors.
What are the functions of mitosis?
Mitosis is needed for the growth of multicellular organisms and for repairing damaged tissues. It is also a method of asexual reproduction for some plants, animals and fungi.
What are the stages of mitosis?
Interphase: it is when cells grow and replicate their DNA ready for division.
Prophase (the before stage)
Metaphase (adjacent or between stage)
Anaphase (back/backward stage)
Telophase (end/result/completion stage)
Cytokinesis: the cytoplasm divides and two cells are produced.
PMAT
What is G0?
Is the phase when the cell leaves the cycle, either temporarily or permanently.
Why is the cell controlled? Why are there checkpoints?
To ensure a cell only divides when it has grown to the right size, the replicated DNA is error-free (or is repaired) and the chromosomes are in their correct positions during mitosis. It is to ensure the fidelity of cell division – that two identical daughter cells are created from the parent cell. To avoid mutation.
Define checkpoints
Are the control mechanisms of the cell cycle. They monitor and verify whether the processes at each phase of the cell cycle have been accurately completed before the cell is allowed to progress into the next phase.
What are the 3 checkpoints during the cell cycle and what do they check?
G1 checkpoint – is the cell big enough and the environment stable? G2 checkpoint – has DNA replicated, is the cell big enough and the environment suitable? Spindle assembly (metaphase) checkpoint – are chromosomes aligned on the spindle?
