Cell Replication Flashcards
What is the cell cycle?
An orderly sequence of events in which the cell duplicates its contents and divides in two
What stages of the cell cycle make up interphase?
G1 + S + G2
What factors do different rates of mitosis depend on?
- How complex the system is
- The need for renewal
- Age
- Tumour = out of sync replication
- State of differentiation as some cells never divide
Which cells never divide?
Neurons and cardiac myocytes
What does pre-mature, abnormal mitosis result in?
Cell death
Why is mitosis the most vulnerable period of the cell cycle?
DNA damage cannot be repaired, gene transcription is silenced, cell metabolism is low, cells are killed more easily
What is G0?
The quiescent phase
What state are the cells in when they are in G0?
The cells are not dormant, but non-dividing
What does the centrosome consist of?
Two centrioles at 90 degrees to one another
What is a centriole?
Barrels of 9 triplet microtubules which form the mitotic spindle
Where do the microtubules grow from on the centrosome?
Microtubules grow from the nucleating site on the centrosome
Microtubules are polymers of what?
Alpha and beta tubulin dimers
What is a kinetochore?
Protein complexes that assemble at the centromere of a chromosome and function to connect the chromosome to the microtubules during anaphase
In what phase of mitosis does the spindle attach to the kinetochore?
During metaphase
What happens to the microtubules during anaphase?
They get shorter as they pull chromosomes apart
In which phase d the spindle microtubules start to form?
Prophase
What occurs in the G1 phase of the cell cycle?
The cell makes mRNA and proteins in preparation for the next steps
What is aneuploidy?
An abnormal number of chromosomes
What is meant by syntelic attachment of the spindle?
When both kinetochores attach to spindle from one spindle pole, so the whole chromosome is pulled to one pole
What is meant by merotelic attachment?
When spindle from two poles attach to one kinetochore
What occurs during the S phase?
The synthesis phase - organelle replication and protein synthesis
What happens during the G2 phase?
Period of rapid cell growth in preparation for mitosis
What happens to cohesin during anaphase?
Cohesin breaks down
What occurs during the telophase?
The daughter chromosomes arrive at the spindle and nuclear envelopes reassemble at each pore