Topic 1.6 - Cell division Flashcards
What is the cell cycle ?
The cell cycle is an ordered set of events that culminates in cell division
What is the longest phase in the cycle ?
Interphase - An active phase of the cell cycle where many metabolic reactions occur
* Consists of G1, S and G2 stages
What is the shortest phase in the cell cycle ?
M phase - The period of a cell cycle in which the cell and contents divide
* Consists of mitosis (P, M, A, T) and cytokinesis
What happens during interphase ?
Normal metabolism cannot occur during M phase, so key events must occur during interphase to prepare for division:
* DNA replication (during S phase)
* Organelle duplication
* Cell growth
* Transcription / translation
* Obtaining nutrients
* Respiration (cellular)
Supercoiling happens during mitosis, what does it consist of ?
During mitosis, chromatin condenses via supercoiling to
become tightly packed chromosomes
* Due to replication (S phase), chromosomes consist of
identical sister chromatids (joined at a centromere)
What is mitosis ?
Mitosis is the division of a diploid nucleus
into two genetically identical diploid nuclei
What important processes require mitosis ?
- Tissue repair
- Organism growth
- Asexual reproduction
- Development of embryos
What is cytokinesis ?
Cytokinesis is the process of cytoplasm division, whereby a cell splits in two
* It occurs concurrently with telophase and differs in plants and animals
Cytokinesis is different in animal and plant cells, how does it happen in animal cells ?
Microtubules form a concentric ring and
contract towards the centre (centripetal)
Cytokinesis is different in animal and plant cells, how does it happen in plant cells ?
Vesicles form at the cell centre and fuse
outwards to form a cell plate (centrifugal)
What is the mitotic index ?
The mitotic index is a measure of the proliferative
status of a cell population (i.e. number of dividing cells)
When is the mitotic index elevated ?
The mitotic index will be elevated during growth and
repair processes and acts as a prognostic tool for cancer
How do we calculate the mitotic index ?
Mitotic Index = cells in mitosis / total number of cells
