Mitosis/Cell Division Flashcards
How long is a eukaryotic cell cycle?
24 hours
Interphase - 23hrs
Mitosis - 1 hour
What is G1?
Start checkpoint for growth and repair of cells
What is s phase?
Duplication of genetic information
What is G2?
M checkpoint before entering mitosis
Describe cyclin-dependent kinase (Cdk)
G1/S-cyclin levels inc causing cyclin to bind to Cdk, becomes activated and phosphorylates other proteins
What happens if inhibitory signals are present in cyclin-dependent kinase?
If present, may decrease levels of cyclins
Mitosis is prepared using cohesins and codensins.
What are cohesins?
Proteins that hold sister chromatids together
What are codensins?
Cause chromosomes to condense (during late prophase/early metaphase) - Chromosome only begin to condense in prophase, become condensed in metaphase
How do you ensure each cell receives one copy of chromosomes?
Keep replicated chromosomes together until organised
Use cytoskeleton to organise movement of chromosomes
Describe the role of microtubules in mitosis
Attach to kinetochores found at centromere which holds sister chromatids together. Also form spindle fibres that move chromatids around
How is the mitotic spindle formed?
Centrosome duplicates during interphase, each centrosome migrates during prophase to either side of nucleus to form spindle poles
What is a centrosome?
Microtubule organising centre (contains pair of centrioles in animals)
Describe the separation of sister chromatids during anaphase
Shortening of kinetochore microtubules cause spindle fibres to move apart
