Cytoskeleton + Cell Cycle Flashcards
What does the cytoskeleton provide
Mechanical support and shape to cells
What are microtubules composed of
Soluble globular proteins called tublin
Where do microtubules radiate from
They radiate from the MTOC or centrosome
What is the remodelling of the cytoskeleton required for
Cell division
What results in the breakdown and formation of microtubules
Polymerisation and depolarisation of tublin
When do microtubules activate
During cell division
What does the cell cycle consist of
Interphase and mitotic phase (mitotic being cytokinesis and mitosis)
What does mitosis consist of
- Prophase
- Metaphase
- Anaphase
- Telophase
What is the interphase
Interphase consists of growth and DNA synthesis - includes:
- G1 - growth phase
- S phase - DNA is replicated
- G2 - further growth phase
What does prophase consist of
- DNA condenses into chromosomes - forms two sister chromatids
- Spindle microtubules extent from MTOC by polymerisation and attaches by kinetochores in centromere region
What occurs during metaphase
Chromosomes are aligned at metaphase plate (equator of spindle)
What occurs during anaphase
- Depolymerisation shortens microtubules
- sister chromatids are separated
- chromosomes pulled to opposite poles
What occurs at telophase
Chromosomes decondense and nuclear membranes form around them
What occurs at cytokinesis
Cytokinesis occurs and forms two daughter cells
What proteins accumulate during the cell cycle
Cyclin proteins accumulate and involved in regulating the cell cycle
What does the metaphase checkpoint control
Controls progression of metaphase to anaphase and is halted unti chromosomes are aligned correctly on metaphase plate
What occurs at the G1 checkpoint
Retinoblastoma protein acts as a tumour suppressor by inhibiting transcription of genes.
What occurs at G2 checkpoint
Any damage to the DNA is assessed
What does damage to the DNA trigger
Triggers activation of p53 which is protein that stimulates DNA repair, arrest of cell cycle, and cell death
What occurs at the metaphase checkpoint
Metaphase to anaphase progression halted until chromosomes aligned correctly on metaphase plate
What inhibits the retinoblastoma protein
Phosphorylation by G1 cyclin-CDK
What could be a result of degenerative disease
Uncontrolled reduction in the rate of the cell cycle
What could result in a tumour formation
An uncontrolled increase in the rate of the cell cycle
What is the proto-oncogene
Gene involved in the control of cell growth or division which can mutate to form a tumour-promoting oncogene
What are involve in regulating the cell cycle
Cyclin proteins that accumulate during cell growth
