Cell division and cycle Mitosis Flashcards
1
Q
Cell division
A
- Enables continuity of life cell cycle is essential so that organisms can grow and reproduce
2
Q
Phase G0
A
- Resting phase where the growth slows down e.g. muscle cells rarely divide
3
Q
Overview of cell cycle
A
- M phase which has mitosis and cell division
- G1 Phase
- S Phase
- G2 Phase
4
Q
Cell cycle control system
A
- Internal control to ensure the proper progression of the cell cycle and that key steps occur in the right sequence
5
Q
Checkpoints during Mitosis
A
- Pauses the cycle at 3 main transition points G1/S,G2/M and metaphase to anaphase transition
- Doesn’t trigger the next step until cycle properly finishes
6
Q
Checkpoint progression
A
- Dependant on critically activated cyclin dependant protien kinase (Cdks)
- Cdks must bind to regulatory protein cyclin to activate
- Cdks must be in a particular phosphorylation state
- Activated Cdks phosphorylate proteins for checkpoint transition (initiate DNA replication)
7
Q
Cyclin-Cdk complex
A
- Enables the triggering of diffrent steps in the cycle
- Passage through checkpoints of cells are irriversible
- Cyclin destroyed after not needed
- Cdks not destroyed just deactivated
8
Q
G1 Phase
A
- Metabolic activity cell growth and repair growing in mass before division
- Checks for cell size, nutrients and DNA integrity
- Can progress to S phase
- delay progress to S phase due to damage DNA
- Exit to phase 0 or program cell death
9
Q
S phase
A
- DNA replication occours so high regulation
- Once entered into S phase S-Cdks activate helicase form replication fork
- Sister chromatid connected by cohesion
- Centromere duplicate
10
Q
Centrosome
A
- Cellular structure that controls location and number of microtubles
- Consists of 2 centrioles
- Organises microtubules to make cytoskeleton
- Organises microtubles into spindle fibres
11
Q
G2 Phase
A
- Rapid cell growth and protein synthesis
- Check unreplicated and damaged DNA
- Checkpoint pass the proteins for early mitosis activated
- Incomplete replication arrests cycle
12
Q
M Phase Overview
A
- Prophase - condese chromasome start 2 pole form no more transcripton
- Prometaphase - nuclear envelope breakdown chromasome attach spindle microtuble
- Metaphase - Chromasomes aligned at the equator, M checkpoint controlls alignment
- Anaphase - Sister chromatids seperate move to poles
- Telophase - Reform nuclear envelope
- Cytokinesis - Seperate 2 daughter cells
13
Q
Apoptosis
A
- Programmed cell death induced by external and internal stimuli
- Remove cells during embryonic development
- Cells no longer needed
- Cells with severe DNA damage
- Cells with viral infections
- Necrosis acute injury causing rupture of cell
14
Q
Intrinsic apoptosis activation
A
- Alter permeability of mitochondrial outer membrane release of cytochrome C from intermembrane space into cytosol
- Cytostolic cytochrome C causes hydrolysis of inactive procaspase to active caspase
15
Q
External apoptosis
A
- Exposure of death signal from diffrent cell (fas ligand or T killer cell)
- Death receptors on surface
- Fas ligand recptor binds and recruits adaptor protein
- procaspase molecules and hydrolyse them to active caspase
