1.5 Protein Control Of Cell Division Flashcards
Describe the role of the cytoskeleton and describe how it can be remodelled during cell division
Gives cell support and shape
Polymerisation and depolymerisation of Tubulin
Name the different phases of a normal cell cycle and state what occurs in each.
M phase divides by mitosis
G1 growth
S (synthesis) DNA replicates
G2 further growth
Describe the movements of the chromosomes during mitosis
Prophase: DNA condenses into chromosomes
Metaphase: chromosomes move to metaphase plate/equator and attach to spindle by kinetochores
Anaphase: sister chromatids separated and chromosomes move towards opposite poles
Telophase: chromosomes start to decondense
Describe the G1 checkpoint
Cyclins accumulate
CDKs phosphorylate Rb
Rb inhibited so genes transcribed
To allow proteins needed for S to be synthesised
Describe the G2 and metaphase checkpoints.
G2 checkpoint DNA replication/damage assessed Go-ahead allows progress to M phase Metaphase checkpoint Assess chromosome attachment to spindle Go-ahead allows mitosis to complete
Explain why a tumour may be formed.
A proto-oncogene mutates to form a tumour-promoting oncogene.
Explain how apoptosis can be triggered
By external death signals/lymphocytes
Internal death signals/activation of p53
Lack of growth factors
What is the cytoskeleton?
The cytoskeleton gives mechanical support and shapes to cells.
What does the cytoskeleton consist of?
The cytoskeleton consists of different protein structures including microtubules, which are found in all eukaryotic cells.
What are microtubules?
Microtubules are hollow cylinders, composed of the protein tubulin, which radiate from the microtubule organisation organising centre (MTOC) or centrosome.
Microtubles control the movement of membrane bound organelles and chromosomes.
What does cell division require?
Cell division requires remodelling of the cytoskeleton.
What is anaphase?
Phase in which spindle microtubules shorten by depolymerisation, sister chromatids are separated and the chromosomes are pulled to opposite poles.
What is apoptosis?
Programmed cell death triggers by cell death signals that can be external or internal.
What is caspase cascade?
Protease enzymes involved in a series of reactions (a cascade) that destroy a cell.
What is a cell cycle?
Four-stage process in which the cell increases in a size (G1 stage), copies its DNA (S stage), prepares to divide (G2 stage) and divides by mitosis (M stage).
