Cell cycle regulation (1)

Question 1

What is the definition of cell proliferation?

Answer 1

• An increase in the number of cells; as a result of cell growth and cell division
• In other words cells need to grow and divide to make new cells

Question 2

describe cell signals

Answer 2

• Can come outside of the cell e.g. growth factor or an extracellular matrix molecule etc
• These will bind to a cell surface receptor and set in motion a signalling pathway which will end up in the nucleus where it will affect gene regulation and allowing the cells to proliferate
• If there is too many cells, the removal of these growth factors will stop cell division, also death factors can bind if there are too many cells

Question 3

define growth factor

Answer 3

Polypeptides that control animal cell growth a differentiation. Usually produced near where they act. Can be stored and released by ECM

Question 4

define transcription factor

Answer 4

A protein that regulates the activity of RNA polymerase

Question 5

define cell signalling

Answer 5

phosphorylation of residues

Question 6

define mitosis

Answer 6

is the division of the nucleus of a eukaryote cell, involving condensation of the DNA into visible chromosomes, and separation of the duplicated chromosomes to form two identical sets

Question 7

Give an overview of mitosis

Answer 7

• chromosome condensation
• formation of mitotic spindle
• attachment of chromosomes to spindle
• sister chromatids separate
• move to opposite poles of spindle
• formation of new nuclei

Question 8

describe cell cycle controllers

Answer 8

• family of protein kinases
• cyclin dependent kinases (Cdks)
• activity rises and falls
• cyclical changes in phosphorylation - intracellular proteins
• Inititate and control major events of cell cycle - DNA replication mitosis and cytokinesis

Question 9

Describe cyclin dependent kinase

Answer 9

• Cdk controlled by cyclins
• Cdk needs cyclins for protein kinase activity
• Cyclins undergo cycle of synthesis during cell cycle

Question 10

describe the 4 classes of cyclins

Answer 10

• G1/S - cyclins bind at end G1- commit cell to DNA replication
• S-cyclins bind Cdks during S phase initiate DNA replication
• M-cyclins promote events of mitosis
• G1 cyclins promote passage through restriction point

Question 11

Cell cycle control systems (points to remember)

Answer 11

• cyclin does not simply activate the Cdk but directs it
• Different proteins phosphorylated
• Accessibility