Week 9 - Cell Cycle and Cell Division Flashcards
When does cell division occur
- development
- healthy homeostasis
- Wound repair
- Mis-regulation leads to cancer
Where has the highest turnover rate of cells in the body
oral epithelium
probably due to an evolutionary response to the continual injury suffered by the oral lining epithelia.
What is tumorgenesis
Tumorigenesis is the gain of malignant properties in normal cells including fast proliferation (increases the rate of cell division by breaking the proteins which regulate the speed of cell division normally)
How many chromosome pairs are there in humans
23
How many individual chromosomes do humans have
46
What are the 2 main phases of the cell cycle
- Interphase
- Mitotic phase
What is the interphase
takes up 90% of a cells life and is where the cell is undergoing its natural function and is not dividing
What is the mitotic phase
includes both mitosis and cytokinesis (division of organelles)
What are the 4 subphases in interphase
G1 phase
G0 phase
S phase
G2 phase
What occurs in G1 phase
when the cell is ‘doing its job’ and there’s no cell division
What occurs in G0 phase
A subclass of G1 which prevents cell division from occuring
What occurs in S phase
When the cell is copying its chromosomes
What occurs in G2 phase
When the cell is growing and preparing for cell division
What are the intracellular signaling proteins which control the cell cycle checkpoints
cyclins
cyclin dependent kinases
What are kinases
Enzymatic proteins which activate or inactivate other proteins by phosphorylating them (adding a phosphate group to something)
What are cyclins
A family of proteins who’s concentration varies in a cyclical fashion during the cell cycle. Ultimately these proteins control the progression of a cell through the cell cycle by activating cyclin-dependent kinases
What are cyclin dependent kinases
Acts as the ‘go-ahead’ signal at checkpoints. They are kinases that require the presence of cyclins to be active.
What are the checkpoints in the cell cycle
G1 - checkpoint
G2 - checkpoint
M - checkpoint
What does a cell need to pass the G1 checkpoint
- sufficient number of organelles
- growth factors activation
What does a cell need to pass the G2 checkpoint
- completely replicated genome
- no DNA damage
- large cell volume
What does a cell need to pass the M checkpoint
equal distribution of chromosomes between new daughter cells
What is the most important cell cycle checkpoint
G1 checkpoint
What is the function of the G1 checkpoint
if the cell does not receive a go ahead signal they will not undergo cell division and will enter G0 (state of no division)
