Cellular Adaptations Flashcards
What 3 things affect cell population
Rate of cell proliferation
Rate of cell differentiation
Rate of deal death by apoptosis
What are 2 types of causes of cell proliferation
How are they related?
Physiological
Pathological
Excessive physiological can become pathological
In regards to the cell cycle , what are 2 ways increased tissue growth occurs?
- Shortening of cell cycle
- Conversion of quiescent cells to proliferating cells
How many key checkpoints are there in the cell cycle?
What are they? Which is the most critical?
Out of the 3, which is most commonly altered in cancer cells
3
- G1/ S
- G2/M
- Restriction Point (Towards end of G1), Most critical
In cancer, Restriction point
Compare the G1/ S and G2/ M checkpoints
G1/ S: Checks for DNA damage before replication
G2/ M: Checks for DNA damage after replication
What happens the the majority of cells that pass the Restriction point of cell cycle?
What happens if the checkpoint is activated?
Most will complete the cell cycle
If the checkpoint is activated, protein p53 arrests the cell cycle and triggers DNA repair mechanisms OR apoptosis
Which protein is called the guardian of the genome
P53
What proteins and enzymes control the cell cycle?
How are they linked?
Cyclins and Cyclin Dependent Kinases (CDKs)
CDKs become activated by binding to cyclins
How do ACTIVATED CDKs control the cell cycle?
Drive cell cycle by phosphorylation of proteins, that are needed for cell cycle to progress to next stage
What molecules regulate the activity of Cyclin-CDK complexes?
How do growth factors affect Cyclins and CDKs
CDK inhibitors
Growth factors either;
- Stimulate cyclin production
- Inhibit CDK Inhibitor production
What is the role of Retinoblastoma Protein?
Which cyclin/ CDK complex affects it and how?
- Prevents DNA Replication
- Inactivated by phosphorylation by Cyclin D/ CDK 4 complex
Name 3 molecules that stimulate cell proliferation
Name 2 that inhibit cell proliferation
- Oncogenes
- Cyclins/ CDK complex
- Growth factors
- CDK inhibitors
- Tumour suppressor genes
Define Cellular Adaptation
The reversible state between normal under stressed cell and injured over stressed cell
What are 4 ways cells can adapt?
- Hyperplasia
- Hypertrophy
- Atrophy
- Metalasia
How can Hyperplasia lead to Dysplasia?
If stimulus is not removed