What are the phases of the cell cycle?
- G1 Gap Phase (growth)
- S Phase (Synthesis - where the DNA Replicates)
- G2 Gap Phase (Finnish growth and make sure things are intact for mitosis)
- M Phase - (Mitosis - Chromosomal separation and Cytokinesis
What is G0 (G “not)?
Also known as (quiescent) – occurs if the cells are not actively dividing and exit the cell cycle. They will not re-enter the cell cycle. A phase of cell division
What are the different stages of mitosis (G2)?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
- Cytkinesis
What occurs during prophase?
Chromosomes condense. Centrosomes radiate microtubules and migrates to opposite poles.
What occurs during prometaphase?
Microtubules of the mitotic spindle attach to chromosomes at the centromere. The nuclear envelope starts to break down.
Kinetochore is part of the centromere and is a protein that helps the spindle attach
What occurs during metaphase?
Chromosomes align in the center
What occurs during anaphase?
Sister chromatids (which become individual chromosomes when the centromere splits) separate and travel to opposite poles
What occurs during telophase?
Nuclear envelope re-forms and chromosomes decondense. You end with a cell that has two nuclei
What occurs during cytokinesis?
Cytokinesis (occurs with animals) Creates a contractile ring that divides the cell.
Cytokinesis (Plant): Instead of a contractile ring – they grow a cell wall and they stay attached.
What occurs during Gametogenesis?
Gametogenesis is the production of gametes from haploid precursor cells.
How is the function of an enzyme controlled?
Through proteins and their following roles:
- Presence of absence
- Modification such as phosphorylation
- Turnover or half-life
- Co-regulators
What is the kinase (CDK)?
The kinase is a protein that are always present during the cell cycle (car in the driveway ready to use). I will either be used for (2) modification such as phosphorylation or (4) co-regulation
—-> We know it is not (1) because it is always present, and we know it’s not (2) because if it’s always present it won’t have a fast turnover rate.
What is the cyclin?
There is an enzyme called cyclin (driver) -> These activate the “complex” (combo of kinase and cyclin)
–> it will only be there for a short period of time.
It will be regulated by (1) It’s presence or absence and since it will only be around a short time we know it will be quickly degraded (3)
What due the cyclin and kinase perform together?
Once these two components are together, the complex is now considered active and can form a function. It will perform a function on another protein that will result in its phosphorylation. (2)
—> Now that the driver is in a car something can be done.
What happens after the complex?
You then get a new driver (cyclin) but with the same car (CDK), but now for a new target (phosphorylation)
Define cancer
Activating or inactivating a gene thats performing an important function of the cell cycle. They are a proliferation gone wrong. Problems in cell cycle regulation
What are the different ways a cell causes cancer?
- Oncogene: Cancer-causing gene when inappropriately turned on.
- Proto-oncogenes: Normal genes important in cell division that have the portential to become cancerous if mutated. When mutated they become oncogenes. EXP. Cyclins are there to promote cell division (protooncogenes) OR CDK’s - Proto-oncogenes as their normal function is to promote cell division/
- Tumor suppressors: Genes that encode proteins whose normal activities inhibit cell division. EXP. P53 is a protein to inhibit cell cycling so this is essentially a tumor suppressor.
What is P53?
A tumor suppressant gene that is activated when there is DNA damage
