10.1 Study Guide Flashcards
What is the order and events of cell cycle stages (G1, S, G2, M, G0, interphase)?
Interphase: G1, G0, S, G2
Mitosis occurs after Interphase.
Interphase: Where the cell spends most of its time growing, replicating DNA, and preparing to divide.
G1: The cell increases in size and prepares to replicate its DNA.
G0: The cell can differentiate or go into a “resting” state when resources are insufficient to grow and divide.
S: The cell replicates its DNA. At the end of this phase, the cell has two complete sets of chromosomes.
G2: The cell continues to grow and prepares for division.
Mitosis: The stages where the cell divides into two identical daughter cells.
Examples and roles stimulatory proteins (growth factors, cyclins, cdks) and inhibitory proteins (p53).
Stimulatory proteins: Proteins that cause the cell to pass itks progress through the cell cycle at critical points.
Growth factors: Proteins released by body cells to stimulate other nearby cells to divide or differentiate.
Cyclins: Proteins that bind to CDKs to form complexes/kinases that phosphorylate target proteins and enzymes to turn various types of cellular processes/reactions/gene expressions on and off.
CDKs: CDKs are enzymes that bind with cyclins in order to phosphylate DNA replication enzymes to activate S phase.
Inhibitory Proteins: Proteins that cause the cell to stop its progress through the cell cycle at critical points.
P53: An inhibitory protein that stops cell progression if DNA is damaged, until the damage is repaired. If the damage can’t be fixed, then p53 can initiate cell death, or apoptosis.
What are proto-oncogenes and tumor suppressor genes? What are some examples of them?
Proto-oncogenes: Code for stimulating proteins. Become “oncogenes” when mutated. If one switched permanently “ON”, it can cause cancer. Ex: Cyclins and growth factors
Tumor suppressor genes: Code for inhibitory proteins (degrade or prevent formation of cdk/cycling complexes). If both of your versions are switched “OFF”, it can cause cancer. Ex: p53, since gene p53 stops division if DNA mutates/is damaged. All cancers have to shut down p53 activity.
Compare and contrast any of the concepts/terms above as applicable.
All of the stages of interphase prepare the cell for division, while mitosis is the actual process of division. G1 and G2 both involve growth, but G2 grows the cell after the DNA has been copied into two complete set of chromosomes. Stimulatory proteins stimulate the cell’s movement through the cell cycle, while inhibitory proteins inhibit the cell’s movement through the cell cycle. Proto-oncogenes code for stimulatory proteins, and tumor suppressor proteins code for inhibitory proteins. When mutated, both of these proteins can cause uncontrolled cell division, causing cancer.
Explain why mutations in proto- oncogenes and tumor suppressor genes lead to cancer.
Mutations in proto-oncogenes can cause them to turn into oncogenes. Oncogenes increase stimulation of the cell cycle, which can lead to uncontrolled cell division. This leads to cancer.
Mutated tumor suppressor genes can cause a loss of inhibition to the cell cycle. This can lead to uncontrolled cell division, which leads to cancer. One mutated tumor suppressor gene allele has no impact on the cell cycle because these mutations are recessive. Two mutated tumor suppressor alleles results in a loss of function for the cell cycle.
