The Cell Cycle Flashcards
What is the cell cycle?
A series of phases that a cell goes through as it grows, replicates, and divides
What occurs at each phase of the cell cycle?
(Hint - 4 phases)
G1: Growing and making more proteins/organelles in preparation for division
S: DNA Synthesis - DNA replicated and split into two daughter cells (chromosomes)
G2: Rapid growth and protein/organelle synthesis
M: Mitosis (Cell division) - chromosomes line up in center and split into two daughter cells
What are checkpoints and why are they important?
Checkpoints ensure cells are functioning properly in order to move onto the next phase/reproduce
Which phases of the cell cycle have checkpoints associated with them?
G1, G2, and M phases
What are some of the things that cells look for at each checkpoint?
Size: Is the cell large enough?
Nutrients: Are there enough energy reserves?
Molecular signals: Are there positive cues from other cells?
DNA Integrity: Is the cell damaged?
Why does it make sense that the checkpoints are where they are?
G1: Make sure cell has nutrients, energy, undamaged DNA, and positive signals
G2: Make sure no damaged DNA
M: DNA evenly distributed
What occurs during DNA replication? What phase of the cell cycle is this associated with?
During DNA replication, DNA is duplicated and split between two identical copies (S)
What is mitosis? What is the end result of mitosis?
Cell division resulting in two identical daughter cells to the parent and sibling
How does the cell know when it’s time to grow/replicate?
Growth response - ligands attach from w/in and outside the cell to signal it to grow/replicate
Positive regulators vs negative regulators
Positive: Approves cell cycle progression
Negative: Blocks cell cycle progression
What are CDKs?
What do they do?
When are they present in the cell?
Enzymes responsible for activating and deactivating cells in cycle that are using ATP - usually present and inactive at every stage of cell cycle
What are cyclins? What do they do? When are they present in the cell?
Proteins that activate CDKs by binding to them - made when needed and serve different functions @ each phase
What is p53? How does it address DNA damage?
Negative regulator that detects and responds to damages (present during G1) - produces CDK inhibitors, activates, repair enzymes and can activate apoptosis
What is apoptosis? Where do apoptotic signals come from and under what circumstances is it triggered?
Programmed cell death - signal comes from p53 when a cell is beyond repair
