Cell Cycle Flashcards
What is the cell cycle?
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A series of phases (G1, S, G2, M) that a cell goes through to grow and divide.
What are the main phases of the cell cycle?
• G1 (Gap 1)
• S (Synthesis)
• G2 (Gap 2)
• M (Mitosis)
What happens during G1 phase?
• Cell grows and matures
• Synthesizes RNA and proteins needed for DNA replication
• Normal metabolism continues
What happens during S phase?
• DNA replication occurs
• Histone proteins are produced
• RNA/protein synthesis slows down
What happens during G2 phase?
• Cell prepares for mitosis
• Organelles like centrioles and proteins (e.g., microtubules) are synthesized
• MPF (Mitosis Promoting Factor) is produced
What is the M phase?
The phase where mitosis and cytokinesis occur, resulting in two daughter cells.
What are the stages of mitosis?
• Prophase
• Metaphase
• Anaphase
• Telophase
What happens during prophase?
Chromatin condenses into visible chromosomes
• Nuclear envelope breaks down
• Mitotic spindle forms
What happens during metaphase?
• Chromosomes align at the equator
• Attach to kinetochore fibers
What happens during anaphase?
Sister chromatids are pulled to opposite poles by spindle fibers
What happens during telophase?
• Chromosomes decondense
• Nuclear envelope re-forms
• Cytokinesis begins
What’s the difference between cytokinesis in plant and animals
Animals: Cleavage furrow pinches the membrane
• Plants: Vesicles with cellulose fuse to form a new cell wall
What are cyclins?
Regulatory subunits of cyclin-dependent kinases (CDKs) that fluctuate during the cell cycle.
What are CDKs?
Catalytic proteins that require binding to cyclins to become active.
What is MPF (Maturation-Promoting Factor)?
A cyclin-CDK complex that triggers entry into mitosis.
Why are checkpoints important in the cell cycle?
To ensure each phase is properly completed and DNA is intact before moving on.
What phases have major checkpoints?
• G1 checkpoint (before S phase)
• G2 checkpoint (before M phase)
• Metaphase checkpoint (before chromatid separation)
What phases have major checkpoints?
. Cell cycle phases in order?
G1 → S → G2 → M
Mitosis phases in order
Prophase → Metaphase → Anaphase → Telophase
Can you described the 4 phases during the cell cycle?
The cell cycle consists of four main phases: G1, S, G2, and M. In the G1 phase, the cell grows, produces RNA and proteins, and prepares for DNA replication. During the S phase, DNA is replicated, and histone proteins are synthesized to package the new DNA.
The G2 phase follows, where the cell continues to grow and produces organelles and proteins needed for mitosis, including the Mitosis Promoting Factor (MPF). Finally, in the M phase, mitosis occurs in four steps: prophase, metaphase, anaphase, and telophase. This is followed by cytokinesis, which divides the cytoplasm, forming two daughter cells. Together, these phases ensure proper cell growth and division.
