Cell Cycle (College Board AP® Biology): Flashcards
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- FrontThe Cell Cycle
Define cell cycle.
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Cards in this collection (25)
Define cell cycle.
Cell cycle is the highly regulated sequence of events that occurs between one cell division and the next, controlling the growth and reproduction of eukaryotic cells.
What are the three main phases of the cell cycle?
Interphase (G1, S and G2)
Mitosis (nuclear division)
Cytokinesis (division of the cytoplasm)
What happens during the G1 phase of interphase?
The cell is metabolically active, duplicating its organelles and cytosolic components.
During the phase, DNA replicates to form two sister chromatids connected at a centromere.
During the S phase, DNA replicates to form two sister chromatids connected at a centromere.
What happens during the G2 phase of interphase?
Protein synthesis occurs
ATP is produced in large quantities
Centrosomes replicate
True or False?
A cell in the G0 phase can never re-enter the cell cycle.
False.
Cells in G0 have stopped dividing, but they can re-enter the cell cycle in response to appropriate chemical signals.
Define mitosis.
Mitosis is a form of nuclear division that ensures the transfer of a complete genome from a parent cell to two genetically identical daughter cells.
Why is the production of genetically identical cells by mitosis important?
It is essential for:
growth
tissue repair
asexual reproduction
What are the four stages of mitosis, in order?
Prophase
Metaphase
Anaphase
Telophase
During , spindle fibers align the chromosomes along the equator of the cell.
During metaphase, spindle fibers align the chromosomes along the equator of the cell.
What happens to the sister chromatids during anaphase?
The spindle fibers shorten, pulling the sister chromatids apart to opposite poles of the cell, where they become chromosomes in their own right.
Define cytokinesis.
Cytokinesis is the division of the cytoplasm and organelles between the two new daughter cells, following mitosis.
How does cytokinesis differ between animal cells and plant cells?
Animal cells: a cleavage furrow forms and pinches the cell in two
Plant cells: a cell plate develops, because the rigid cell wall prevents a cleavage furrow
Define checkpoint.
Checkpoint is a control point in the cell cycle that a cell must pass through before it can progress to the next stage, ensuring the cell is ready to continue dividing.
What are three things that checkpoints assess before a cell can progress through the cell cycle?
The cell is large enough
The DNA has been replicated correctly
The necessary nutrients are available
Define cyclins.
Cyclins are proteins whose levels change throughout the cell cycle; they bind to cyclin-dependent kinases to form complexes that trigger the next stage of the cell cycle.
Define cyclin-dependent kinases.
Cyclin-dependent kinases are enzymes present at a constant concentration throughout the cell cycle; they are inactive until they bind to cyclins, after which they phosphorylate other molecules to activate them.
Cyclins bind to cyclin-dependent kinases, producing that trigger the next stage of the cell cycle.
Cyclins bind to cyclin-dependent kinases, producing complexes that trigger the next stage of the cell cycle.
True or False?
Cyclin-dependent kinases are active even when they are not bound to cyclins.
False.
Cyclin-dependent kinases are inactive until they bind to cyclins; only then can they phosphorylate other molecules to activate them.
How do cyclin-dependent kinases activate other molecules once they are bound to cyclins?
They phosphorylate the other molecules, adding a phosphate group that switches them on.
What are the two possible outcomes of a disruption to the cell cycle?
Cancer
Apoptosis (programmed cell death)
How can cancer develop as a result of cell cycle disruption?
Cancer can develop due to uncontrolled cell division.
Define apoptosis.
Apoptosis is programmed cell death; it destroys cells that contain dangerous mutations and removes cells that are no longer needed during development.
During embryonic development, the fingers are joined by webs of skin that are later removed by .
During embryonic development, the fingers are joined by webs of skin that are later removed by apoptosis.
True or False?
Apoptosis allows the destruction of cells that contain dangerous mutations.
True.
Apoptosis (programmed cell death) removes cells with dangerous mutations as well as cells that are no longer needed during development.
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