August 31(Mitosis and Meiosis) [_/17]
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What is the cell cycle? What are the stages of the cell cycle?
The cell cycle is the series of steps a cell goes through to grow, copy its DNA, and divide into two new cells.
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What is G0 and how is it different from G1?
G₀ is a resting state where the cell leaves the cell cycle and is not preparing to divide.
G₁ is an active stage where the cell grows, performs normal functions, and prepares to copy its DNA.
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Centrosome?
Located at the opposite ends (poles) of the cell and organizes spindle fibers.
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What’s the difference between haploid and diploid?
Haploid (n) cells have one set of chromosomes, while diploid (2n) cells have two sets of chromosomes, one set from each parent.
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G1 phase, what happens?
A newly formed cell grows physically larger, copies its internal organelles, and makes the proteins needed to replicate its DNA.
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What are the stages of mitosis?
The 4 main stages of mitosis are:
P → M → A → T
Prophase – Chromosomes condense and become visible, and the nuclear membrane breaks down.
Metaphase – Chromosomes line up in the middle of the cell.
Anaphase – Sister chromatids separate and move to opposite sides of the cell.
Telophase – Two new nuclei form around the chromosomes.
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Spindle fiber?
Fibers that attach to and move/pull chromosomes during division.
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What is a sister chromatid, and how does it differ from a chromosome?
A sister chromatid is one of two identical halves of a replicated chromosome, joined together at a central region called the centromere.
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S phase, what happens?
The cell copies its DNA and duplicates the centrosome.
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All stages of cell cycle, what happens and how do you identify them?
Prophase – Chromosomes condense and become visible, and the nuclear membrane breaks down.
Metaphase – Chromosomes line up in the middle of the cell.
Anaphase – Sister chromatids separate and move to opposite sides of the cell.
Telophase – Two new nuclei form around the chromosomes.
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Sister chromatid?
One of the two identical copies of a replicated chromosome.
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G2 phase, what happens?
The cell undergoes final growth, produces essential proteins and organelles, and checks its DNA for damage before entering mitosis.
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Centromere?
The middle region of a chromosome that holds the sister chromatids together.
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Metaphase plate?
The middle of the cell where chromosomes line up during metaphase.
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M phase, what happens?
A cell divides its copied DNA and cytoplasm to create two identical daughter cells.
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Kinetochore?
The attachment point on the centromere where spindle fibers connect.
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What is the chromosomal number at each point in the cell cycle?
In a human cell, there are 46 chromosomes during G1, S, G2, prophase, and metaphase.
During anaphase, the number temporarily becomes 92 chromosomes, and after cytokinesis, each daughter cell has 46 chromosomes.