Chapter 2.1. Animation Activity: Cell Cycle and Mitosis

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Correct. The major phases of the cell cycle are interphase and M phase. All of the other phases listed represent subdivisions of either interphase or M phase.

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Incorrect. The major phases of the cell cycle are interphase and M phase. All of the other phases listed represent subdivisions of either interphase or M phase.

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Correct. A cell that has exited from the cell cycle is in G0 phase. This phase is similar to G1 in that each chromosome consists of a single chromatid as the chromosomes have not undergone DNA replication. A cell in G0 can remain in this phase of the cell cycle indefinitely. The difference between G1 and G0 is that a cell in G1 is actively preparing to enter S phase.

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Incorrect. A cell that has exited from the cell cycle is in G0 phase. This phase is similar to G1 in that each chromosome consists of a single chromatid as the chromosomes have not undergone DNA replication. A cell in G0 can remain in this phase of the cell cycle indefinitely. The difference between G1 and G0 is that a cell in G1 is actively preparing to enter S phase.

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Correct. At the G1 phase of the cell cycle, each chromosome consists of a single chromatid and each chromatid consists of a single double-stranded DNA molecule. Therefore, a cell that normally has 12 chromosomes will have 12 DNA molecules in G1.

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Incorrect. At the G1 phase of the cell cycle, each chromosome consists of a single chromatid and each chromatid consists of a single double-stranded DNA molecule. Therefore, a cell that normally has 12 chromosomes will have 12 DNA molecules in G1.

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Correct. During the G2 phase, each chromosome consists of two identical chromatids. The cell undergoes several biochemical events during G2 that are required for chromosome condensation, spindle formation, and nuclear membrane disassembly that take place during M-phase.

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Incorrect. During the G2 phase, each chromosome consists of two identical chromatids. The cell undergoes several biochemical events during G2 that are required for chromosome condensation, spindle formation, and nuclear membrane disassembly that take place during M-phase.

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Correct. Chromosomes first begin the process of condensation and spindle fibers begin to form during prophase, a subdivision of mitosis. Chromosome condensation continues through prometaphase when the spindle fibers actually attach to the chromosomes and the nuclear membrane breaks down.

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Incorrect. Chromosomes first begin the process of condensation and spindle fibers begin to form during prophase, a subdivision of mitosis. Chromosome condensation continues through prometaphase when the spindle fibers actually attach to the chromosomes and the nuclear membrane breaks down.

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Correct. Although the number of DNA molecules double between G1 and G2 of the cell cycle, the number of chromosomes remain the same. Chromosomes can be counted by counting the number of centromeres. Each chromosome in G2 consists of two double-stranded DNA molecules (chromatids) joined by a single centromere.

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Incorrect. Although the number of DNA molecules double between G1 and G2 of the cell cycle, the number of chromosomes remain the same. Chromosomes can be counted by counting the number of centromeres. Each chromosome in G2 consists of two double-stranded DNA molecules (chromatids) joined by a single centromere.

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Correct. During anaphase each chromosome present in metaphase separates into two chromosomes, each with a single double-stranded DNA molecule. Therefore, during anaphase the chromosome number is temporarily doubled until the cells finish the process of cell division. If a cell normally contains 12 chromosomes, it will contain 24 during anaphase.

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Incorrect. During anaphase each chromosome present in metaphase separates into two chromosomes, each with a single double-stranded DNA molecule. Therefore, during anaphase the chromosome number is temporarily doubled until the cells finish the process of cell division. If a cell normally contains 12 chromosomes, it will contain 24 during anaphase.

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Correct. During metaphase each chromosome consists of two identical, double-stranded DNA molecules. Therefore, if a cell normally contains 12 chromosomes, there will be 24 molecules of DNA during metaphase.

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Incorrect. During metaphase each chromosome consists of two identical, double-stranded DNA molecules. Therefore, if a cell normally contains 12 chromosomes, there will be 24 molecules of DNA during metaphase.

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Correct. If a spindle fiber fails to attach to a chromosome during prometaphase, that chromosome will fail to migrate to the metaphase plate and will often be lost when the nuclear membranes reform during telophase. This is the most likely explanation for the loss of a single chromosome in both of the daughter cells during mitosis.

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Incorrect. If a spindle fiber fails to attach to a chromosome during prometaphase, that chromosome will fail to migrate to the metaphase plate and will often be lost when the nuclear membranes reform during telophase. This is the most likely explanation for the loss of a single chromosome in both of the daughter cells during mitosis.

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Correct. If a chromosome failed to separate into two chromatids during anaphase, both chromatids would travel to the same daughter cell during anaphase. This would mean that one daughter cell would have an extra chromosome and the other daughter cell would be missing a chromosome relative to the original cell that entered mitosis.

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Incorrect. If a chromosome failed to separate into two chromatids during anaphase, both chromatids would travel to the same daughter cell during anaphase. This would mean that one daughter cell would have an extra chromosome and the other daughter cell would be missing a chromosome relative to the original cell that entered mitosis.