When are chromosomes visible during the entirety of the cell cycle?
A. only during interphase
B. only during G2 phase
C. only during mitosis
D. only during G1 phase
A. only during interphase
Chromosomes are visible during mitosis. So, the correct answer is C. only during mitosis.
To determine when chromosomes are visible during the entirety of the cell cycle, we need to understand the different phases of the cell cycle.
The cell cycle consists of interphase and mitosis. Interphase is the longest phase and has three subphases: G1 (Gap 1), S (Synthesis), and G2 (Gap 2). During interphase, the cell prepares for cell division by growing and replicating its DNA.
Mitosis is the process of cell division that results in two daughter cells with the same number of chromosomes as the parent cell. Mitosis has four phases: prophase, metaphase, anaphase, and telophase. During mitosis, the condensed chromosomes become visible under a microscope.
Now, let's go through the options:
A. Only during interphase: This is incorrect because chromosomes are not typically visible during interphase. The DNA is in the form of chromatin, which is less condensed and spread out within the nucleus.
B. Only during G2 phase: This is incorrect because chromosomes are not visible during G2 phase. In G2 phase, the cell is preparing for mitosis by growing and synthesizing necessary proteins and organelles.
C. Only during mitosis: This option is partially correct. During mitosis, the chromosomes become highly condensed and visible. However, chromosomes are not visible during the entire mitosis process, only during the four phases mentioned earlier.
D. Only during G1 phase: This is incorrect because chromosomes are not visible during G1 phase. In G1 phase, the cells are growing, performing their normal functions, and preparing for DNA replication.
To summarize, chromosomes are only visible during a portion of the cell cycle, specifically during the phases of mitosis. Therefore, the correct answer is C. only during mitosis.