If there are two sets of 21 chromosomes in a rats lung cell, how many total chromosomes are there in a cell that undergoes mitosis?
Answer: 42
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To determine the total number of chromosomes in a cell that undergoes mitosis, we need to understand what happens during this process. Mitosis is a type of cell division where a single cell divides into two identical daughter cells.
During mitosis, the cell goes through several stages, including prophase, metaphase, anaphase, and telophase. In the final stage, cytokinesis, the cell fully divides into two separate cells.
Before the cell enters mitosis, it undergoes a process called DNA replication. During DNA replication, each chromosome duplicates, resulting in two identical sister chromatids held together by a structure called the centromere.
Now, let's apply this knowledge to the scenario given. It is stated that there are two sets of 21 chromosomes in a rat's lung cell. This means that these 21 chromosomes are already duplicated, resulting in a total of 42 chromatids (2 sets of 21 chromosomes).
During mitosis, each chromatid will be separated from its sister chromatid and distributed equally into the two daughter cells. As a result, each daughter cell will receive the same number of chromosomes as the parent cell. Therefore, each daughter cell will have 42 chromosomes, which is the total number of chromatids in the parent cell.
Hence, the answer is 42 chromosomes.