If there are two sets of 21 chromosomes in a rat's lung cell, how many total chromosomes are there in a cell that undergoes mitosis?
Answer: 42
Right.
To determine the total number of chromosomes in a cell undergoing mitosis, you need to understand the process of mitosis and how it affects chromosome numbers.
Mitosis is the cell division process where a single cell divides into two identical daughter cells. In this process, the replicated DNA is distributed equally between the two daughter cells, ensuring that they have the same number of chromosomes as the parent cell.
Given that a rat's lung cell has two sets of 21 chromosomes, we can conclude that the rat has a diploid chromosome number of 42 (2 sets x 21 chromosomes per set).
During mitosis, each chromosome is replicated, resulting in two identical copies, called sister chromatids, held together by a structure called the centromere. When the cell divides, each daughter cell receives one chromatid from each replicated chromosome, resulting in two daughter cells with the same chromosome number as the parent cell.
Therefore, in a cell undergoing mitosis, there would still be a total of 42 chromosomes, distributed equally between the two daughter cells.