Question

intro activity - cell division
name:
in order for most organisms to grow, repair damaged cells, and maintain their life functions, new cells are needed. each new cell, or daughter cell, must contain the same genetic information as the original cell, or parent cell. how are these new, genetically identical cells produced?
procedure:

1. the diagrams show onion root - tip cells before and after the cells have divided to form new cells. the tip of an onion root - tip is an active growing region. the cells in this region are actively dividing to produce new cells.
2. study the diagrams. compare the number and characteristics of the chromosomes in the parent cell to the number of chromosomes in the two daughter cells.

analysis:

1. what do you notice about the number of chromosomes in the parent cell compared to the number of chromosomes in the two daughter cells?
2. what do you notice about the characteristics of each chromosome in the three cells?
3. how do you think it is possible to start with 16 chromosomes in the parent cell and end up with 16 chromosomes in each of the two daughter cells?
4. a somatic cell (cell other than sperm and egg cells) in humans contains 46 chromosomes. if this cell divides, how many chromosomes do you think will appear in the two new daughter cells?

Explanation:

1. The number of chromosomes in the parent cell is equal to the total number of chromosomes in the two daughter cells combined, and each daughter cell has the same number of chromosomes as the parent cell (16 in this case). This is because of mitosis, which results in genetically - identical daughter cells with the same chromosome number as the parent.
2. The characteristics of each chromosome in the three cells (parent and two daughter cells) are the same as the daughter cells are produced by mitosis, which preserves the genetic information and thus the characteristics of the chromosomes.
3. Mitosis is the process by which this occurs. During mitosis, the chromosomes in the parent cell replicate (duplicate) during the interphase before cell division. Then, during the stages of mitosis (prophase, metaphase, anaphase, telophase), the replicated chromosomes are separated equally into two new nuclei, resulting in two daughter cells each with the same number of chromosomes as the parent cell.
4. In human somatic cell division (mitosis), each of the two new daughter cells will contain 46 chromosomes, just like the parent somatic cell, because mitosis produces genetically - identical cells with the same chromosome number.

Answer:

1. The number of chromosomes in the parent cell is the same as the number of chromosomes in each daughter cell (16).
2. The characteristics of each chromosome are the same in the parent and daughter cells as they are genetically identical due to mitosis.
3. Through the process of mitosis where chromosomes replicate and then are equally divided into two new nuclei.
4. 46 chromosomes will appear in each of the two new daughter cells.