H. During which three phases are individual chromosomes no longer visible?
Think and discuss: Why is it important that the cell’s DNA is duplicated before cell division?
Challenge: Human cells have 46 chromosomes. Each chromosome consists of a pair of identical
chromatids attached together by a structure called a centromere. Once the chromosome has split, each
chromatid is called a daughter chromosome. At the end of cytokinesis, how many daughter chromosomes
will be found in each cell? Explain.
The Correct Answer and Explanation is :
Answer:
Individual chromosomes are no longer visible during Interphase, Telophase, and Cytokinesis.
Explanation:
DNA duplication before cell division is crucial for ensuring that each daughter cell receives a complete set of genetic material. If DNA were not duplicated before division, the resulting daughter cells would end up with only half the necessary genetic information, leading to cell dysfunction or death. This process ensures genetic continuity and stability across generations of cells.
During interphase, the cell prepares for division by growing and replicating its DNA. At this stage, chromosomes are present as loosely packed chromatin, making them invisible under a microscope. When the cell enters mitosis, chromosomes condense and become visible, allowing them to be properly aligned and separated.
After chromosomes are pulled apart during anaphase, telophase begins, where chromosomes start de-condensing back into chromatin. The nuclear membrane reforms around the two sets of separated chromosomes, making individual chromosomes indistinct. Finally, during cytokinesis, the cell cytoplasm divides, fully forming two new daughter cells. Since chromatin remains uncondensed, individual chromosomes are no longer visible.
Challenge Answer:
Each human cell starts with 46 chromosomes, each consisting of two identical chromatids. During mitosis, these chromatids are separated and become individual daughter chromosomes. Since each chromatid is now an independent chromosome, each new daughter cell will have 46 daughter chromosomes at the end of cytokinesis.
This ensures that both daughter cells have a complete and identical set of chromosomes, preserving genetic information across cell generations.
Now, I will generate an image illustrating the process of cell division.
Here is an illustration of the phases of cell division (mitosis), showing key stages like Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis. The diagram highlights important structures such as chromatids, centromeres, spindle fibers, and the nuclear membrane. Let me know if you need any modifications!
