Question

which phase of mitosis is responsible for the condensed structure of chromosomes?
A. Interphase
B. Prophase
C. Metaphase
D. Anaphase
E. Telophase

Answer 1

Chromosomes are long molecules of DNA that contain part or all of the body's genetic material. Most eukaryotic chromosomes have packaging proteins called histones that help chromosomes to stay compact inside the nucleus.

Complete answer: Prophase is a mitosis stage characterized by spindle formation, shortening and thickening of chromosomes, breaking of the nuclear envelope. It is a stage in which the chromatin is condensed into a chromosome. It is made up of two sister chromatids joined together by a centromere. Cohesin form rings that hold the sister chromatids together, whereas condensin forms a ring that coils the chromosomes into highly compact forms. Metaphase is the second stage that is characterized by the movement of chromosomes to the cell equator, which is mediated by the kinetochore microtubules of the spindle fibres. The alignment of the chromosomes in the equatorial plane of the shaft, the metaphase plate, marks the end of the metaphase. Then, anaphase is the third mitosis stage characterized by the release of sister chromatids, followed by their movement to the opposite poles of the spindle. Lastly, telophase is the final stage of mitosis where chromosomes are present at the opposite extreme poles surrounded by a nucleus.
Thus, the option (B) is correct.

Note: The various types of chromosomes are metacentric, submetacentric, acrocentric and telocentric. The addition or loss of chromosomes from the normal set is called aneuploidy. The common form of aneuploidy is trisomy or the presence of an extra chromosome in the cell.