Mitotic anaphase differs from metaphase in possessing[1991]a)same number of chromosomes and same number of chromatidsb)half number of chromosomes and half number of chromatidsc)half number of chromosomes and same number of chromatidsd)same number of chromosomes and half number of chromatidsCorrect answer is option 'D'. Can you explain this answer?

Question

Accepted Answer

Mitotic anaphase differs from metaphase in possessing same number of chromosomes and half number of chromatids. While during metaphase, chromosomes become maximally distinct due to further contraction and thus size of chromosomes is measured at mitotic metaphase.

Answer

Explanation:

Mitosis is a process of cell division in which a cell divides into two daughter cells, each containing the same number of chromosomes as the parent cell. Mitotic anaphase is the stage of mitosis in which the sister chromatids separate and move towards opposite poles of the cell. This stage differs from metaphase in possessing the following features:

Same number of chromosomes: During both metaphase and anaphase, the cell contains the same number of chromosomes as in the parent cell. This is because the chromosomes have already replicated during the S-phase of interphase.

Half number of chromatids: In metaphase, the chromosomes are aligned at the equator of the cell, with each chromosome composed of two identical chromatids held together by a centromere. However, in anaphase, the sister chromatids separate and move towards opposite poles of the cell. As a result, the number of chromatids is reduced to half of that in metaphase.

Conclusion:

Hence, the correct answer is option D, which states that mitotic anaphase differs from metaphase in possessing the same number of chromosomes and half the number of chromatids.

Answer

In the metaphase stage, all the chromosomes are arranged at the cell equator. All the chromosomes have two chromatids, joined at the centromere. These are called sister chromatids. The centromere splits in the anaphase stage and the two sister chromatids go to opposite poles. They are now called as chromosomes. They have single chromatid which will duplicate into two sister chromatids in the S phase. Thus, at the anaphase stage number of chromosomes remains the same even as the number of chromatids is reduced to one-half due to the splitting of the centromere.

Answer

L think no correct answer because number of chromosome double in anaphase

Answer

D. because in anaphase chromatids separate and each end receives only one chromatid from each chromosome.

Answer

Students find challenging (and is known to appear on the DAT) is the number of chromosomes and chromatids present during the various stages of meiosis and mitosis in eukaryotes. To first clarify this topic, it is first essential to understand some basic definitions.

Chromatin is the general packaging of DNA around histone proteins – this arrangement of DNA helps to condense DNA to fit within the nucleus of the cell. Throughout most of the cell cycle, DNA is packaged in the form of chromatin. However, during mitosis and meiosis, chromatin exists in an additional level of organization known as a chromosome. Chromosomes are an even denser packaging of chromatin that are visible with a light microscope, particularly during metaphase. Chromosomes can exist in duplicated or unduplicated states. At the beginning of mitosis, for example, a chromosome consists of two sister chromatids – chromatids are the term used to describe the chromosome in its duplicated state. Let’s try to tie all of this information together and see how it applies to chromosome and chromatid count during the various stages of cell replication.

First, during the S phase of interphase, the genetic material of a cell is duplicated. A human has 46 chromosomes (a set of 23 you inherit from your mother, and a set of 23 from your father). After the genetic material is duplicated and condenses during prophase of mitosis, there are still only 46 chromosomes – however, they exist in a structure that looks like an X shape:

For clarity, one sister chromatid is shown in green, and the other blue. These chromatids are genetically identical. However, they are still attached at the centromere and are not yet considered separate chromosomes. Thus, the above picture represents one chromosome, but two chromatids. During prophase and metaphase of mitosis, each chromosome exists in the above state. For humans, this means that during prophase and metaphase of mitosis, a human will have 46 chromosomes, but 92 chromatids (again, remember that there are 92 chromatids because the original 46 chromosomes were duplicated during S phase of interphase). It is helpful to see this visualized (for visual simplicity, a 2n=8 arrangement of chromosomes will be demonstrated, rather than the 2n=46 arrangement of chromosomes in humans):

As the above image shows, there are 8 chromosomes present, but 16 chromatids. Similarly, in humans (2n=46), there are 46 chromosomes present during metaphase, but 92 chromatids.

It is only when sister chromatids separate – a step signaling that anaphase has begun – that each chromatid is considered a separate, individual chromosome. Pictured below, we see how the 2n=8 cell from above has progressed from having 8 chromosomes to 16 chromosomes:

Now that the sister chromatids have separated, each chromatid is also considered a chromosome. During anaphase, we now have a total of 16 chromosomes and 16 chromatids – in short, each chromatid is now a chromosome. Similarly, in humans, there are 92 chromosomes present and 92 chromatids during anaphase. These numbers remain the same during telophase. It is only after the end of mitosis – when the dividing cells have fully separated and the membranes have reformed – that the normal chromosome number is restored to the cell. Below is a table summarizing the chromosome and chromatid number during mitosis in humans:

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