If there are 48 duplicated chromosomes in a cell how many centromeres are there
Answers
Answer:
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.
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Answer:
24
Explanation:
Half of duplicated chromosome.