Chromosome and chromatid numbers during cell cycle phases?
A diploid cell in G1 has 6 chromosomes. How many chromosomes and how many chromatids are present in each of the following stages?Here is what I am guessing- G1: 6 chromosomes ; 6 chromatids \n\n- G2: 6 chromosomes ; 12 chromatids \n\n- Prophase: 6 chromosomes; 12 chromatids \n\n- Metaphase: 6 chromosomes; 12 chromatids \n\n- Anaphase: 12 chromosomes; 12 chromatids \n\n- Telophase: 12 chromosomes; 12 chromatids
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Bodhi V. answered • 08/09/19
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Effective Biology, Anatomy, and Physiology Teacher
It looks like you've got it down. The number of Chromatids double in Synthesis phase, but the number of chromosomes stay the same. Anaphase doubles the chromosome number, but does not affect the chromatid number. All around solid job.
John N. answered • 05/31/19
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You are correct in all of your guesses. The confusing part is that what constitutes a chromosome is different at different times in the cell cycle, depending upon whether the DNA has replicated or not, and when the sister chromatids separate, changing a chromosome from containing 2 chromatids to only 1.
So G1 1 Chromosome = 1 Chromatid
S is DNA replication so 1 Chromosome = 2 chromatids
G2, Prophase, and Metaphase: 1 Chromosome = 2 chromatids
Anaphase and Telopphase: 1 Chromosome = 1 chromatid
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Sorita D.
During the later stages of cell division these chromatids separate longitudinally to become individual chromosomes. Chromatid pairs are normally genetically identical, and said to be homozygous; however, if mutation(s) occur, they will present slight differences, in which case they are heterozygous.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: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 humansthere 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: 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 reformed08/04/19