Cells in phase
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The correct sequence of phases of the cell cycle is
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During cell growth, DNA synthesis takes place on
S-phase
-phase
phase
M phase
In S-phase (synthesis phase) of cell cycle, the chromosomes replicate. For this, their DNA molecules function as templates and form carbon copies. The DNA content doubles, i.e., 1C to 2C for haploid cells and 2C to 4C for diploid cells. As a result, duplicate sets of genes are formed. Along with replication of DNA, new chromatin fibres are formed which, however, remain attached in pairs and the number of chromosomes does not increase. As chromatin fibres are elongated chromosomes, each chromosome comes to have two chromatin threads or sister chromatids which remain attached at a common point called centromere."
When a cell has a stalled DNA replication fork, which checkpoint should be predominantly activated?
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A somatic cell that has just completed the S phase of its cell cycle, as compared to a gamete of the same species, has
twice the number of chromosomes and four times the amount of DNA
four times the number of chromosomes and twice the amount of DNA
twice the number of chromosomes and twice the amount of DNA
same number of chromosomes but twice the amount of DNA
In diploid cells (somatic cells) during phase, DNA content is 2C and chromosome number is 2n whereas in haploid cells (gamete) during phase, DNA content is 1C and chromosome number is n. S phase is marked by replication of DNA and the amount of DNA per cell is doubled, i.e., it becomes 4C in somatic cells, whereas chromosome number remains same, i.e., 2n. Thus, a somatic cell which has just completed S phase, will have 4C DNA content but 2n chromosome number, while the gamete cell has 1C DNA content and n chromosome number.
During which phase(s) of the cell cycle does the amount of DNA in a cell remain at 4C level if the initial amount is denoted as 2C?
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In the 'S' phase of the cell cycle:
amount of DNA doubles in each cell
amount of DNA remains the same in each cell
chromosome number is increased
amount of DNA is reduced to half in each cell
In S-phase (synthesis phase) of cell cycle, the chromosomes replicate. For this, their DNA molecules function as templates and form carbon copies. The DNA content doubles, i.e., 1C to 2C for haploid cells and 2C to 4C for diploid cells. As a result, duplicate sets of genes are formed. Along with replication of DNA, new chromatin fibres are formed which, however, remain attached in pairs and the number of chromosomes does not increase. As chromatin fibres are elongated chromosomes, each chromosome comes to have two chromatin threads or sister chromatids which remain attached at a common point called centromere."
