Question

In the S phase of the cell cycle
A. Amount of DNA doubles in each cell
B. Amount of DNA remains same in each cell
C. Chromosome is increased
D. Amount of DNA is reduced to half in each cell

Answer 1

Hint: The time from the end of one mitosis to the beginning of the next is called interphase. Quantitative cytophotometric analysis of metabolic nuclei after Feulgen staining initially showed that DNA replication occurs during interphase. The interphase phase consists of sub-phases G1, S and G2. G1 is the resting period, S is the period of DNA replication, and G2 is the resting period after DNA replication.

Complete answer:
Most cells divide more than once in a lifetime. Together, they go through a series of regular events that make up the cell cycle.
The time from the end of one mitosis to the beginning of the next is called interphase. This is a step between the end of the last telophase and the next prophase. This is the longest period of cell division.
The three stages of interphase are called .
Step S is an intermediate step between steps and . After the completion of phase , phase S begins. This is a highly specialized stage of the liver, and the word S means synthetic.
 In fact, at this stage, DNA synthesis occurs. Before the cell can divide, a new copy of the chromosome must be made. To make a new copy of a chromosome, you need to duplicate the long DNA molecule of each chromosome and accumulate a new set of chromosomal proteins in the DNA to form chromatin or chromosome.
Eventually, each chromosome is copied into two complete chromosomes, linked to the centrosome up to stage M, which immediately follows.

Hence in my phase the amount of DNA doubles in each cell but the number of chromosomes remains the same so the correct option is (A).

Additional information:
The length of the cell cycle varies greatly from cell to cell. The shortest cell cycle occurs early in the embryo and can last as little as minutes. The cell cycle of growing eukaryotic cells lasts from minutes to more than hours, and their duration varies greatly within cell populations.

Note:
The S-phase is also known as the invisible M-phase and is the DNA synthesis phase. At this stage, histones are also synthesized, which bind to the newly cloned DNA. At this stage, the euchromatic regions of the genome are replicated earlier than the heterochromatic regions. In addition, in some cells, the G-C-rich regions of the genome are replicated earlier than the A-T-rich regions.
During nuclear interphase, some changes occur at the molecular level that cannot be seen under a microscope. Interphase is a period of intense biosynthetic activity, during which the cell size doubles.