Analyse the events during every stage of cell cycle and notice how the following two parameters change

(i) number of chromosomes (N) per cell

(ii) amount of DNA content (C) per cell

Asked by Abhisek | 1 year ago |  201

1 Answer

Solution :-

(i) In mitotic division, the number of chromosomes remains the same as the parent cell at prophase and metaphase. At the anaphase stage of mitosis when

the sister chromatids separate and form two nucleus in telophase, each of them contains the same number of chromosomes as the parent cell.

● In meiotic division, the homologous chromosomes get separated into two different poles during anaphase-I. Thus, during prophase-I, metaphase-I and anaphase-I the cell contains the same chromosome number as the parent cell. As two separate nuclei are formed in telophase, each contains half the number of chromosomes compared to the parent cell.

● During meiosis-II, the sister chromatids are separated in anaphase-II. Thus the daughter cells retain their chromosome number the same as cells after meiosis I. So, the daughter cells contain N number of chromosome if the parent cell has 2N chromosomes.

 

(ii) S or synthesis phase indicates the period during which DNA replication or synthesis takes place. Throughout this time the amount of DNA per cell becomes double.

● If the initial amount of DNA is signified as 2C then it rises to 4C . During prophase, metaphase and anaphase of mitosis, the DNA content remain 4C .

● After the telophase, as the sister chromatids are separated into two separate nuclei, each nucleus contains 2C amount of DNA same as the parent cell in G1 phase. 

● In meiosis, the daughter cells after first division contains 2C volume of DNA which gets halved i.e., C after second division.

 

Answered by Pragya Singh | 1 year ago

Related Questions

Discuss with your teacher about

(i) haploid insects and lower plants where cell-division occurs.

(ii) some haploid cells in higher plants where cell-division does not occur.

Class 11 Biology Cell Cycle and Cell Division View Answer