Which of the following does NOT occurr during mitosis?
a. condensation of the chromosomes
b. separation of sister chromotids
c. replication of DNA d. spindle formation
Which of the following does not occur during mitosis?
(A) condensation of the chromosomes
(B) replication of the DNA
(C) separation of sister chromatids
(D) spindle formation
Answer to question 1
Mitosis is a part of the cell cycle when replicated chromosomes are separated into new nuclei. It gives rise to genetically identical cells having the same number of chromosomes.
Mitosis has four phases namely prophase, metaphase, anaphase and telophase. Condensation of chromosomes occurs in the prophase stage of mitosis. Separation of sister chromatids and spindle formation occurs in anaphase.
However, replication of DNA is not a part of mitosis. It occurs during the S phase of the cell cycle, which occurs before mitosis.
Hence, c. replication of DNA is the correct answer.
Answer to question 2
The cell cycle is the series of events that takes place in a cell that cause it to divide into two daughter cells. It includes five stages namely G1 phase, S phase, G2 phase, mitosis and cytokinesis.
Correct answer: The event that does not occur during mitosis is replication of DNA.
Reason for correct answer:
Option.B is given as ‘replication of DNA’.
The mitosis is the process of cell division during which one cell gives rise to two genetically identical daughter cells. It involves four phases namely prophase, metaphase, anaphase and telophase. During this process, condensation of the chromosomes, separation of sister chromatids and spindle formation occurs to produce identical daughter cells. The replication of DNA occurs in the S phase or synthetic phase of cell cycle prior to the mitosis. Hence option.B is correct.
Reason for incorrect answer:
Option.A is given as ‘condensation of the chromosomes’.
The condensation of chromosomes occurs in the prophase of mitosis. Hence option.A is incorrect.
Option.C is given as ‘separation of sister chromatids’.
The separation of sister chromatids occurs in anaphase of the mitosis. Hence option.C is incorrect.
Option.D is given as ‘spindle formation’.
The spindle formation occurs in the prophase of mitosis. Hence option.D is incorrect.
Answer to question 3
Cell cycle: It is a sequence of events by the genome of the cells duplicates and the cells divides into two daughter cells. It has two main phases- Interphase and M-phase. M-phase is the mitotic phase where actual division takes place. The interphase is sub divided into four phases- G1, S, G2, G0 phase.
Mitosis: It was introduced by “Walter Flemming” in 1882. In this process the chromosomes are equally repliacted into two daughter cells.
b) Separation of sister chromatids: during anaphase stage of mitosis, sister chromatids do not separate because they are hold together at their centromeres by cohesin protein. so, option b is correct.
a) condensation of the chromosomes: in prophase stage of mitosis, the chromatin gets condenses into fully formed chromosomes. so, option a) is incorrect.
c)replication of DNA: chromosomes gets replicated in the cell and divides equally in two daughter cells so, option c is incorrect.
d)spindle formation: At metaphase of the mitosis spindle gets formed by microtubules at the kinetochore. so, option d is incorrect,
Answer to question 4
Mitosis is the process by which a single cell divides into two. It has mainly two stages karyokinesis and cytokinesis. It is a form of equational division because chromosome number is same in both parent and offspring.
For the above question the correct answer is option c . Yes this option is wrong because it happens during meiosis.
In mitosis the chromosomes are split and the chromatids are moved to the opposite poles by the spindle fibres. However in meiosis the homologous chromosomes are separated by the spindle fibres.This option thus corresponds to anaphase of meiosis and not of mitosis.
Hence the third option is not applicable for mitosis.
Others options are correct with respect to mitosis because
Condensation of chromosomes occur in prophase.
Chromosomes move to equator during metaphase.
Finally during telophase two nuclei are formed with full genetic information.