II CELL CYCLE CELL DIVISION MITOSIS AND MEIOSIS 3 15 PTS In

II. CELL CYCLE, CELL DIVISION, MITOSIS AND MEIOSIS 3. [1.5 PTS] In a diploid organism where the haploid chromosome number (N) = 8, how many chromatids are present in a cell in:

(a) mitotic metaphase?

(b) meiotic metaphase I?

(c) meiotic metaphase II?

Solution

CELL CYCLE: It is a series of events which takes place in a cell leading to its division and DNA duplication (DNA replication) to produce two daughter cells.

CELL DIVISION: It is a process by which a parent cell divides into two or more daughter cells. Cell division is usually the formation of new cells followed by karyokinesis ( the division of nucleus).

MITOSIS: This is the process in which mother cell (somatic cell) divides into 2 diploid daughter cell, though the no. of chromosome remain constant that\'s why it is called as equational cell division.

MEIOSIS: In this type of cell division the germ cells divide and form 4 new daughter cells, which are having half no. of chromosome of the mother cell. That\'s why this type of cell division is called as reductional cell division.

Problem:

Solution:

Haploid no. of chromosome (N) =8 => 2N=16 chromosomes

(a) Mitotic metaphase: 64 no. of chromatids (16*2=32 no of chromosomes, each chromosome is having 2 chromatids, so 32*2=64)

(b) meiotic metaphase I: 64 no. of chromatids (same as mitotic metaphase, though cell division is different but no of the chromosome will remain same)

(c) meiotic metaphase II: 32 no. of chromatids (no of chromosome reduced to half \"16\" after meiosis-I, so chromatids in meiosis-II metaphase will be 16*2=32)