Yes. DNA replication is possible without cell decisions. Endomitosis is the proliferation of chromosomes found in a set in the nucleus without cytokinesis and karyokinesis leads to several copies within each cell. It is of two kinds, which are described below.
• Here chromosomes split and redivide without partition of chromatids so that such chromosomes turned into multistranded with several copies of DNA.
• Such polytene (several stranded) chromosomes persist in the permanent prophase stage and do not endure the cell cycle e.g., polytene salivary glands) the chromosome of Drosophila.
• Here several sets of chromosomes do not change.
ii. Polyploidy (endoduplication)
● Here all chromosomes in a set split and its chromatids are isolated but the nucleus does not split.
● This raises the number of sets of chromosomes in the nucleus ( 4 x, 8 x…..).
● This rise in sets of chromosomes is known as polyploidy. It can be stimulated by colchicine (alkaloid obtained from Colchicum autumnale (family –Liliaceae). These chromosomes are normal and endure a cell cycle.Answered by Pragya Singh | 1 year ago
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
Can there be mitosis without DNA replication in the ‘S’ phase?
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.
What is the significance of meiosis?
Distinguish anaphase of mitosis from anaphase 1 of meiosis.