Can there be DNA replication without cell division? - Biology

Answer in Brief

Can there be DNA replication without cell division?



Indeed. Endomitosis is the process by which a set of chromosomes in the nucleus multiply without undergoing cytokinesis or karyokinesis, producing several copies in every cell. There are two varieties.

  1. Polyteny: In this case, chromosomes split and re-divide without chromatid separation, resulting in multistranded chromosomes that contain several copies of DNA. These polytene (many stranded) chromosomes, such as the Drosophila polytene (salivary glands) chromosome, have 512–1024 chromatids and do not go through the cell cycle. The quantity of chromosomal sets remains unchanged in this instance.
  2. Polyploidy (endoduplication): Here, the nucleus does not divide; instead, each set of chromosomes divides together with its chromatids. As a result, there are more sets of chromosomes in the nucleus (4x, 8x, etc.). We refer to this expansion in chromosomal sets as polyploidy. Granosan and colchicine have the ability to induce it. These chromosomes travel through the cell cycle and are normal.
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Chapter 10: Cell Cycle and Cell Division - Exercises [Page 172]


NCERT Biology Class 11
Chapter 10 Cell Cycle and Cell Division
Exercises | Q 15 | Page 172

Video TutorialsVIEW ALL [1]


Discuss with your teacher about haploid insects and lower plants where cell-division occurs.

Discuss with your teacher about some haploid cells in higher plants where cell-division does not occur.

Choose the ODD one out from the following terms given and name the CATEGORY to which the others belong:

Lumen, muscular tissue, connective tissue, pericardium

Choose the correct option.

Synapsis is pairing of ______.

Choose the correct option.

Spindle apparatus is formed during which stage of mitosis?

Choose the correct option.

How many meiotic divisions are necessary for the formation of 80 sperms?

Choose the correct option.

How many chromatides are present in anaphase-I of meiosis-I of a diploid cell having 20 chromosomes?

Choose the correct option.

In which of the following phase of mitosis chromosomes are arranged at the equatorial plane?

Choose the correct option.

Find incorrect statement.

Choose the correct option.

Histone proteins are synthesized during ______.

Answer the following question.

Students were shown some slides of cancerous cells. Teacher made a comment as if there would have been control at one of its cell cycle phase, there wouldn’t have been a condition like this. Which phase the teacher was referring to?

Answer the following question.

Some Mendelian crossing experimental results were shown to the students. Teacher informed that there are two genes located on the same chromosome. He enquired if they will be ever separated from each other?

Match the following column A with column B.

(Their events)
a. Leptotene 1. Crossing over
b. Zygotene 2. Desynapsis
c. Pachytene 3. Synapsis
d. Diplotene 4. Bouquet stage

Anaphase promoting complex APC is a protein degradation machinery necessary for proper mitosis of animal cells. If APC is defective in human cell, which of the following is expected to occur?

Centromere is required for ______.

Synapsis occur between ______.

In meiosis crossing over is initiated at ______.

Colchicine prevents the mitosis of the cells at which of the following stage______.

The paring of homologous chromosomes on meiosis is known as ______.

Write any three significance of mitosis.

Differentiate between mitosis and meiosis.

Differentiate cytokinesis in plant cells and animal cells.

Write about Pachytene of Prophase I.

Write about Pachytene and Diplotene of Prophase I

If a tissue has at a given time 1024 cells, how many cycles of mitosis had the original parental single cell undergone?

An anther has 1200 pollen grains. How many pollen mother cells must have been there to produce them?

Name the pathological condition when uncontrolled cell division occurs.


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