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प्रश्न
Can there be DNA replication without cell division?
उत्तर
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.
- 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.
- 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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संबंधित प्रश्न
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 ______.
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.
In which of the following phase of mitosis chromosomes are arranged at the equatorial plane?
Choose the correct option.
Histone proteins are synthesized during ______.
Match the following column A with column B.
| Column-A (phases) |
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 ______.
The paring of homologous chromosomes on meiosis is known as ______.
Differentiate cytokinesis in plant cells and animal cells.
Write about Pachytene of Prophase I.
Write about Pachytene and Diplotene of Prophase I
Name the pathological condition when uncontrolled cell division occurs.
