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प्रश्न
With the help of suitable diagrams, explain the five stages of prophase-I of meiosis.
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उत्तर
Prophase-I is the first stage of meiosis-I and is the longest and most important stage. It is divided into five sub-stages:
1. Leptotene
- Chromosomes begin to condense.
- They become long, thin, and distinct.
2. Zygotene
- Homologous chromosomes pair together by a process called synapsis.
- A synaptonemal complex is formed.
- Paired chromosomes form bivalents or tetrads.
3. Pachytene
- It is the longest stage of Prophase-I.
- Chromosomes become shorter and thicker.
- Crossing over occurs between non-sister chromatids of homologous chromosomes.
- Recombination nodules appear at crossing-over sites
4. Diplotene
- Synaptonemal complex dissolves.
- Homologous chromosomes begin to separate.
- Chiasmata appear at crossover points.
5. Diakinesis
- Chiasmata terminalise.
- Chromosomes condense further.
- The nuclear membrane and nucleolus disappear.
- Meiotic spindle fibres begin to form.
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संबंधित प्रश्न
Genetic recombination occurs in ______ phase of prophase of meiosis-I.
Fill in the blank:
______ is the indirect cell division.
The fig given alongside shows a certain stage in a cell division in a cell with four chromosomes.
(i) Name the parts of the chromosome labeled A and B.
(ii) Name the structure C. what is its function?
(iii) Name the type of division . Give a reason.
(iv) Name the stage of division.
(v) Name the stages before and after the stage shown in diagram.
In which one of the following options the two stages of mitosis have been given in correct sequence?
Identify the stages of mitosis given below and label the figures.
Draw a labeled schematic representation of mitosis cell division.
Name the following:
Replacement of dead cells is accomplished by which process.
Name the Following
The stage when chromosomes arrange at the equator.
Name the Following
Name the stage during which nuclear membrane and nucleoli reappear.
Name the Following
Nuclear envelope and nucleoli reappear in which stage.
Give Technical Terms
Division of nucleus.
Multiple Choice Question:
The nuclear membrane disappears in
Write the functional activity of the following structure:
Colchicine
Column ‘II’ is a list of items related to ideas in Column ‘I’. Match the terms in Column ‘II’ with a suitable idea given in Column ‘I’.
| Column I | Column II |
| (i) Anaphase | (a) Chromosomes become arranged in a horizontal plane at the equator. |
| (ii) Prophase | (b) Daughter chromosomes move to opposite poles of the spindle. |
| (iii) Telophase | (c) Chromosomes become visible as fine, long threads. |
| (iv) Metaphase | (d) Chromosomes lose their distinctiveness and gradually become transformed into chromatin network. |
Give the sequence of the events occurring during the prophase of mitosis.
During Mitosis what is the position of chromatids in metaphase?
During Mitosis what is the position of chromatids in the anaphase?
The phase of karyokinesis which is almost the reverse of prophase is ______.
Match List - I with List - II.
| List - I | List - II |
| A. Centromere | I. Mitochondrion |
| B. Cilium | II. Cell division |
| C. Cristae | III. Сell movement |
| D. Cell membrane | IV. Phospholipid Bilayer |
Choose the correct answer from the options given below:
