Advertisements
Advertisements
Question
With the help of suitable diagrams, explain the five stages of prophase-I of meiosis.
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
Genetic recombination occurs in ______ phase of prophase of meiosis-I.
Fill in the blank:
______ takes place in body cells resulting in growth and development.
Choose the correct answer:
Nuclear membrane reappears in ____________
The diagram below represents a certain stage of a cell.
(i) Is it an animal cell or a plant cell ? Give one reason in support of your answer.
(ii) Label the parts numbered 1 – 3.
(iii) Which stage (phase) of mitosis is represented in this diagram
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
The stage in mitosis when the nucleolus starts disappearing.
Give Technical Terms
The stage at which spindle fibres begin to be formed.
Give Technical Terms
Division of nucleus.
Complete the following sentence with appropriate word :
Colchicine arrests cell division at __________.
Mention, if the following statement is True or False. If false rewrite the wrong statement in its correct form:
The alkaloid colchicine inhibits the formation of the mitotic spindle.
Multiple Choice Question:
The nuclear membrane and nucleolus become indistinguishable during
The karyotype (set of chromosomes) shown below is taken from a dividing cell in a certain individual.
(i) Is the individual male or female? Explain your answer.
(ii) How would you expect
(a) a female cell and
(b) sperm cell to differ in chromosome composition?
In which stage of mitosis the chromosomes align in an equatorial plate? How?
During Mitosis what is the position of chromatids in the anaphase?
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:
What is the main function of the spindle fibres during mitosis?
