Join / Login

Give an account of prophase - 1 of meiosis.


The first phase of Meiosis is Prophase I. This phase is more complicated and prolonged as compared to the similar stage of mitosis.

Prophase I is divided into five sub-phases: leptotene, zygotene, pachytene, diplotene and diakinesis. Another sub-phase called pre-leptonema is sometimes recognized prior to leptonema. Chromosomes are not distinguishable because of their thinness. Sex chromosomes are often seen in heterochromatic bodies.
At the start of prophase I, the chromosomes have already duplicated. During prophase I, they coil and become shorter and thicker and visible under the light microscope.
The duplicated homologous chromosomes pair and crossing-over (the physical exchange of chromosome parts) occurs. Crossing-over is the process that can give rise to genetic recombination. At this point, each homologous chromosome pair is visible as a bivalent (tetrad), a tight grouping of two chromosomes, each consisting of two sister chromatids. The sites of crossing-over are seen as crisscrossed non-sister chromatids and are called chiasmata (singular: chiasma).
The nucleolus disappears during prophase I.
In the cytoplasm, the meiotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell.
The nuclear envelope disappears at the end of prophase I, allowing the spindle to enter the nucleus.
Prophase I is the longest phase of meiosis, typically consuming 90% of the time for the two divisions.

Answer verified by Toppr

Upvote (3)
Was this answer helpful?

Related questions

Which is not a stage of mitosis ? 

View solution

Match the column:
(a) Pachytene(i) Pairing of homologous chromosomes 
(b) Metaphase I (ii) Terminalisation of chiasmata
(c) Diakinesis(iii) Cross-over takes place
(d) Zygotene(iv) Chromosomes align at equatorial plate 

View solution

Recombination of genes occur at

View solution

Refer to the following statements describing Prophase I of meiosis and answer the question.
(i) Thin thread like chromosomes with a beaded appearance
(ii) Appearence of recombination nodules
(iii) Formation of bivalents/tetrads
(iv) Terminalisation of chiasmata
(v) Appearance of chiasmata
Arrange the given statements in the correct sequence of their occurrence during prophase I. 

View solution

The chronological sequence of stages in prophase of meiosis is

View solution

The prophase of reduction division is divided into number of stages. The correct chronological sequence is

View solution

Short / Long Answer Type Questions :
Draw and explain a series of diagrams that illustrate the stages of meiosis I.

View solution

During the pachytene stage in crossing over, the exchange of genetic material occurs between

View solution

Study the given diagram and select correct option.

View solution

During meiosis, homologous chromosomes pair with one another. This is known as

View solution
View solution
View solution
View solution
View solution
View solution
View solution
View solution
View solution
View solution
View solution

View more

Create custom Assignments
Customize assignments and download PDF’s
Make now

Learn with content

Watch learning videos, swipe through stories, and browse through concepts

  • Concepts
  • Videos
  • Stories

Take Toppr Scholastic Test for Aptitude and Reasoning

Win exciting scholarships and plan a great education plan