Question:

The exchange of segments of non-sister chromatids between chromosomes of a homologous pair is termed as

Updated On: Jan 18, 2023
  • transformation
  • translocation
  • crossing over
  • chromosomal aberration
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The Correct Option is C

Solution and Explanation

During pachytene stage of meiosis-I, the chromosomes become bivalent (tetrad) in the beginning, ie, each chromosome with two chromatids and four arms. Then, non sister chromatids of homologous chromosomes exchange segments between themselves. This exchange of segment is called crossing over. Crossing over is supposed to begin in late pachyteiie and completed in early diplotene.
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Concepts Used:

Meiosis

Meiosis is a process in which a single cell, a diploid cell, undergoes division twice to produce four haploid daughter cells, and the cells produced are known as the sex cells or gametes (sperms in males and egg in females). It contains half of the original amount of genetic information. The haploids only have half the number of chromosomes of the parent cell.

Features of Meiosis:

  • It results in the formation of four daughter cells in each cycle of cell division.
  • The daughter cells are identical to the mother cell in shape and size but different in chromosome number.
  • The daughter cells are haploid.
  • Recombination and segregation take place in meiosis.
  • The process occurs in the reproductive organs and results in the formation of gametes.
  • The process is divided into two types-Meiosis-I reduces the chromosome number to half and is known as reductional division. Meiosis-II is just like the mitotic division.

Phases of Meiosis

Meiosis can be divided into nine stages. The process is usually divided into two parts. The first time a cell divides (meiosis I) and the second time it divides (meiosis II). The phases are as follows –

Meiosis 1 Stages

The different stages of meiosis 1 can be explained by the following phases :

  • Prophase 1
  • Metaphase 1
  • Anaphase 1
  • Telophase 1

Meiosis 2 Stages

The different stages of meiosis 1 can be explained by the following phases :

  • Prophase 2
  • Metaphase 2
  • Anaphase 2
  • Telophase 2