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प्रश्न
Describe the structure of sex chromosomes with the help of labelled diagram.
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उत्तर
Structure of X and Y chromosomes:
- The x chromosome is straight, rod-like, and longer than the Y chromosome.
- The x chromosome is metacentric, while the Y chromosome is acrocentric.
- The x chromosome has a large amount of euchromatin (extended region) and a small amount of heterochromatin (highly condensed region).
- Euchromatin has a large amount of DNA material, hence the X chromosome is genetically more active.
- The y chromosome has a small amount of euchromatin and a large amount of heterochromatin, hence it is genetically less active or inert.
- Both X and Y chromosomes show homologous and non-homologous regions.
- Homologous regions show similar genes while non-homologous regions show dissimilar genes.
- Crossing over occurs only between homologous regions of X and Y chromosomes.
- The non-homologous region of the X chromosome is longer and contains more genes than that of a non-homologous region of the Y chromosome.
- X-linked genes are present on the non-homologous region of the X-chromosome while Y-linked genes are present on the non-homologous region of the Y-chromosome.
संबंधित प्रश्न
The term “chromosomes” literally means ______.
Correct the following statement if there is any mistake:
If there are 46 chromosomes in a cell, there will be 23 chromatin fibres inside the nucleus during interphase.
Choose the correct answer:
Chromosome is most coiled at (in mitosis) ____________
Choose the correct answer:
Minimum coiling in chromosome is at ________________
Give a reason for the following:
Gametes must be produced by meiosis for sexual reproduction.
Explain the Term Zygotene
Multiple Choice Question:
After mitotic cell division, a female human cell will have
Compare X chromosome and Y chromosome.
With the help of a neat labelled diagram, describe the structure of chromosome.
