Principles of Cytogenetics GPB-502 (Question Paper )

  

 

I. Answer the following (1.0 marks each)

1. Diplotene
2. Interphase
3. Synaptonemal complex
4. Pachytene
5. Translocation

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II. Differentiate (2.0 marks each)

1. Prophase of mitosis and Prophase-II of meiosis.
2. Auto-orientation and Co-orientation.
3. Paranemic coiling and Plectonemic coiling.
4. Apogamy and Diplospory.
5. Pericentric and Paracentric inversion.

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III. Answer the following (3.0 marks each)

1. Taking 2n = 6, draw all stages of meiosis.
2. Explain microsporogenesis and microgametogenesis.
3. Explain with diagram the nucleosome solenoid model to explain the structure of chromosome.

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Answer the following (5.0 marks each)

• Taking an example of AB.CDEFGH on a pair of chromosome, if paracentric inversion heterozygote occurs between DEF genes and crossing over takes place between D & E genes, draw and show gametes formed after meiosis. What is the genetic significance?
• If reverse tandem duplication occurs between ABCD genes from a chromosome pair ABCDE.FGHI, draw and show how chromosomes pairing takes place and if crossing over occurs between B and C genes, what are the gametes formed after meiosis.
• Taking 2n = 6, draw meiotic configuration of primary, secondary and tertiary trisomics. What is the genetic significance of trisomics?