Division of Genetics
ICAR-Indian Agricultural Research Institute
Mid Term Examination
Principles of Cytogenetics (GP: 502) (2+1)
Roll No.: …………….. Marks: 30
Q1. Fill in the blanks (5 marks)
a. Idiogram consists of ……………………… set of chromosomes ordered in series of …………………. size.
b. Heterochromatin can be distinguished from euchromatin at …………………… stage of meiosis.
c. General chromosome model proposed by ………………………
d. In case of Drosophila, the 4 pairs of chromosomes are united by their centromeric region to form ...................................
e. Somatic synapsis in interphase can be observed in case of .....................................
f. Schizosaccharomyces pombe has ............................... chromosome.
g. Histone proteins are basic in nature because they contain 20–30% of .................... & .......................
h. Telomeres are stabilized by the formation of ......................
Q2. Write short notes on the following (20 marks)
a) Chiasmata theory of crossing over
b) Chromosomal theory of inheritance
c) Diagrammatically illustrate the variation of amount of DNA content through different stages of life cycle (meiosis)
d) Diagrammatically prove that recombination frequency can’t exceed 50%
e) C-mitosis (colchicine mitosis)
f) Synaptonemal complex
g) C value and its paradox
h) Telomerase
i) B chromosomes
j) Detailed structure of centromere
Q3.
Briefly explain the three levels of packaging in nucleosome solenoid model with suitable diagram
(5 marks)
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