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Cytogenetics Mcqs

Q:

A Lac repressor is a tetramer repressed when bound to the inducer. The trp repressor is a ____________________

A) Dimer inactivated when bound to the inducer B) Dimer activated on inducer binding
C) Tetramer inactivated on inducer binding D) Tetramer activated on inducer binding
 
Answer & Explanation Answer: B) Dimer activated on inducer binding

Explanation: A trp repressor is a dimer which can’t bind to the cis element unless it is bound to the inducer tryptophan. Only then it undergoes conformational change such that it then binds to the operator.

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365
Q:

Epistasis is the interaction between_____________ genes.

A) 2 B) 4
C) 8 D) 16
 
Answer & Explanation Answer: A) 2

Explanation: Epistasis is the interaction between two genes where the genotype of one location affects the expression of genotype at the other location.

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351
Q:

Flow cytometry uses_____________

A) Heavy isotope B) Radioactive elements
C) Immunological techniques D) Energy content
 
Answer & Explanation Answer: C) Immunological techniques

Explanation: The process of flow cytometry is based on immune fluorescence where a laser is used to irradiate the fluorescent particle bound to a particle that determines its fete.

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190
Q:

Capping of RNA is necessary as_______

A) It helps us distinguish 5’ from 3’ end B) It has a rolling action and condenses the transcript as it is produced
C) To protect the transcript from exonuclease D) To prevent the transcript from sticking to DNA
 
Answer & Explanation Answer: C) To protect the transcript from exonuclease

Explanation: Not available for this question

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185
Q:

Which of these systems give the best mode for turning trp operon off?

A) Repressor B) Attenuator
C) Repressor with a downstream poly A tail D) Repressor with an attenuator
 
Answer & Explanation Answer: D) Repressor with an attenuator

Explanation: A repressor provides 70 fold lowering of expression while an attenuator provided an additional 10 fold lowering of expression. Together they have a net effect of 700 fold repression over the trp operon.

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177
Q:

Self crossing a white flower of sweet pea would give a ____________________

A) White flower only B) Equal probability of white or purple
C) More white flower than purple D) Purple flowers only
 
Answer & Explanation Answer: A) White flower only

Explanation: The white flower arises due to a homozygous recessive condition in atleast one of the two gene locus. In this case self crossing can never yield a combination of heterozygous or homozygous dominant at that gene locus, so it will only give white flowers.

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166
Q:

If an organism has 14 chromosomes, the number of chromosome generated by nullisomy will be_____________________

A) 15 B) 7
C) 13 D) 12
 
Answer & Explanation Answer: D) 12

Explanation: Nullisomy results in (2n-2) set of chromosome, here n=7, so it will result in 12 chromosome over all.

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162
Q:

Differential expression of the genetic material depending on its parentage of inheritance gives____________

A) Penetrance B) Expressivity
C) Imprinting D) Non-penetrance
 
Answer & Explanation Answer: C) Imprinting

Explanation: Genomic imprinting states that the alleles of some genes vary in their or expression depending on the fact that they are inherited from the mother or the father.

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