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Molecular Basis of Inheritance · Question 152

AIPMT 2002MCQMedium📈 Topic in 88% papers+4−1
1

Jacob and Monod studied lactose metabolism in E. coli and proposed operon concept. Operon concept is applicable for :

  1. All prokaryotes and all eukaryotes
  2. All prokaryotes and some protozoans
  3. All prokaryotes
  4. All prokaryotes and some eukaryotes

Answer

(4) All prokaryotes and some eukaryotes

Solution

As per NCERT, the lac operon of E. coli (a regulator gene, a promoter, an operator and the structural genes z, y and a) explains the regulation of gene expression in prokaryotes.

An operon is a group of genes for one metabolic pathway that are transcribed together as one polycistronic mRNA under the control of a single promoter and operator.

∵ In prokaryotes, genes are commonly organised into operons ⇒ the operon concept applies to all prokaryotes.

∵ In eukaryotes, genes are usually monocistronic and gene regulation is more complex (at transcriptional, processing, transport and translational levels) ⇒ operons are not the general rule.

However, a few operon-like gene clusters transcribed together are known in some eukaryotes (e.g., the nematode Caenorhabditis elegans).

∴ The operon concept is applicable for all prokaryotes and some eukaryotes.

Answer: (4)

AIPMT 2002

Keep practising — Molecular Basis of Inheritance

2

In E. coli, during lactose metabolism repressor binds to : -

  1. Promoter gene
  2. Operator gene
  3. Structural gene
  4. Regulator gene
AIPMT 2002
3

Out of 64 codons, 61 codons code for 20 types of amino acids; it is called : -

  1. Wobbling of codon
  2. Universality of codons
  3. Overlapping of gene
  4. Degeneracy of genetic code
AIPMT 2002
4

Which of the following reunites the exon segments after RNA splicing ?

  1. RNA polymerase
  2. RNA proteases
  3. RNA primase
  4. RNA ligase
AIPMT 2002
5

Exon parts of mRNA have code for : -

  1. Lipid
  2. Protein
  3. Phospholipid
  4. Carbohydrate
AIPMT 2002
6

m-RNA is synthesised on DNA template in which direction : -

  1. Any
  2. Both (3) and (4)
  3. 5' → 3'
  4. 3' → 5'
AIPMT 2001
7

In Negative operon : -

  1. cAMP has negative effect on lac operon
  2. Co-repressor binds with inducer
  3. Co-repressor binds with repressor
  4. Co-repressor does not bind with repressor
AIPMT 2001
8

Gene and cistron words are sometimes used synonymously because : -

  1. One gene contains one cistron
  2. One cistron contains many genes
  3. One gene contains no cistron
  4. One gene contains many cistrons
AIPMT 2001
9

Types of RNA polymerase required in nucleus for RNA synthesis : -

  1. 2
  2. 3
  3. 1
  4. 4
AIPMT 2001
10

A mutant strain of T4 bacteriophage, R-II, fails to lyse E. coli, but when two strains R-IIX and R-IIY are mixed, they lyse E. coli. What may be the possible reason?

  1. Both strains have different cistrons
  2. Both strains have similar cistrons
  3. It is not mutated
  4. Bacteriophage transforms into wild type
AIPMT 2001
11

Method of DNA replication in which two strands of DNA separate and synthesize new strands

  1. Conservative
  2. Non conservative
  3. Dispersive
  4. Semiconservative
AIPMT 2000

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