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Molecular Basis of Inheritance

AIPMT 2003MCQMedium📈 Topic in 25% papers+4−1
Ques. 1AIPMT 2003

What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA?

  1. A polypeptide of 49 amino acids will be formed
  2. A polypeptide of 25 amino acids will be formed
  3. Two polypeptides of 24 and 25 amino acids will be formed
  4. A polypeptide of 24 amino acids will be formed

Answer

(4) A polypeptide of 24 amino acids will be formed

Solution

UAU codes for tyrosine, whereas UAA is a stop (nonsense) codon that codes for no amino acid.

⇒ Translation proceeds through codons 1 to 24 and terminates at the 25th codon (UAA).

∴ A polypeptide of only 24 amino acids is formed.

Answer: (4)

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Ques. 2AIPMT 2003

What does "lac" refer to in what we call the lac operon?

  1. The number 1,00,000
  2. Lac insect
  3. Lactase
  4. Lactose
Ques. 3AIPMT 2003

During translation initiation in prokaryotes, a GTP molecule is needed in:

  1. Association of 30S-mRNA with formyl-met-tRNA
  2. Formation of formyl-met-tRNA
  3. Association of 50S subunit of ribosome with initiation complex
  4. Binding of 30S subunit of ribosome with mRNA
Ques. 4AIPMT 2003

Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as 'start' or 'stop' codon?

  1. UUU – Stop
  2. UAC – Tyrosine
  3. UGU – Leucine
  4. UCG – Start
Ques. 5AIPMT 2003

During transcription, the DNA site at which RNA polymerase binds is called:

  1. Receptor
  2. Regulator
  3. Enhancer
  4. Promoter
Ques. 6AIPMT 2003

Degeneracy of a genetic code is attributed to the:

  1. Second member of a codon
  2. Third member of a codon
  3. First member of a codon
  4. Entire codon
Ques. 7AIPMT 2003

In the genetic code dictionary, how many codons are used to code for all the 20 amino acids:

  1. 64
  2. 20
  3. 60
  4. 61
Ques. 8AIPMT 2002

In a DNA percentage of thymine is 20% then what is the percentage of guanine : -

  1. 40%
  2. 20%
  3. 30%
  4. 60%
Ques. 9AIPMT 2002

Transformation experiment was first performed on which bacterium : -

  1. Diplococcus pneumoniae
  2. Pasteurella pestis
  3. E. coli
  4. Salmonella
Ques. 10AIPMT 2002

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
Ques. 11AIPMT 2002

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

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

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