Tag: biochemical techniques

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Questions Related to biochemical techniques

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

Escherichia coli, in which both the strands of DNA are labeled  with $^{15}N$ is transferred to $^{14}N$ medium and allowed to replicate for three generations. Find out the number of hybrid DNA molecules in the third generation

  1. 8

  2. 2

  3. 12

  4. 10
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In semi-conservative replication, the two original strands (15N) separate. After one generation, all DNA is hybrid (15N-14N). After two generations, there are 2 hybrid and 2 light (14N-14N) molecules. After three generations, there are 8 total molecules, but only 2 remain hybrid (the original strands are always part of a hybrid molecule).

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

Fragments of DNA formed after treatment with endonucleases are separated by the technique

  1. Polymerase chain reaction

  2. Southern blotting

  3. Colony hybridisation

  4. Electrophoresis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gel electrophoresis is the standard laboratory technique used to separate DNA fragments based on their size and charge after they have been cut by restriction endonucleases.

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

First step in Southern blot technique is

  1. Digestion of DNA by restriction enzyme

  2. Production of a group of genetically identical cells

  3. Denaturation of DNA on the gel for hybridisation with specific probe

  4. Denaturation of DNA from a nucleated cell as from the scene of crime
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The first step in a Southern blot technique is to prepare the DNA mixture by breaking it into smaller fragments using a restriction enzyme.