Tag: bio-chemistry

Quizzes (82) Questions (1918)

Questions Related to bio-chemistry

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.

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

In gel electrophoresis, differential mobility of DNA depends upon

  1. Helical nature of DNA

  2. Double stranded nature of DNA

  3. Charge and size of DNA

  4. Hydrogen bonding between bases
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DNA is negatively charged due to its phosphate backbone, so it moves toward the anode. The gel matrix acts as a sieve, where smaller fragments move more easily than larger ones, meaning separation depends on both charge and size.

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

The term southern blotting refers to

  1. Transfer of DNA fragments from in vitro cellulose membrane to electrophoretic gel

  2. Attachment of probes to DNA fragments

  3. Transfer of DNA fragments from electrophoretic gel to nitrocellulose sheet

  4. Comparison of DNA fragments from two sources
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Southern blotting is a laboratory technique used to detect specific DNA sequences in DNA samples. It involves transferring separated DNA fragments from an agarose gel to a nitrocellulose or nylon membrane for hybridization probing.

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

A correct pair of characteristics of molecular probe are:
a. Very long molecule
b. Double stranded
c. DNA or RNA
d. Complementary to a part of desired gene.

  1. a,b

  2. b,c

  3. c,d

  4. d,a
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A molecular probe is a single-stranded DNA or RNA molecule that is complementary to the target sequence of interest, allowing it to bind specifically to that sequence.

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

DNA fragments generated by restriction endonucleases in a chemical reaction can be separated by

  1. Restriction mapping

  2. Centrifugation

  3. Polymerase chain reaction

  4. Agarose gel electrophoresis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Agarose gel electrophoresis is the standard technique used to separate DNA fragments of varying lengths generated by restriction endonuclease digestion.