Biology

DNA and Genetics

1,095 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

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

After the biosynthetic phase, the product is separated and purified by the process called as:

  1. Agarose gel electrophoresis

  2. PCR

  3. Downstream processing

  4. Insertional inactivation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
After the biasynthetic, the product is seprated and parified by the process called doren stream processing. It involves $5$ stages.
$(1)$ solid- liquid sepretion
$(2)$ Retrase of intractual products
$(3)$ concentration
$(4)$ Purification by chronatography
$(5)$ Formulation
So, the correct answer is $[C]$ Downstrain processing.
Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

What must be done before placing DNA into the electrophoretic chamber?

  1. It must be ground up with mortar and pestle

  2. It must be cut by restricition endonucleases

  3. It must be treated with RNAase

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is option B i.e. "It must be cut by restriction endonucleases"
Electrophoresis is a method for separation of macro-molecules like DNA. Preparing the DNA for electrophoresis is an important step. DNA is "digested" or cut by restriction enzymes before being run on a gel so that DNA can be separated based on DNA size, fragment and length.

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

Purified DNA ultimately precipitate out after the addition of chilled ethanol. This DNA that separate out can be removed by _____________.

  1. Electrophoresis

  2. Downstream processing

  3. PCR

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

Answer is option D i.e. "Spooling"
At the last step of DNA extraction, purified DNA precipitates out after the addition of chilled ethanol. This DNA appears as collection of fine threads in the suspension which can be spool over the glass rod, this method is called as DNA spooling.

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

Agarose which is extracted from sea weeds is most widely used in

  1. Gel electrophoresis

  2. Spectrophotometry

  3. Tissue culture

  4. PCR
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Agarose is the supporting structure in the cell walls of certain species of algae and which is released on boiling. Agarose is a polysaccharide polymer extracted from seaweed. Slabs of agarose gels are used for electrophoresis.
Thus, the correct answer is option A.

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

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.

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

What is the function of gel electrophoresis in genetic engineering?

  1. Cut DNA into many fragments

  2. Link together newly joined fragments of DNA

  3. Make millions of copies of a specific segment of DNA

  4. Separate fragments of DNA by their length and electrical charges
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gel electrophoresis is a technique used to separate DNA fragments according to their size. DNA samples are loaded into wells (indentations) at one end of a gel, and an electric current is applied to pull them through the gel. DNA fragments are negatively charged, so they move towards the positive electrode. 

So, the correct option is 'Separate fragments of DNA by their length and electrical charges'.

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

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

  1. electrophoresis

  2. restriction mapping

  3. centrigugation

  4. polymerase chain reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gel electrophoresis is a method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge. It is used in molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge.


Nucleic acid molecules are separated by applying an electric field to move the negatively charged molecules through a matrix of agarose or other substances. Shorter molecules move faster and migrate farther than longer ones because shorter molecules migrate more easily through the pores of the gel. This phenomenon is called sieving.

DNA Gel electrophoresis is usually performed for analytical purposes, often after amplification of DNA via polymerase chain reaction (PCR), but may be used as a preparative technique prior to use of other methods such as mass spectrometry, RFLP, PCR, cloning, DNA sequencing, or Southern blotting for further characterization.

So the correct option is 'Electrophoresis'.

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

A mixture containing DNA fragments, A, B, C and D, with molecular weights of A + B = C, A > B and D > C, was subjected to agarose gel electrophoresis. The positions of these fragments from cathode to anode sides of the gel would be 

  1. D, C, A, B

  2. A, B, C, D

  3. C, B, A, D

  4. B, A, D, C.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Shorter lengths of DNA move faster than longer lengths so move further in the time the current is run. So, since D has the heaviest weight (implying it has the longest strand), it will tend to remain far from the anode. B being a lightest fragment moves farthest from the cathode.
  • Hence The positions of these fragments from cathode to anode sides of the gel would be D, C, A, B,
  • So,the correct answer is 'D,C,A,B'.