Biology

DNA and Genetics

985 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 botany biotechnology: principles and processes downstream processing biotechnology biotechnology and its application

DNA fragments with sticky ends are not allowed to undergo self ligation by

  1. Unwindase

  2. Single strand binding proteins

  3. Gyrase

  4. Alkaline phosphatase
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The correct option is D.
DNA fragment with sticky end are not allowed to undergo self ligation by Alkaline phosphatase. Alkaline phosphatase is a useful enzyme in genetic engineering, it remove $5'$ phosphase group from DNA and RNA fragments. It also removes the $5'$ phosphase groups from nucleotide and proteins.
Multiple choice botany biotechnology: principles and processes downstream processing biotechnology biotechnology and its application

Read statements a-d. Which of the following statements are incorrect?
a) First transgenic buffalo Rosie produced milk which was human alpha-lactalbumin enriched.
b) Restriction enzymes are used in isolation of DNA from other macromolecules.
c) Downstream processing is one of the steps of rDNA technology.
d) Disarmed pathogen vectors are also used in the transfer of rDNA into the host.

  1. b and c

  2. c and d

  3. a and c

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

Statement (a) is incorrect because Rosie was a cow, not a buffalo. Statement (b) is incorrect because restriction enzymes are used to cut DNA, not for the isolation of DNA from other macromolecules (which is done via chemical extraction).

Multiple choice botany biotechnology: principles and processes downstream processing biotechnology biotechnology and its application

In insertional inactivation of $\beta$-galactosidase gene, the bacteria in white colonies have

  1. Nonrecombinant plasmid

  2. Recombinant plasmid

  3. No plasmid

  4. Linear foreign DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In insertional inactivation, if the foreign DNA is inserted into the beta-galactosidase gene, the gene is disrupted and cannot produce the enzyme. Therefore, colonies containing the recombinant plasmid remain white (do not turn blue).

Multiple choice biotechnology and genetic engineering genetic technology genetic engineering biology making use of enzymes

When using bacteria to clone a human gene and express its product-as in the case of insulin-the gene cannot contain introns because bacteria do not have the enzymes to process mRNA. Therefore

  1. if the sequence is known, very small human genes can be built with a DNA synthesizer in a laboratory and they will lack introns

  2. reverse transcriptase can be used to make DNA backwards from human mature mRNA and this would lack introns

  3. it is impossible to use bacteria to express human gene products because all human genes have introns

  4. both (a) and (b) are true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In order for a human gene to be expressed in bacteria, it must have one important modification. Specifically, it must lack introns. Introns are intervening sequences found in many human genes, and they are removed from eukaryotic RNA transcripts by splicing to make a mature mRNA. Bacteria lack enzymes for splicing. This problem is tackled by using the following approaches:- 

  1. Reverse transcriptase is used to make DNA backwards from human mature mRNA. This DNA will lack introns and DNA will contain only those genes that are going to be expressed. 
  2. Artificial gene synthesis by building polynucleotide chain based on the sequence of nucleotides in DNA fragment of the gene of interest. 

So, the correct option is 'both (a) and (b) are true'. 

Multiple choice biology mendel's law of inheritance mendel's laws laws of inheritance mendel's laws of inheritance

Which of the following is not considered as a law?

  1. Law of dominance

  2. Law of independent assortment

  3. Law of segregation

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The law of dominance is significant and true but is not universally applicable. Only Law of independent assortment and Law of segregation are considered to be laws. The third one is considered as a basic principle but not a genetic law of Mendel. Therefore, (a) is the correct answer.

Multiple choice biology reproduction in animals story of dolly, the clone sheep story of dolly, the clone process of cloning

It is advantageous to use a vector having multiple cloning sites, as it ___________________.

  1. Contains many copies of a cloned gene

  2. Contains many copies of the same restriction enzyme site

  3. Allows flexibility in the choice of restriction enzymes

  4. Allows flexibility in the choice of genes for cloning
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple cloning sites in a cloning vector contain recognition sequences for numerous restriction endonucleases. This provides great flexibility to researchers when choosing which restriction enzymes to use for inserting foreign DNA.

Multiple choice biochemical polymers polymerisation chemistry

The replication of DNA can be catalyzed by:

  1. protein

  2. enzyme

  3. bacteria

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

The replication of $DNA$ can catalyzed by an enzyme. Many enzymes are involved during this process such as DNA helicase, DNA ligase, DNA polymerase etc. Each enzyme has a specific function during replication.

Multiple choice zoology molecular genetics one gene - one enzyme hypothesis component of the cell cell and cell organelles

One gene-one enzyme hypothesis was postulated by

  1. R. Franklin

  2. Hershey and Chase

  3. A. Garrod

  4. Beadle and Tatum
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Beadle and Tatum did classical experiments on Neurospora crassa to prove that in a multistep biochemical pathway, each step is controlled by different enzymes and each of these enzymes are encoded by specific gene. This is called as one gene one enzyme hypothesis
So, the correct answer is 'Beadle and Tatum'
Multiple choice zoology molecular genetics one gene - one enzyme hypothesis component of the cell cell and cell organelles

Beadle and Tatum did classical experiments on Neurospora crassa to prove

  1. One gene produces one enzyme.

  2. One enzyme can correct one gene.

  3. Many genes produce one enzyme.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Beadle and Tatum did classical experiments on Neurospora crassa to prove that in a multistep biochemical pathway, each step is controlled by different enzymes and each of these enzymes are encoded by specific gene. This is called as one gene one enzyme hypothesis. Option A is the correct answer.

Multiple choice zoology molecular genetics one gene - one enzyme hypothesis component of the cell cell and cell organelles

One gene-one enzyme relationship was established for the first time in

  1. Neurospora crassa

  2. Salmonella typhimurium

  3. Polygenic inheritance

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

Beadle and Tatum did classical experiments on Neurospora crassa to prove that in a multistep biochemical pathway, each step is controlled by different enzymes and each of these enzymes are encoded by specific gene. This is called as one gene one enzyme hypothesis. Option A is the correct answer.

Multiple choice zoology molecular genetics one gene - one enzyme hypothesis component of the cell cell and cell organelles

One gene one enzyme concept implies that

  1. One gene controls one enzyme.

  2. All the enzymes are controlled by genes.

  3. All the genes are controlled by enzymes.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One gene one enzyme was given by Beadle & Tatum in which he explains the concept that one gene is capable of producing one enzyme only and is responsible for one individual step in the metabolic pathway.

So, the correct answer is "One gene controls one enzyme".

Multiple choice zoology molecular genetics one gene - one enzyme hypothesis component of the cell cell and cell organelles

The idea that a single gene coded for a polypeptide rather than an enzyme was evident from the

  1. use of X-rays to make nutritional mutants in bread mold

  2. transformation of bacteria from rough and non-virulent to smooth and virulent

  3. presence of a mutation in one chain of hemoglobin but not in the other

  4. discovery that mutated genes changed enzymes in a biochemical pathway
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to one gene-one polypeptide hypothesis, the information enclosed in one gene is sufficient to form one polypeptide only. Genes control the synthesis of all proteins. Some proteins are enzymes and some are hormones. As we know that proteins are made up of polypeptides- long chains of amino acids. Some proteins consist of two or more polypeptides linked and twisted around each other. For eg, hemoglobin.

So, the correct option is presence of a mutation in one chain of hemoglobin but not in other'.