Biology

Molecular Genetics

917 Questions

Molecular genetics explores the mechanisms of genetic information transfer, including DNA replication, transcription, and translation. It is a core component of biology syllabi. These concepts frequently appear in general science sections of major competitive exams.

DNA replicationTranscription processTranslation processRNA typesCentral dogma

Molecular Genetics Questions

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

The nucleus is not important as the site of:

  1. DNA synthesis

  2. RNA synthesis

  3. Synthesis of ribosomal subunits

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

The nucleus is a spherical organelle which is present in eukaryotic cells. The main function of the nucleus is to control gene expressions. It synthesizes RNA and DNA. Protein synthesis takes place in Ribosomes in the cytoplasm

Hence, the correct answer is 'Protein synthesis'.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

The function of polymerase chain reaction (PCR) is

  1. Translation

  2. Transcription

  3. DNA amplification

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

Translation is the process of synthesis of protein using mRNA nucleotide sequence as template, it occurs in cytoplasm. Transcription is the process of mRNA synthesis using DNA coding strand as template, it occurs in nucleus. PCR is a technique to amplify the gene of interest in three steps namely denaturation of target DNA (thermal cycle to separate the DNA strands), annealing of primers to the ssDNA and polymerisation (extension of primer into complete DNA strand complementary to the template strand). After completion of one cycle of PCR, two copies of the target DNA are produced both of which serve as template for next PCR cycle and produce 4 copies. Hence, there is exponential amplification of DNA copies. Correct option is C.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Enzyme required for polymerase chain reaction (PCR) is

  1. RNA polymerase

  2. Ribonuclease

  3. Taq polymerase

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

PCR requires a thermostable DNA polymerase to synthesize new DNA strands during the extension phase. Taq polymerase, isolated from Thermus aquaticus, is the standard enzyme used because it withstands high temperatures.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which of the following is not required in PCR?

  1. DNA primer

  2. DNA template

  3. RNA primer

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

DNA primer is not required for a PCR reaction. 

The reason for RNA primers to be used in PCR is the non availability of DNA primers. The RNA primers complimentary to the cellular DNA are easily synthesized by the DNA Primase enzyme which is nothing but RNA polymerase just like mRNA.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Polymerase chain reaction is used for

  1. In vivo replication

  2. In vivo synthesis of mRNA

  3. In vitro replication of DNA segment

  4. In vitro synthesis of mRNA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

PCR is an in vitro technique used to replicate specific DNA segments outside of a living organism.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

PCR proceeds in three distinct steps governed by temperature. The order of the steps is 

  1. Denaturation, Synthesis, Annealing

  2. Annealing, Synthesis, Denaturation

  3. Synthesis, Annealing, Denaturation

  4. Denaturation, Annealing, Synthesis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The three steps of PCR are: 1) Denaturation (high heat to separate strands), 2) Annealing (cooling to allow primers to bind), and 3) Extension/Synthesis (optimal temperature for polymerase to build the new strand).

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which one of the following enzymes is used in PCR reaction?

  1. Taq polymerase

  2. RNA polymerase

  3. Rib nuclease

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

Taq polymerase is the thermostable enzyme essential for the extension phase of the PCR reaction, allowing it to withstand high temperatures.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which among the following is true for protein synthesis in bacteria?

  1. It involves all the three types of RNAs (m-RNA, t-RNA and r-RNA)
  2. It involves $3$ types of RNA polymerase

  3. It involves single type of RNA polymerase

  4. It involves RNA processing
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In bacteria, transcription is performed by a single type of RNA polymerase that synthesizes all three types of RNA (mRNA, tRNA, and rRNA).

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Select the wrong pair

  1. RNA polymerase I - Sn RNA 5S rRNA, r-RNA

  2. RNA polymerase I - r-RNA

  3. RNA polymerase II - hnRNA

  4. RNA polymerase III - tRNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

RNA polymerase I is responsible for transcribing rRNA (except 5S rRNA). RNA polymerase III transcribes tRNA, 5S rRNA, and snRNA. Option A is incorrect because RNA polymerase I does not transcribe snRNA or 5S rRNA.

Multiple choice zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

"Secondary messenger" is

  1. Cyclic AMP

  2. ATP

  3. ADP

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

Cyclic adenosine monophosphate is a secondary messenger important in many biological processes. It is a derivative of ATP. When a G-protein–coupled receptor on the surface of a cell binds to its particular ligand, the receptor may stimulate the intracellular production of cAMP by the adenylyl cyclase-associated with that receptor. cAMP can then diffuse through the cytoplasm, where it interacts with various targets. Thus, cAMP serves as a second messenger within a cell.

It is used for intracellular signaling system such as transferring into cells the effects of hormones like glucagon and adrenaline, which cannot pass through the plasma membrane. It is also involved in the activation of protein kinases. Hence option A is correct.

Multiple choice botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

A thread like structure in the nucleus of a cell formed of DNA which carries the genes is

  1. DNA

  2. Genes

  3. Chromosomes

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

Deoxyribonucleic acid (DNA) is the information-carrying molecule found in all living organisms. In most animal, plant and fungal cells, DNA is stored in the nucleus coiled up in thread-like structures called chromosomes.

So, the correct answer is option C.

Multiple choice botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

Telomeres

  1. Initiate RNA synthesis

  2. Help chromatids to move towards poles

  3. Seal ends of chromosomes

  4. Identify correct members of homologous pairs of chromosomes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • A telocentric chromosome is a chromosome in which the centromere is located at the terminal end of the chromosome and their shape is similar to the letter i.
  • These chromosomes have a repetitive nucleotide sequence at each end of chromosomes. 
  • It seals and protects each end of the chromosomes from deterioration or fusion with the neighbouring chromosomes during cell division.
  • So, the correct answer is 'Seal ends of chromosomes'.
Multiple choice botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

Mark the correct option w.r.t. chromosomes.

  1. mRNA + ribosomes

  2. mRNA + protein

  3. DNA + Protein

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

The nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.

So, the correct option is 'DNA + protein.

Multiple choice evs identifying the plants absorption of water from the soil root system the root system

Cells of quiescent centre have lower concentration of

  1. DNA

  2. Proteins

  3. RNA

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The quiescent centre is that part of the root-promeristems that contains the initials of epidermis, cortex and stele which divides less frequently and are present at the pole of cortex and stele.
  • In closed meristems, QC is hemispherical in shape whereas, in open meristem it is disc-shaped. 
  • The cells with QC have small dictyosomes, nuclei and nucleoli. 
  • These cells also have little endoplasmic reticulum, mitochondria and contain low concentrations of RNA, DNA and protein than the other cells of the root apex.
  • So, the correct answer is 'All of the above'.