DNA, RNA & Protein Synthesis MCQ Quiz - Objective Question with Answer for DNA, RNA & Protein Synthesis - Download Free PDF

The correct answer is option 3.

Key Points

• Human insulin was the first hormone to be produced using recombinant DNA technology. Hence, option 3 is correct.
• It was developed by Genentech and Eli Lilly in the early 1980s, marking a major breakthrough in biotechnology and medicine.
• This synthetic insulin is called "Humulin", and it is produced by inserting the human insulin gene into E. coli bacteria, which then synthesize insulin.

The Correct answer is mRNA.

Key Points

• mRNA stands for messenger RNA.
• It is responsible for transporting genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs.
• During the process of transcription, DNA is used as a template to produce mRNA.
• The sequence of nucleotides in mRNA corresponds to the sequence of amino acids in a protein, following the rules of the genetic code.
• mRNA carries codons, which are specific sequences of three nucleotides that code for a particular amino acid.
• It plays a crucial role in the process of translation, where ribosomes decode the mRNA to synthesize proteins.
• mRNA has a short life span in the cell, as it is degraded after the protein synthesis process is complete.
• Its primary role is to act as an intermediary between the genetic material (DNA) and the machinery responsible for protein production.

 Additional Information

• tRNA
  • tRNA stands for transfer RNA.
  • It plays a role in translation by bringing specific amino acids to the ribosome based on the codons in the mRNA.
  • Each tRNA has an anticodon that pairs with a complementary codon on the mRNA.
• snRNA
  • snRNA stands for small nuclear RNA.
  • It is primarily involved in the process of splicing during the maturation of pre-mRNA in the nucleus.
  • snRNAs are a component of spliceosomes, which remove introns from pre-mRNA.
• rRNA
  • rRNA stands for ribosomal RNA.
  • It is a structural and functional component of ribosomes, which are the sites of protein synthesis.
  • rRNA helps to catalyze the formation of peptide bonds between amino acids during translation.

The correct answer is RNA polymerase.

Key Points

• Transcription is the formation of mRNA from DNA.
• It occurs inside the nucleus.
• It uses DNA as a template.
• RNA polymerase is necessary for the transcription of mRNA.
• It consists of five subunits which are alpha, beta, beta prime, and omega and sigma.
• The Sigma factor is essential as it recognizes the transcription start site.

Additional InformationDNA polymerase:

• It is essential for replication.
• It occurs inside the nucleus.
• Replication is semiconservative in nature.

Reverse transcriptase:

• It is present inside the virus.
• It forms cDNA(complementary DNA) from mRNA.

Taq polymerase:

• It is isolated from the bacteria Thermus.
• It is used in a polymerase chain reaction to amplify the DNA strands.

Below is the diagram of RNA polymerase

The term ‘allele’ comes from ‘allelomorph’ and refers to the different forms of a gene that affect an organism's phenotype or appearance.

Key Points

• The number of allelic forms of a gene may be many in a population, but since each organism has only one pair of homologous chromosomes of a kind, only two of its variants are present in an organism.
• Various interactions may occur between alleles of the same genes or alleles of different genes, which give rise to different phenotypes, making the inheritance patterns complex.
  • Recessive allele - The allele which is masked or remains unexpressed is called recessive. 
  • Dominant Allele - The allele that completely masks the expression of other alleles is dominant.
  • Codominance- It is a phenomenon in which both the alleles are completely expressed in the heterozygous condition, the phenotype of the heterozygous individual is a mixture of both.
• A combination of different types of alleles influences the inheritance pattern in an individual organism.

Hence, the allele is a pair of genes that occupy a specific location on a particular chromosome and control the same trait.

Important Points

• Karyotype - It is an individual’s complete set of chromosomes or laboratory-produced image of a person’s chromosomes isolated from an individual cell and arranged in numerical order that is used to look for abnormalities in chromosome number or structure.
• RNA - It refers to the Ribo-nucleic acid present in the cells of organisms having a structure similar to DNA.
• Autosomes - The 22 pairs of non-sex chromosomes present in the nucleus of an individual.

The Correct answer is chromosomes.

Key Points

• Chromosomes are thread-like structures made up of DNA and associated proteins found in the nucleus of most living cells.
• They carry genetic information in the form of genes, which determine the characteristics of an organism.
• Each chromosome contains a tightly packed DNA molecule, which is organized into functional units called genes.
• Genes are responsible for controlling heredity and traits like eye color, height, and certain diseases.
• In humans, there are 46 chromosomes (23 pairs), with one set inherited from each parent.
• Chromosomes are visible under a microscope during the cell division process (mitosis and meiosis).
• The DNA within chromosomes carries instructions for the development, functioning, growth, and reproduction of all living organisms and many viruses.
• The study of chromosomes and genes is crucial in the field of genetics and has numerous applications in medicine, agriculture, and evolutionary biology.

 Additional Information

• Vacuoles
  • Vacuoles are membrane-bound organelles found in both plant and animal cells, but they are much larger in plants.
  • In plant cells, vacuoles help in storing water, nutrients, and waste products and play a role in maintaining turgor pressure to provide structural support.
  • In animal cells, vacuoles are smaller and are involved in processes like endocytosis and exocytosis.
• Endoplasmic Reticulum (ER)
  • The endoplasmic reticulum (ER) is a network of membrane-bound tubules and sacs in the cytoplasm of eukaryotic cells.
  • It is divided into two types: rough ER (studded with ribosomes) and smooth ER (lacking ribosomes).
  • The rough ER is involved in protein synthesis, while the smooth ER plays a role in lipid synthesis, detoxification, and calcium storage.
• Lysosome
  • Lysosomes are membrane-bound organelles containing digestive enzymes.
  • They are responsible for breaking down cellular waste, damaged organelles, and macromolecules, a process known as autophagy.
  • Lysosomes are often referred to as the "suicidal bags" of the cell because they can digest the cell itself under certain conditions.

The correct answer is 

Key Points

• A nucleotide is the basic building block of nucleic acids, such as DNA and RNA.
• Each nucleotide in DNA consists of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases:
  • Adenine (A)
  • Guanine (G)
  • Cytosine (C)
  • Thymine (T)
• Polynucleotides are long chains of these nucleotides.

Additional Information

• The backbone of a DNA is made up of repeating units of deoxyribose sugar, nitrogenous base and phosphate group which occur alternately.
• The phosphate group attaches to the -OH group at the 5' carbon of the deoxyribose sugar through a phosphodiester linkage.

Correct answer: 1)

Concept:

• The synthesis of protein is known as translation.
• It takes place in the cytoplasm of the cell.
• The machinery for translation includes- transfer RNA (tRNA), messenger RNA (RNA), ribosomal RNA (rRNA), and different enzymatic factors.

Explanation:

• Option 1: Small interfering RNA (siRNA) are double-stranded RNA molecules that inhibit the translation of specific mRNA.
• They do not participate in protein synthesis.
• Option 2: DNA is transcribed into mRNA that serves as a template for protein synthesis.
• It is single-stranded and contains a sequence of nucleotides that codes for amino acids.
• A triplet of nucleotide forms a codon and each codon codes for a single amino acid.
• Option 3:
• Transfer RNA (tRNA) brings amino acids to the ribosomes during protein synthesis.
• Specific tRNA is there for specific amino acids.
• Option 4: Ribosomes are made up of rRNA which is essential for protein synthesis.

So, the correct answer is option 1. 

• Proteins are made up of Amino Acids, essentially they are the building blocks of proteins.
• Each protein is made from a combination of different amino acids
• There are about 21 amino acids in total.
• Each acid is made up of carbon, hydrogen, oxygen and nitrogen although other elements might also be present in different acids.

Additional Information 

The correct option is 3 that is gene mapping.

Concept:

Animal and plant cell nuclei contain thread-like structures called chromosomes. Deoxyribonucleic acid (DNA), which is transmitted from parents to children during reproduction, is only one of the two components of each chromosome.

The precise instructions that give each sort of living thing its individuality are found in DNA.

Explanation:

• A method for locating a gene's locus and measuring the distances between genes is called gene mapping.
• Gene mapping is used to identify the linear arrangement of genes and how far apart they are from one another on the same chromosome.
• The terms "genome walking" and "chromosome walking" are used to locate unknown DNA sequences next to recognized sequences, although they have nothing to do with locating genes on chromosomes.

• Genes are the units located in the chromosomes of a cell.
• It is a unit of DNA on a chromosome which governs the synthesis of one protein that controls specific characteristics of an organism.
• Genes are composed of deoxyribonucleic acid (DNA), except in some viruses, which have genes consisting of ribonucleic acid (RNA).
• Every human cell contains 23 pairs of chromosomes, for a total of 46 chromosomes.
• Lysosomes are also known as suicidal bags.

• Histones are a set of positively charged, basic proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes.
• A protein acquires charge depending upon the abundance of amino acids residues with charged side chains.
• Histones are rich in the basic amino acid residues lysines and arginines. Both the amino acid residues carry positive charges in their side chains.
• Histones are organized to form a unit of eight molecules called Histone octamer.

​Extra Information :

• Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA) are the two types of nucleic acids found in living systems.
• DNA acts as the genetic material in most of the organisms.
• RNA though it also acts as genetic material in some viruses, mostly functions as a messenger.

The correct answer is a, b, and d.

Concept:

DNA replication

• DNA replication occurs in all living organisms.
• It is an important biological process for inheritance.
• It is an enzyme-catalyzed reaction.
• The main enzyme in the DNA replication process is DNA Polymerase.
• A DNA molecule replicates itself to create two identical copies.

Explanation:

DNA replication is a semi-conservative process (correct)

• Watson and Crick in 1953 proposed a scheme that DNA replication was semi-conservative.
• Replication is semi-conservative because the two parental strands separate and each strand acts as a template for synthesizing a complementary strand over it.
• After completion of replication, each DNA had one parental strand and one newly synthesized strand.

DNA replication is a semi-discontinuous process (correct)

• DNA replication is a semi-discontinuous process because two complementary strands are synthesized during replication and run anti-parallel. 
• The DNA polymerase can only add nucleotides to the 3' end of a DNA strand.
• As a result, one strand is synthesized continuously, known as the leading strand, and the other is synthesized discontinuously, known as the lagging strand.

DNA polymerase III is responsible for the replacement of the primer sequence of the Okazaki fragments (incorrect)

• DNA polymerase III synthesizes a new DNA strand in 5'→3' direction, antiparallel to the template strand.
• DNA polymerase I remove RNA primer nucleotides with its  5'→3' exonuclease activity and replaces them with complementary DNA nucleotides by its 5'→3' polymerisation activity.

Primer is synthesized on both the strands of the DNA (correct)

• Before DNA replication can occur, a primer must be synthesized by an enzyme called primase, which is a type of RNA polymerase. 
• Because the enzymes that synthesize DNA, known as DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides, the synthesis of a primer is required.

Concept-

• Ribosomal RNA or rRNA molecules are synthesized in a specialized region of the cell nucleus called the nucleolus, which appears as a dense region within the nucleus and contains genes encoding rRNA.

Key Points

• Ribosomal RNA (rRNA) is a molecule in cells that is part of protein-building organelles called ribosomes and is exported to the cytoplasm to help translate the information contained in messenger RNA (mRNA) to proteins. 
• The encoded rRNAs are of different sizes, differentiated into large or small. Each ribosome contains at least 1 large rRNA and at least 1 small rRNA. 
• In the nucleolus, large and small rRNAs combine with ribosomal proteins to form large and small ribosomal subunits (eg, 50S and 30S in bacteria, respectively).
• These subunits are usually named for their settling rate, measured in Svedberg [S] units, in the centrifugal field.
• Ribosomal proteins are synthesized in the cytoplasm and transported to the nucleus to be reassembled in the nucleus.
• The subunits are then returned to the cytoplasm for final assembly.
• Prokaryotes have 70S ribosomes that has 50S and 30S subunits, while eukaryotes have 80S ribosome which has a 60S and a 40S subunit.

Additional Information

Protein

• These are the products formed from the genetic information present in a cell.
• They help in carrying out the various metabolic activities of the cell to sustain life.
• mRNA is converted into a protein by the process of translation.

Messenger RNA

• ​This type of RNA functions by transferring the genetic material into the ribosomes and passing the instructions about the type of proteins, required by the body cells.
• We can also say Information from the nucleus to the cytoplasm is carried by m-RNA.
• Based on the functions, this type of RNA is called messenger RNA.
• Therefore, the mRNA plays a vital role in the process of transcription or during the protein synthesis process.

Transfer RNA

• These are RNA molecules that transfers amino acids to the ribosome complex during protein synthesis process.
• Each tRNA carries an amino acid at one end and has an anticodon sequence at another end, which can bind to its complementary sequence on the mRNA.
• Thus tRNAs are adapter molecules that help in reading the genetic code on the mRNA and accordingly add amino acid to the growing peptide chain.
• These are specific for each amino acid.