Explore topic-wise InterviewSolutions in .

Right OPTION is (d) gene silencing

The EXPLANATION: Micro RNAs (mi RNAs) are processed from the same machinery as SMALL interfering RNAs (siRNAs) and play a role in posttranscriptional RNA silencing pathways.

Right choice is (a) SVEDBERG’s units

For EXPLANATION: “S” STANDS for Svedbergs, a measure of how fast the molecule moves in a centrifuge. The rate of sedimentation is related to the SHAPE and size of the molecule.

Correct OPTION is (C) 3

To elaborate: The synthesis of POLYPEPTIDES, termed as translation, involves 3 distinct ACTIVITIES: initiation of the chain, elongation of the chain, and termination of the chain.

The correct choice is (c) 73-93

To EXPLAIN I would say: All the transfer RNA molecules are ROUGHLY the same length i.e. between 73 to 93 nucleotides. All the tRNAs also have a SIGNIFICANT percentage of posttranscriptionally modified bases.

The correct choice is (b) RNA polymerase II

The explanation is: All eukaryotic mRNA PRECURSORS are synthesized by RNA polymerase II, it is conserved from yeast to MAMMALS.

Right OPTION is (C) 2000

Best explanation: The FIRST structures of ribosomal subunits were made in the year 2000 by scientists Venkatraman Ramakrishnan, THOMAS A. Steitz and Ada E. Yonath, which is available in the Protein DATA Bank.

Correct OPTION is (a) HNRNA

Easiest EXPLANATION: Heterogeneous NUCLEAR RNA (hnRNA) has the SMALLEST half, it is processed into mRNAs shortly after or even during synthesis.

Right option is (b) RNA polymerases

To ELABORATE: RNA polymerases or DNA-dependent RNA polymerases are the enzymes RESPONSIBLE for transcription in both eukaryotes and PROKARYOTES.

Right answer is (a) George Gamow

For explanation I would say: George Gamow proposed that a group of three NUCLEOTIDES, called codons, are responsible for encoding an AMINO acid in the polypeptide chain. The PROCESS of PROTEIN synthesis is REFERRED to as translation.

Correct answer is (a) mRNA

The BEST explanation: Messenger RNA (mRNA) is the intermediate between a GENE and its polypeptide, discovered in 1961. The other types of RNA PLAY DIVERSE roles in a cell.

Correct choice is (a) MRNA

The explanation: Transfer RNAs have the ROLE of decoding the information present in the messenger RNA MOLECULE (mRNA) and direct the ASSEMBLY of amino acids on a polypeptide CHAIN.

The correct answer is (C) pre-tRNA

The explanation: Ribobuclease P is an endonuclease present both in eukaryotes and prokaryotes. It is involved in the processing of pre-tRNA. TRANSFER RNA is synthesized from the processed PRIMARY transcript.

The CORRECT ANSWER is (b) site on DNA

Easiest explanation: Promoter is sequence on the DNA which is the site of binding for RNA polymerase, prior to INITIATION of transcription.

Right ANSWER is (B) siRNA

For explanation: Dicer is a type of RIBONUCLEASE that FRAGMENTS double-stranded RNAs into smaller fragments called SMALL interfering RNAs (siRNA).

The correct option is (b) Francis Crick

Explanation: The degeneracy of codon was predicted by Francis Crick, he considered the great range in base composition of various BACTERIA. The G + C CONTENT of the genomes varied from 20 to 74 PERCENT, whereas the AMINO acid composition of the proteins from these organisms showed little VARIATION.

Right option is (a) True

To explain: The genetic code is DEGENERATE because one amino acid can be ENCODED by more than one CODON. A codon is a group of three nucleotides and amino acid is a CONSTITUENT of the POLYPEPTIDE chain.

The correct answer is (b) piRNAs

Explanation: Piwi-interacting RNAs (piRNAs) are a distinct CLASS of RNA molecules that PREVENT the movement of transposable elements in the GERM cells. These RNAs associate with PIWI PROTEINS, a subclass of ARGONAUTE family.

The correct OPTION is (a) OVALBUMIN

To EXPLAIN I would say: The gene that codes for the white of a chicken is ovalbumin. The promoter of this gene is located between 24 and 32 BASES upstream in the region CALLED TATA box.

Right answer is (c) tDNA

To explain I would SAY: CLUSTERS of tDNA located WITHIN the GENOME are responsible for the transcription of transfer RNAs. Transfer RNAs primarily function in the translation of proteins.

Right ANSWER is (b) 2

Explanation: Two types of post-translational modifications are characteristic of pre-rRNA, large number of methylated nucleotides and pseudouridine RESIDUES. These MAKE the pre-rRNA peculiar and contrasting from other PRIMARY RNA TRANSCRIPTS.

The CORRECT choice is (c) Promoter sequence

The best I can explain: In addition to being a binding SITE for RNA POLYMERASE, promoter sequences contain the information that DETERMINES which of the two strands is transcribed and the site where transcription is initiated.

The correct option is (b) b

To explain: The greatest VARIABILITY among the DIVERSE transfer RNA molecules OCCURS in the variability ARM. It is 4 to 21 nucleotides in LENGTH, located amidst the T-arm and anticodon.

Right answer is (a) poly(U)

EASY explanation: First artificial genetic message was synthesized by Marshall Nirenberg and Heinrich Matthaei, composed of uridine residues CALLED poly(U). They were able to synthesize BACTERIAL proteins using the poly(U), ribosomes, amino ACIDS and soluble FACTORS.

Right CHOICE is (a) METHIONINE

The explanation: The INITIATION codon AUG, CODES for the AMINO acid methionine. It is the first amino acid to be incorporated at the N-terminus of a nascent polypeptide, in bacteria it is formylmethionine.

Right choice is (b) SOLUBLE proteins

Easiest explanation: Initiation FACTORS are the soluble proteins that help in initiating the polypeptide chain formation. Bacterial CELLS have three initiation factors IF1, IF2, and IF3.

The correct choice is (b) mRNA

To elaborate: The Shine-Dalgarno sequence is present 5-10 NUCLEOTIDES upstream of the initiation CODON in the bacterial mRNA. The 16S ribosomal RNA has a COMPLEMENTARY sequence for it which leads to the binding of 30S SMALL ribosomal SUBUNIT on the mRNA strand.

The correct answer is (a) True

For explanation I would say: All mature transfer RNA molecules have the CHARACTERISTIC trinucleotide SEQUENCE CCA at their 3’ end. This sequence is ENCODED in the tRNA gene in prokaryotes while it is added enzymatically in EUKARYOTES.

Correct choice is (c) synonymous

To elaborate: Changes in the genome occur throughout the evolution and among all the species. A change in the nucleotide SEQUENCE of the GENE that does not affect the amino acid sequence of the POLYPEPTIDE is CALLED a synonymous change.

Right choice is (b) False

For explanation I WOULD say: After transcription of the gene, i.e. production of a MESSENGER RNA from the DNA SEQUENCE of the gene, the gene stays in place stored away as GENETIC information.

Right answer is (a) 3

To EXPLAIN I would say: There are 64 possible codons because each CODON consists of 3 NUCLEOTIDES and there are 4 types of nucleotides. Out of the 64 codons, 3 have a special FUNCTION of being termination codons.

The correct option is (a) nucleoli

The BEST I can EXPLAIN: In a non-dividing cell (the cell which is in interphase), the clusters of rDNA come together to form IRREGULARLY shaped nuclear STRUCTURES called nucleolus (plural nucleoli). The nucleoli are dense with primary RNA transcripts.

Correct option is (a) rRNA

Explanation: Ribosomal RNA (rRNA) plays a role in structural SUPPORT and catalyzes the reaction in which amino ACIDS are linked to ONE another.

The correct answer is (d) 1965

The best I can EXPLAIN: Robert Holley of Cornell University, after seven years of work in 1965 reported the first base sequence of a YEAST transfer RNA. This tRNA composed of 77 nucleotides and CARRIED the amino acid alanine.

The CORRECT option is (d) aa-tRNA

Explanation: Transfer RNA linked to an AMINO acid is TERMED as aa-tRNA. Transfer RNAS have the dual function of CARRYING an amino acid (as aa-tRNA) and recognizing a particular codon in the messenger RNA.

Correct option is (c) C. elegans

Explanation: In 1998 Andrew Fire of Carnegie INSTITUTE of Washington and Craig Mello of the University of Massachusetts and their colleagues conducted experiments on the nematode C. elegans which ULTIMATELY LED to the discovery of RNAI phenomena.

The correct option is (a) Neurospora

To explain I would SAY: In 1940s George Beadle and Edward TATUM of the California Institute of Technology STUDIED Neurospora, a tropical bread mold which led to the proposal of “one gene – one enzyme” HYPOTHESIS.

Correct option is (c) oocytes

To explain I would say: Oocytes are the ideal CANDIDATES for the STUDY of rRNA synthesis and PROCESSING. Amplification of rDNA is required by the fertilized egg to begin embryonic development; therefore oocytes contain HUNDREDS of nucleoli that actively manufacture ribosomal RNA.

Correct answer is (a) RIBOSOME

The best I can explain: On the messenger RNA strand, the ribosome moves along the mRNA from ONE codon to the NEXT in the consecutive blocks of three nucleotides.