Molecular Basis of Inheritance - Online Test

Answer : Option A
Explaination / Solution:

DNA molecules are not directly involved in synthesis of protein. In protein synthesis, DNA, first undergoes transcription process and produce m-RNA. Translation process takes place and produce protein.

Answer : Option C
Explaination / Solution:

The genetic code is the set of "rules" that a cell uses to interpret the nucleotide sequence within a molecule of mRNA. This sequence is broken into a series of three-nucleotide units known as codons.

The three-letter nature of codons means that the four nucleotides found in mRNA — A, U, G, and C — can produce a total of 64 different combinations. Of these 64 codons, 61 represent amino acids, and the remaining three represent stop signals, which trigger the end of protein synthesis.

Because there are only 20 different amino acids but 64 possible codons, most amino acids are indicated by more than one codon. ( however, that each codon represents only one amino acid or stop codon.).

This phenomenon is known as redundancy or degeneracy, and it is important to the genetic code because it minimizes the harmful effects that incorrectly placed nucleotides can have on protein synthesis.

Answer : Option B
Explaination / Solution:

Genetic code is unambiguous, universal and degenerate. Codon in mRNA is read in contiguous fashion without any gap. There are no punctuations during reading of Codon.

Answer : Option B
Explaination / Solution:

An anticodon is a unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA. Each tRNA contains a distinct anticodon triplet sequence that can base-pair to one or more codons for an amino acid.

Answer : Option A
Explaination / Solution:

An operator is a segment of DNA to which a transcription factor binds to regulate gene expression by repressing it. The protein that does this is called a repressor. Repressors bind to operators to prevent transcription. The main operator (O2) in the classically defined lac operon is located slightly downstream of the promoter. Two additional operators, O1 and O3 are located at -82 and +412, respectively. Operator attach with template strand to initiate transcription process.

Answer : Option D
Explaination / Solution:

Lysine, encoded by the codons AAA and AAG, is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, and a side chain lysyl, classifying it as a charged, aliphatic amino acid. UUA, AUG and CCC do not code for Valine, cysteine and alanine respectively.

Answer : Option A
Explaination / Solution:

Central dogma of protein synthesis consists of transcription and translation. In transcription process, DNA is changed into mRNA and in translation step m-RNA produce specific protein.

Answer : Option A
Explaination / Solution:

During translation initiation in prokaryotes, a GTP molecule is required along with 30S ribosome, m-RNA with formyl-met-t-RNA. GTP provides energy and ribosomes provide site for translation.

Answer : Option D
Explaination / Solution:

The three codons, UAA known as ochre, UAG as amber and UGA as opal, that do not code for an amino acid but act as signals for the termination of protein synthesis. So they also Known bas termination codon. They are not represented by any tRNA and termination is catalysed by protein release factors.

Answer : Option C
Explaination / Solution:

A Balbiani ring is a large chromosome puff. Balbiani rings are diffused uncoiled regions of the polytene chromosome that are sites of RNA transcription and protein synthesis. They are formed in eukaryotic cells only.