DNA & Inheritance: 16 MCQs with answers

Nucleotide

Nucleotides are the monomers that make up nucleic acids like DNA and RNA.

Cytosine

Guanine forms three hydrogen bonds with cytosine in DNA.

UAA

UAA is one of the three stop codons (UAA, UAG, UGA) that do not code for any amino acid.

Cytosine

Cytosine is a pyrimidine base, along with thymine and uracil.

Adenine

Adenine is a purine base, along with guanine.

AUG

AUG is the start codon that codes for methionine and initiates translation.

Amino acid

A nucleotide consists of a pentose sugar, a nitrogenous base, and a phosphate group; amino acids are not part of nucleotides.

False

The genetic code is unambiguous and specific; each codon codes for only one amino acid.

3.4 nm

The pitch of the DNA helix is 3.4 nm, with about 10 base pairs per turn.

DNA ligase

DNA ligase seals the nicks between Okazaki fragments on the lagging strand.

z gene

The z gene of the lac operon encodes beta-galactosidase, which hydrolyzes lactose.

It should be chemically inert

Genetic material must be able to replicate, be stable, mutable, and express itself; it is not required to be chemically inert.

Initiation

The sigma factor helps RNA polymerase bind to the promoter and initiate transcription.

RNA polymerase II

RNA polymerase II transcribes hnRNA, which is processed into mRNA.

It binds to the repressor and inactivates it

The inducer (e.g., allolactose) binds to the repressor protein, preventing it from binding to the operator, thus allowing transcription.

True

The lack of the 2'-OH group in deoxyribose makes DNA less reactive and more stable than RNA.