DNA and RNA Quiz

What would be the effect on histone proteins in the nucleus, on neutralisation of their positive charge?

• They would bind the DNA tighter.

• They would separate from DNA.

• They would no longer attract each other.

• They would cause supercoiling of DNA.

A DNA molecule is 160 base pairs long. It has 30% guanine. How many adenine bases are present in this DNA molecule?

• 48

• 64

• 96

• 192

In prokaryotes like E.coli the DNA in the nucleoid region is organised as

• negatively charged DNA wrapped around histone

• densely packed chromatin with NHC proteins

• large loops held by the proteins

• many repeating units of nucleosomes.

Given below is a list of steps Meselson and Stahl carried out in their experiment to prove that DNA replication is semi-conservative. Select the option that gives the correct sequence of steps followed by them.

• (ii) → (iv) → (iii) → (i) → (v)

• (i) → (ii) → (v) → (iv) → (iii)

• (iii) → (iv) → (i) → (ii) → (v)

• (iv) → (iii) → (ii) → (v) → (i)

Meselson and Stahl carried out centrifugation in CsCl₂ density gradient to separate:

• DNA from RNA

• DNA from protein

• the normal DNA from 15N-DNA

• DNA from tRNA.

A region of coding strand of DNA has the following nucleotide sequence 5′-ATGCGGC-3′. The sequence of bases on mRNA transcribed by this would be

• 5'-AUGCGGC-3′

• 3′-AUGCGGC-3'

• 5'-TACGCCG-3′

• 3'-TACGCCG-5'

In a bacterium, when RNA polymerase binds to the promoter on a transcription unit during transcription, it

• terminates the process

• helps remove introns

• initiates the process

• inactivates the exons.

When an amino acid is coded by more than one codon, the genetic code is said to be

• universal

• punctuate

• commaless

• degenerate.

During elongation process of translation, the peptide bond formation between amino acids is catalysed by

• ribosomal RNA

• transfer RNA

• messenger RNA

• small nuclear RNA.

Total number of nucleotide sequences of DNA that codes for a hormone is 1530. The proportion of different bases in the sequence is found to be adenine = 34%, guanine = 19%, cytosine = 23%, thymine = 19%. Applying Chargaff's rule, what conclusion can be drawn?

• It is a double stranded circular DNA.

• It is a single stranded DNA.

• It is a double stranded linear DNA.

• It is a single stranded DNA coiled on histones.