Your cart is empty.
Practice each question, then open the answer or worked solution.
In a DNA strand the nucleotides are linked together by:
Ans: (b) phosphodiester bonds
A dinucleotide is made up of two nucleotides joined together by a 3′5′ phosphodiester bond. To construct a polynucleotide chain, more nucleotides are connected in a similar way.
A nucleoside differs from a nucleotide. It lacks the:
Ans: (c) phosphate group
A pento is linked to a purine or pyrimidine base. A nucleoside is a sugar that is either ribose or deoxyribose. A nucleotide is a sugar that has one or more phosphate groups connected to it.
Both deoxyribose and ribose belong to a class of sugars called:
Ans: (c) pentoses
Both deoxyribose and ribose belong to the Pentoses sugar family. The sugar molecule pentose has five carbons.
The fact that a purine base is always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix:
Ans: (c) uniform width throughout DNA
Purine always couples with pyrimidine to provide stability to the DNA strand. Because the sizes of the two bases differ, the arrangement is such that the bigger base forms a bond with a smaller base, making DNA 2nm thick and providing a uniform width to DNA throughout its length.
The net electric charge on DNA and histones is:
Ans: (c) negative and positive, respectively
A nucleosome is formed when negatively charged DNA is wrapped around positively charged histone. This explains the nucleus's ability to pack so much DNA into such a compact region.
The promoter site and the terminator site for transcription are located at:
Ans: (b) \[5^{\prime}\] (upstream) end and \[3^{\prime}\] (downstream) end, respectively of the transcription unit
As transcription continues from \[5^{\prime}\] to \[3^{\prime}\], the promoter sequence should be in front of upstream of the start site in the \[5^{\prime}\] end, and the terminator sequence should be in the \[3^{\prime}\] end downstream.
Which of the following statements is the most appropriate for sickle cell anaemia?
Ans: (d) All of the above
Because sickle cell anemia is an inherited condition, iron supplementation will not help. In persons with sickle cell anemia, the altered structure of RBCs confers malaria resistance.
One of the following is true with respect to AUG
Ans: (d) All of the above
The initiation code is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome, and it is one of the genetic codes. The start codon is ubiquitous and codes for methionine, an amino acid, in both prokaryotes and eukaryotes.
The first genetic material could be:
Ans: (d) RNA
There are numerous convincing pieces of evidence that RNA was the earliest genetic substance. However, as a catalyst, RNA proved reactive and unstable. As a result, DNA became a genetic material in the living world.
With regard to mature mRNA in eukaryotes:
Ans: (b) exons appear but introns do not appear in the mature RNA
Introns, also known as intervening sequences or noncoding sequences, are additional regions found in eukaryotic transcripts. They aren't found in either mature or processed RNA. Exons are the functional coding sequences. Splicing is the process of removing introns and joining exons to create functional RNAs.