Nucleoside vs Nucleotide: Key Component Difference
Understanding the distinction between a nucleoside and a nucleotide is crucial. The primary difference lies in the presence of a phosphate group.
Nucleoside Structure
A nucleoside consists of two main components:
- A nitrogenous base (like adenine, guanine, cytosine, thymine, or uracil).
- A five-carbon sugar (either ribose or deoxyribose).
Nucleotide Structure
A nucleotide is essentially a nucleoside with one or more phosphate groups attached.
- Nucleoside
- One or more phosphate groups.
Identifying the Differentiating Element
The key element present in the phosphate group, and therefore in a nucleotide but not typically in a nucleoside, is phosphorous.
- The phosphate group has the chemical formula $ \text{PO}_4^{3-} $. This group clearly contains phosphorous (P) and oxygen (O).
- While oxygen is present in the sugar moiety of both nucleosides and nucleotides, phosphorous is unique to the phosphate group added to form a nucleotide.
- Carbon and nitrogen are fundamental components of the nitrogenous base and the sugar, present in both nucleosides and nucleotides.
Therefore, phosphorous is the element present in a nucleotide that is absent in a nucleoside.
Important Questions from Structure and Function of Biomolecules
- Which one of the following coenzymes is utilised by alanine racemase for the conversion of L-Alanine to D-Alanine?
- Which of the following show(s) optical activity at 100 mM concentration in water?
An octapeptide composed of these L-amino acids – Lys, Thr, Ser, Met, Arg, Trp, Tyr, Glu was subjected to analyses with the following outcomes:
P. The N-terminal sequencing analysis by Sanger's method yielded 'Ser' at the N-terminus
Q. Chymotrypsin treatment gave a pentapeptide, a ‘Tyr' containing dipeptide and a free ‘Glu'
R. Cyanogen bromide treatment gave two tetrapeptides
S. Trypsin treatment gave two tripeptides and a dipeptide
Which one of the following is the correct octapeptide sequence?
- Which of the following amino acids contain(s) two chiral carbons?
- Terpenoids are made of ________ units
