transfers amino acids to the ribosome to build proteins. It is highly folded into an elaborate 3D structure and comprises about % of total RNA. It is also called as soluble RNA . • rRNA (ribosomal RNA): Single stranded, metabolically stable, make up the two subunits of ribosomes.
It constitutes % of the total RNA. It is a polymer with varied length from – nucleotides and gives ribosomes their shape. Genes for rRNA are highly conserved and employed for phylogenetic studies (Figure . ).
Feature B-DNA A-DNA Z-DNA Type of helix Right-handed Right-handed Left-handed Helical diameter (nm) . . . Rise per base pair (nm) .
. . Distance per complete turn (pitch) (nm) . .
. Number of base pairs per complete turn Topology of major groove Wide, deep Narrow, deep Flat Topology of minor groove Narrow, shallow Broad, shallow Narrow, deep Ribosomal RNA (r RNA ) Messenger RNA (m RNA ) Transfer RNA (t RNA ) Figure . : Types of RNA Summary Cells are composed of water, inorganic compounds and organic molecules. The biomolecules of the cells include carbohydrates, lipids, proteins, enzymes and nucleic acids.
Carbohydrates include simple sugars (monosaccharides) and polysaccharides. Polysaccharide serve as storage forms of sugar and structural components of cell. Lipids are the principle components of cell membrane, and they serve as energy storage and signalling molecules. Proteins are polymers of different amino acids, each of which has a distinct side chain with specific chemical properties.
Each protein has a unique aminoacid sequence which determines its 3D structure. - - . . PM Nucleic acids are the principle information molecules of the cell.
Both DNA and RNA are polymers of purine and pyrimidine nucleotides. Evaluation . The most basic amino acid is a. Arginine b.
Histidine c. Glycine d. Glutamine . An example of feedback inhibition is a.
Cyanide action on cytochrome b. Sulpha drug on folic acid synthesiser bacteria c. Allosteric inhibition of hexokinase by glucose- -phosphate d. The inhibition of succinic dehydrogenase by malonate .
Proteins perform