Biomolecules and Enzymes

The COO- group as part of R-COO-R' is an ester. Esters are formed from the reaction of a carboxylic acid with an alcohol. Amide (A) is -CONH2, amino (B) is -NH2, and acid (D) is -COOH. Esters are known for their pleasant fruity odors.

Collagen is actually the most abundant structural protein in skin, making up about 75-80% of its dry weight. It provides skin with strength, elasticity, and structure. As we age, collagen production decreases, leading to wrinkles and sagging skin.

Different enzymes catalyze different steps of protein synthesis - aminoacyl-tRNA synthetases, peptidyl transferase, etc. There's no single enzyme responsible for the entire process. Option A correctly states that it depends on the specific protein and enzymatic step involved.

Hormones are signaling molecules produced in small quantities by organisms, not classified as organic matter in the context of soil composition. Organic matter typically refers to bulk materials like crude proteins, carbohydrates, and vitamins that contribute to soil organic content and nutrient cycling.

Hemocyanin, found in arthropod blood including cockroaches, uses copper ions (Cu+/Cu2+) instead of iron to bind and transport oxygen. When oxygenated, copper turns hemocyanin blue, unlike the red color of iron-based hemoglobin. This color difference is why their blood appears blue-green.

Haemocyanin is a copper-based respiratory pigment found in arthropods and molluscs, unlike vertebrates' iron-based haemoglobin. Copper gives haemocyanin a blue color when oxygenated, contrasting with haemoglobin's red color. Cockroaches utilize haemocyanin for oxygen transport in their hemolymph.

In the tertiary structure of proteins (including keratin in hair), disulfide bonds form between the sulfur atoms in cysteine amino acid R groups. These covalent bonds provide structural stability and are responsible for hair's strength. Carbon-carbon bonds don't specifically link R groups, hydroxide is not a bond type, and dihydride is not a relevant term.

Nails are primarily composed of keratin, a tough fibrous protein that also forms hair and the outer layer of skin. Keratin provides nails with their hardness and protective properties. This is a fundamental fact in human biology.

There are 20 standard amino acids that are genetically encoded and incorporated into proteins during translation. These are the naturally occurring building blocks of proteins in all living organisms. Each has a distinct side chain that determines its chemical properties. The numbers 12, 15, and 25 are incorrect counts.

Manganese is a trace element present in very small quantities in the human body (10-20 mg), unlike sodium and potassium which are macrominerals present in much larger amounts (100-140 g). Aluminium is not considered essential for human life. Trace elements like manganese are required in minute quantities for proper enzyme function.

Plants synthesize proteins by linking amino acids together through peptide bonds. Amino acids are the building blocks of all proteins. Starch is a carbohydrate storage molecule, sugar provides energy, and fatty acids are used for lipid synthesis - none are direct protein precursors.

Bacillus thuringiensis form a solid protein crystal, the parasporal body, next to their endospores during spore formation. The parasporal body contains protein toxins that has been found to kill over 100 species of moths by dissolving in the alkaline gut of caterpillars and destroying the epithelium.

Streptomyces olivaceus are Gram positive bacteria with high GC content and are characterised by a complex secondary metabolism. They produce over two-thirds of the clinically useful antibiotics of natural origin. Cyanocobalamin is synthesised by utilising Streptomyces olivaceus.

A radioisotope used to label proteins differently from nucleic acids is 35S.