Biomolecules and Enzymes

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.

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.

Cells are indeed the fundamental structural and functional units of the human body. All tissues and organs are composed of cells, which perform all basic life processes. This is a foundational concept in 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.

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.

The genetic code is degenerate in that most amino acids are encoded by more than one codon.

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.

This entropy is associated with the physical set up of a polymer chains that allines a compact or globular state in solution. This concept is most commonly applied to biological macromolecules such as proteins and RNA.

This mutation causes no change in the final protein product and can only be identified by sequencing the gene. Most amino acids that make up a protein are encoded by several different codons.

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

Chromoproteins are proteins, such as hemoglobin or rhodopsin containing a pigmented nonprotein group, as heme, riboflavin, or retinal.

Keratin - A fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair, feathers, nails, and hooves Collagen - A fibrous scleroprotein in bone and cartilage and tendon and other connective tissue; yields gelatin on boiling Elastin - A fibrous scleroprotein found in elastic tissues such as the walls of arteries.

Streptokinase is used to dissolve blood clots that have formed in the blood vessels.