Principles of Biochemistry

What is Biochemistry and what is meant by “Everyday Biochemistry?

● Biochemistry explains biological processes at the molecular and cellular levels.

● In vitro alcoholic fermentation using yeast cell-free extracts was one of the first experiments demonstrating the chemical basis of life.

● Biochemical applications are examples of Everyday Biochemistry, such as the development of new pharmaceutical drugs, advances in medical diagnostics, the biotechnology industry, and improvements in agricultural and environmental sciences.

How is life organized on Earth in a hierarchical structure?

● The six elements that predominate in nature are H, O, C, N, P, and S, which together form the common chemical groups NH2, OH, SH, PO32-, COOH, and CH3.

● The four major classes of small biomolecules are amino acids, nucleotides, simple sugars, and fatty acids.

● The most abundant macromolecules in nature are polymers of nucleotides (DNA, RNA), amino acids (proteins), and the simple sugar glucose (cellulose, amylose, glycogen).

● Living cells are highly ordered structures surrounded by a lipid membrane; cells obtain energy from the Sun or from oxidation–reduction reactions.

How is biochemical information stored and processed to preserve life?

● Deoxyribonucleotide base pairs in DNA consist of guanine hydrogen-bonded to cytosine (G-C) and adenine hydrogen-bonded to thymine (A-T). RNA lacks the nucleotide base thymine and instead contains the nucleotide base uracil, which forms hydrogen bonds with adenine (A-U).

● The right-handed DNA double helix contains two antiparallel strands stabilized by the formation of hydrogen bonds between G-C and A-T base pairs and by base stacking in the interior of the DNA helix.

● DNA replication makes faithful copies of DNA using G-C and A-T base pairing. DNA transcription makes complementary RNA copies of protein-coding sequences called mRNA molecules, which are translated into proteins by tRNA and ribosomes.

What are the determinants of biomolecular structure and function?

● Biological structure and function are governed by evolutionary processes that affect function. This general principle holds true for macromolecules, cells, and organisms.

● The evolutionary driving force for creating diverse protein structures is nucleotide changes in the coding sequences of genes, resulting from random mutation and natural selection.

● Orthologous genes are functionally related genes that have been evolutionarily conserved between species. Paralogous genes are functionally related genes present in the same species that have arisen from gene duplication.

● Proteins in solution are in constant motion as a result of the formation and disruption of noncovalent interactions; the dynamic motion of proteins is an important component of their biochemical function.

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