What is Biochemistry and what is meant by “Everyday Biochemistry?
• Biochemistry aims to explain 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?
• Carbon has a unique ability to form up to four stable covalent bonds because of its four unpaired electrons. These can be single, double, or triple bonds.
• The six elements that predominate in living organisms are H, O, C, N, P, and S, which together form the common functional 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).
• Metabolic pathways often consist of linked biochemical reactions in which the product of one reaction is the reactant for another.
• Living cells are highly ordered structures surrounded by a lipid membrane; cells obtain energy from the Sun or from oxidation–reduction reactions to support metabolic processes.
• Cells communicate with each other by using a biochemical process called signal transduction, which involves the binding of molecules to receptor proteins, thus affecting the signaling activity of the receptors.
• Within ecosystems, organisms undergo complex interactions with one another, which can be understood only by studying key biochemical processes.
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 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 single-stranded RNA copies of protein-coding sequences called mRNA molecules, which are translated into proteins by tRNA and ribosomes (including rRNA).
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 and can be seen in both the simplicity of the DNA double helix and the complexity of proteins.
• 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 with high sequence conservation at the amino acid level usually have similar three-dimensional structures and biochemical functions. However, proteins with very different amino acid sequences can also have similar overall structures, which may or may not correspond to similar biochemical functions.
Everyday BioChem 