Foundation of Biochemistry Lecture 1

Cellular foundation Chemical foundation Physical foundation Genetic foundation Evolutionary foundation

Distinguishing features of living organisms: High degree of chemical complexities and microscopic organization. Systems for extracting, transforming and using energy from the environment ( help to do mechanical, chemical, osmotic and electrical work) A precise capacity for self replication and self assembly. Mechanisms for sensing and responding to alterations in their surroundings. Defined functions for each of their components and regulated interactions among them. A history of evolutionary change.

Cellular foundation Cells: Structural and functional unit of all living organisms.

Cellular dimensions are limited by oxygen diffusion Lower limit set by the minimum number of each type of biomolecule required by the cell. Upper limit set by the rate of diffusion of solute molecules in aqueous system, especially oxygen.

Aerobic bacteria: require oxygen for survival Aerobic bacteria: require oxygen for survival. Anaerobic bacteria: don’t require oxygen for survival. In fact cannot survive in presence of oxygen.

E. coli the most studied prokaryotic cell

Cells build supramolecular structure

Monomeric subunits in proteins, carbohydrates, nulceic acids and polysaccharides are joined by covalent bonds. Macromolecules are held by noncovalent interactions-much weaker, individually than covalent bonds (hydrogen bonds, ionic interactions, hydrophobic interactions, van der waals interactions)

Chemical foundation Biomolecules are composed of carbon with a variety of functional groups Carbon accounts for more than half of the dry weight of the cell. Carbon can form single bond with hydrogen, double and triple bond with oxygen and nitrogen atoms respectively. Each carbon can make single bond with four other carbons.

Macromolecules are major constituent of cells Proteins : polymers of amino acids Nucleic acids (DNA and RNA): polymers of nucleotides Polysaccharides :polymers of simple sugars Lipids: greasy or oily hydrocarbon derivatives.

Three dimensional structure is described by conformation and configuration Stereoisomers: Molecules with same chemical bond, but different stereochemistry.