Biochemistry General

Biochemistry General

What is Biochemistry?

A. Biochemistry is concerned with structural chemistry. It seeks to determine the structures of molecules found in living systems in order to understand structure-function relationships.

B. Biochemistry is concerned with chemical change, this is reflected in the stu dy of metabolic pathways

C. Biochemistry is concerned with information which has accumulated through evolution and is preserved in DNA (or sometimes RNA). These nucleic acid sequences code for amino acid sequences, which result in folded proteins. These proteins are often catalysts (enzymes) and some of them are regulated (able to sense the chemical state inside the cell and, in some cases, the outside)

History of biochemistry:

(Proteins - enzymes)
1828 Wohler --> synthesized a biological compound (urea) from ammonium cyanate (an inorganic chemical)! NH4⁺ NCO^-

1897 the Buchner brothers (Eduard and Hans) demonstrated that alcoholic fermentation could occur in a cell-free extract.

1926 J.B. Sumner demonstrated that an enzyme (urease) was a protein and could be crystallized (indicative of fixed molecular structure and purity)

set stage for Perutz and Kendrew's work on X-ray structure of myoglobin and hemoglobin

Nucleic acid polymers (DNA and RNA)

Another series of discoveries surrounding nucleic acids: Miescher; Mendel; Avery, McCarty, and McLeod; Watson and Crick; Hershey and Chase

Distinguishing Characteristics of Living Systems

a. They are complex, that is they are highly organized (cell - nucleus - chromosome - nucleosomes - DNA base pairs - bases). This organization has physical chemical implications.

b. They are capable of self-replication (biochemistry comes from genetics)

c. They can transform energy. Energy is required to create order (G = H -TS)

Implications of Chemistry for Biology

a. There is an underlying simplicity in the molecular organization of cells (similar proteins are found in E. coli and in humans).

b. All living forms have a "common ancestor" (evolution). Biochemists seek a "logical" molecular path upward.

c. Identity (phenotype) of organism is determined by its set of nucleic acids (genotype) and proteins (gene products) and the regulation of their expression (interaction with the environment).

d. There is a molecular economy in living systems; some molecules appear to have an advantage over many others and are used repeatedly (ATP).