文档介绍：1. The molecular logic of life (1)
2. Cells (2)
3. Biomolecules (2)
4. Water (2)
5. Amino acids…etc (2)
6. Protein structure (4); Protein action (2)
7. Protein function (4); Experimental techniques (2)
8. Enzymes: catalysis and regulation (6)
midterm: review and Q&A (2); exam (2)
Chapter 2 Molecular Logic of Life
Some Important Chemical Concepts and Principles for Studying Biochemistry
1. Living matter posed mostly of the lighter elements
position of living matter is strikingly different from that of its physical environment (1810s)
The elements found in anisms also exist in nature (especially in seawater and atmosphere).
99% of the mass of anisms are made of H, O, N, and C.
H, O, N, and C are the lightest elements capable of forming one, two, three, and four bonds (in general, lightest elements form the strongest bonds).
The trace elements, although represent a miniscule fraction in anisms, all are absolutely essential to life (Fe, Cu, Mn, Zn, I, Mg).
Jellyfish and the sea water
2. Carbon was selected as the key element for life due to its versatile bonding capacity
Carbon accounts for more than one-half the cell dry weight.
Each carbon atom can form very stable single bonds with one, two, three, or four other carbon atoms, and double or triple bonds can also be formed between two carbon atoms.
Covalently linked carbon atoms can form linear chains, branched chains, and cyclic and cagelike(笼形的)structures.
To these carbon skeletons are added functional groups conferring specific activities to the molecules.
Molecules containing covalently bonding carbon backbones are pounds (including mainly alcohols, amines, aldehydes and ketones, carboxylic acids, sulfhydryls, … etc. Most biomolecules pounds.
Carbon atoms have a characteristic tetrahedral arrangement of their four single bonds. Carbon-carbon single bonds have freedom of rotation, but not double nor triple bonds.
No other chemical element has the capa