Biochem Chapter1-3

2 cardinal rules of biochem

1. Biochemical descriptions must be consistent with the rules/laws of physics and chemistry

2. mutations and selection account for the development of biochemical machinery

importance of covalent bonds for biomolecules

individual molecules are held together by strong covalent bonds

cell membrane

separates the interior and exterior environments

importance of compartmentalization within cells

creates function-specific subregions

organelles

highly compartmentalized cells

methods to get molecules to the right place

1. Membranes form enclosed spaces

2. non-homogeneous spaces without membranes (nucleoid)

3. protein scaffolds: allow for the assembly of proteins to regulate a process

4. active transport of components

5. “earmarking” (labeling) of proteins: can help to separate synthetic from degradative processes

exceptions to the central dogma

1. storage of genetic information in RNA (viruses)

2. RNA can act as an enzyme, structural protein, etc.

3 fundamental noncovalent bond types

1. hydrogen bonds

2. ionic bonds

3. van der waals interactions

noncovalent bond energy

8-20kJ/mol

covalent bond energy

hundreds of kJ/mol (e.g., C-H: 400kJ/mol)

ionic bonds

depend on electrostatic interactions between atoms of different charge

• 6kJ/mol

hydrogen bonds

can form when hydrogen is bound to an electronegative atom

• donor: O-H or N-H

• acceptor: O or N

• 8-20kJ/mol

van der waals interactions

dependent on transient changes in charge distribution

• 2-4kJ/mol

hydrophobic effect

the tendency of nonpolar molecules to associate with another in aqueous solvent