Chapter 15

• Worked with the bread mold, Neurospora
• Made genetic mutants
• related mutations to ENZYME Productions

"One gene, one enzyme" theory of inheritance

Used B&T's methodology to study te STEPS in arginine biosynthesis.

• Built from Amino Aids
• Amino Acids linked to make a POLYPEPTIDE
• FOUR groups attached to a central C(a).
• TWENTY different ones are used to make proteins

Peptide Bonds

• 1) Primary
• 2) Secondary
• 3) Tertiary
• 4) Quaternary

• The sequence of amino acids
• It has TWO DISTINCT ends: amino (N) and carboxyl (C).

N-C-C-N-C-C....N-C-C-O^-

• Formed by regions of SELF-FOLDING of the polypeptide chain.
• How it folds depends on the SIZES and CHARGES of the R groups.
• The shape is maintained by HYDROGEN BONDS

• One polypeptide can ave regions of both alpha helices and B pleated sheets
• Most commonly EITHER an alpha helix OR a B pleated sheet.

The 3-D shape of the FULLY FOLDED polypeptide

• 1) Hydrogen Bond
• 2) Ionic Bond
• 3) Hydophobic Interaction
• 4) Disulfide Bridge
• 5) Van der Waals interaction

Some proteins have TWO OR MORE polypeptides joined together by weak bonds. Each is called a subunit.

• One "word" = codon
• If 1 base = 1 codon: then there are 4 possible codons
• If 2 bases = 1 codon: then there are 4² = 16 possible codons
• If 3 bases = 1 codon: then there are 4³= 64 possible codons