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Chapter 3

BIO-0013 Chapter Notes - Chapter 3: Peptide Bond, Amine, Chief Operating Officer

Course Code
Susan Koegel

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Chapter 3.1: Amino Acids + Polymerization
Non-ionized amino acid Ionized amino acid
Amino Group: NH2, NH3+, base: accepts a proton
Carboxyl Group: COOH, COO-, acid: donates a proton
Charged (acidic, basic)
Uncharged polar
Monomer1 + Monomer2Monomer1Monomer2
condensation/dehydration synthesis
Monomer1Monomer2 Monomer1 + Monomer2
Condensation/Dehyration of amino acids:
Peptide bond: c of carboxyl group + n of amino group
N-terminus C-terminus
R-group orientation: R-groups extend out of peptide backbone, can interact
Directionality: N-terminusC-terminus
Flexibility: single bonds on either side of peptide bond can rotate
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Chapter 3.2: Proteins
shapes functions examples
Long, cable-like Structural support for
saddle-shaped Binds DNA TATA box-binding
doughnut-shaped Forms a pore, allows
hydrophilic molecules to pass
through cell membrane
Primary structure: unique sequence of amino acids in protein
Frederick Sanger: each protein has unique sequence of amino acids
20n combinations of amino acid residues, length n
Secondary structure: functional groups interactions
Stabilized by:
hydrogen bonding: O on C=O, H on N-H
1. Alpha helix
Polypeptide backbone is coiled
Residues are 4 linear positions apart
2. Beta pleated sheet
Segments of peptide chain
Bend 180 degrees and fold
Tertiary structure: R-group + R-group or R-group+backbone
R-group interactions:
1. Hydrogen bonding: polar R + peptide backbone/polar R
2. Hydrophobic interactions: water + hydrophilic Rhydrophobic R coalesce
3. Van der waal’s interactions: electron movementpartial charges in nonpolar
4. Covalent bonding: disulfide bond- forms bridges, strong links
5. Ionic bonding: ionized acidic-basic side chains
Quaternary structure: combination of polypeptides
R-groups + R-groups, peptide backbones
Example: Hemoglobin
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