Co 2h co 2h enantiomers non superimposable mirror

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: rginine phenylalanine aspartate lysine leucine asparagine glutamate histidine serine valine Charge is dependent upon pH Stereo Isomers (Enantiomers) 20 amino acids used in protein synthesis Group I: nonpolar Alanine (A) Isoleucine (I) Leucine (U) Methionine (M) Phenylalanine (F) Proline (P) Tryptophan (W) Valine (V) Group II: polar Asparagine (N) Cysteine (C) Glutamine (Q) Glycine (G) Serine (S) Threonine (T) Tyrosine (Y) Group III: charged Arginine (R) Aspartic Acid (D) Glutamic Acid (E) Histidine (H) Lysine (K) Isomer ( “same unit ”): two molecules with the same molecular formula, but arranged differently. CO 2H CO 2H Enantiomers : Non- superimposable mirror image molecules. “Right-handed ” [Dextro -] & “Left-handed ” [L evo -] versions of the molecule. C CH 3 L isomer L- Dopa Heyer H NH 2 NH 2 C H CH 3 D isomer D-Dopa 9 Biological Chemistry Stereo Isomers (Enantiomers) Peptide Bonds Link Amino Acids One of the great mysteries of the origin of living cells — • All non-biological synthesis reactions of organic molecules produce both D- and L- isomers in equal yield. • And all non-biological reactions using organic molecules as reactants react with both D- and L- isomers equally. • Yet, living cells are constructed only of D-sugars and their derivatives, and only L-amino acids and their derivatives! Peptide bond formation L- Dopa D-Dopa (biologically active) • Amino acids linked by dehydration synthesis Æ “peptide bond” • Polymer of amino acids = polypeptide • Different polypeptides have different amino acid sequences (biologically inactive) Protein Shape Determines Function • Specific 3-D shape • Shape is critical to function 3. Nucleic Acids — Information & Energy Carrying Molecules • Used for: – Information (DNA, RNA) – Cellular Energy (ATP) • Monomer: – Nucleotide • Polymer: • Denaturation = loss of shape and function Nucleotides • 5 possible types of Nitrogenous Base – Nucleic acid Ribbon model of lysozyme protein • 1, 2, or 3 phosphates off #5 carbon of sugar Human chromosomes Nucleic Acids are linear polymers of Nucleotide monomers • 2 possible types of C5 Sugar •Nucleotides to make RNA = Ribose sugar + A, G, C, or U base •Nucleotides to make DNA = Deoxyribose sugar + A, G, C, or T base Heyer Condensation reaction between •phosphate on #5 carbon of the sugar in one nucleotide, and •the hydroxyl on #3 carbon of the sugar in the other nucleotide Polymer forms sugar-phos...
View Full Document

Ask a homework question - tutors are online