Specic order of amino acids largely determines

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Unformatted text preview: uaternary: arrangements among >1 polypepHde chains •  if only 1 chain, no quaternary structure PolypepHde chain β Chains Iron Heme α Chains Collagen Hemoglobin Quaternary Structure Importance of primary structure to funcHon •  1 amino acid change (primary structure) can affect a protein’s final structure, ability to funcHon –  Ex. sickle- cell disorder (inherited) due to 1 amino acid difference in protein hemoglobin (ulHmately, due to heritable change in DNA) normal red blood cell Sickle shaped RBC 11 Fig. 5- 22a Normal hemoglobin Secondary and terHary structures β α Quaternary structure Normal hemoglobin (top view) FuncHon β Fig. 5- 22b Primary structure changed Normal RBC Sickle- cell hemoglobin Val His Leu Thr Pro Val Glu 1 2 3 4 5 6 7 Exposed hydrophobic region a.a. #6 valine- nonpolar β subunit α Quaternary structure FuncHon α Molecules do not associate with one another; each carries oxygen. Secondary and terHary structures a.a. #6 Glutamic acid- electrically charged β subunit Val His Leu Thr Pro Glu Glu 1 2 3 4 5 6 7 Primary structure Sickle- cell hemoglobin β β α •  Molecules interact, clump in blood vessels, damage organs, painful. Sickle cell RBC DenaturaHon inacHvates proteins; wrong shape = lost funcHon •  change in temp, pH, salt conc., etc. can unravel proteins (largely irreversible) –  Explains danger of high fever (>105°F) •  level affected first __ ? (weak bonds) hep://highered.mcgraw- animaHon__protein_denaturaHon.html DenaturaHon Normal protein RenaturaHon Denatured protein 12 5.5: Nucleic acids store and transmit hereditary info, contain recipes for proteins •  2- x strand deoxyribonucleic acid (DNA) & 1- x strand ribonucleic acid (RNA) are polymers of nucleo*des •  3 parts: 1. sugar (5- C: deoxyribose or ribose) 2. phosphate group 3. N- containing base Nucleic acids differ in the order of their nucleoHdes •  Phosphate & 5- C sugar same (backbone), order of N- containing bases may vary b/w nucleoHdes: –  DNA: A C G T (adenine, cytosine, guanine, thymine) –  RNA: A C G U ( “ “ “ uracil) RelaHonship b/w DNA, RNA? •  DNA =“code of life”, contains genes (recipes to build proteins) •  RNA =intermediate, copies recipe, builds a. a. chains •  Info flow: DNA → RNA → protein (Ch. 17) Code of life 4 leeers (nucleoHdes) Hemoglobin 13 •  All biomolecules but ? form polymers •  All “ “ ? part of human diet 14...
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