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BIOCHEMISTRY

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  1. BIOCHEMISTRY

  2. Biochemistry is the study of the chemical processes and transformations in living organisms

  3. Biochemistry is the study of the structure and function of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules

  4. All macromolecules are constructed from a few simple compounds

  5. Major Biomolecules • Proteins • Carbohydrates • Lipids • Nucleic acids

  6. Amino acids, nucleotides, and monosaccharides , serve as monomeric subunits of macromolecules: proteins, nucleic acids ,and polysaccharides

  7. PROTEINS

  8. Most abundant Biomolecules • In all cells and all parts of cells • Great variety • Provide structure • Also used to store energy • Produced by ribosomes in our cells

  9. Proteins are molecular instruments through which genetic information is expressed

  10. Enzymes Hormones Antibodies Transporters Lens protein of eye Milk proteins Structure Antibiotics ..they are used for

  11. Virtually all cellular reactions are catalyzed by ENZYMES

  12. 2 kinds ????? • Fibrous proteins: usually long and thin -provide structure e.g. muscles, hair, cartilage, veins, ducts etc Globular proteins: e.g. transport of oxygen and nutrients, defenders, maintain homestasis, transport electrons, catalyze reactions that would take longer in their absence

  13. All proteins are constructed from same set of 20 amino acids.

  14. So….. Amino acids are building blocks of proteins Monomers of proteins

  15. AMINO ACID GENERAL STRUCTURE Bonds btw 2 a.a are linked by a peptide bond

  16. Remember…. • Glycine (Gly) • Alanine (Ala) • Valine (Val) • Leucine (Leu) • Isoleucine (ILe)

  17. Serine (Ser) • Threonine (Thr) • Phenylalanine(Phe) • Tyrosine (Tyr) • Tryptophan (Trp)

  18. Aspartate (Asp) • Glutamate (Glu) • Aspargine (Asn) • Glutamine (Gln) • Proline (Pro)

  19. Lysine (Lys) • Arginine (Arg) • Histidine (His) • Cysteine (Cys) • Methionine(Met)

  20. Side chains define chemical nature and structures of different amino acids • So there are only 20 R-groups

  21. Amino acids with nonpolar R groups • Gly, Ala, Val, Leu, Iso, Phe, Try, Met, Pro • Non polar structure promotes hydrophobic interaction e.g. in aqueous solutions R chain cluster together in the interior of the protein • Do not participate in hydrogen bonding

  22. Proline is different because -side chain and its amino grp form a ring structure -described as an imino group • This difference contributes to the fibrous structure of collagen

  23. Uncharged polar side chains Ser, Thr, Tyr, Asp, Cys, Glu • Can participate in hydrogen bond at an alkaline pH

  24. Val , Leu , Ile • Branched chain amino acids • hydrophobic

  25. Phe , Tyr , Trp • Aromatic amino acids

  26. Cys , Met • Sulfur containing amino acids • Cysteine>>>DISULFIDE bond • Important in protein structure b/c it is an active component of site of enzymes

  27. Aspartic and Glutamic acid Amino acids with acidic side chains

  28. Lys , Arg , His • Basic amino acids

  29. Non standard amino acids • Hydroxyproline • Hydroxylysine • γ - carboxyglutamate

  30. ESSENTIAL AND NON ESSENTIAL AMINO ACIDS

  31. ESSENTIAL AMINO ACIDS MUST be taken from dietary sources • Val, Leu, Ile • Thr • Met • Phe, Trp • Lys, Arg,His

  32. These ten amino acids have long preserved life in man

  33. Amino acids are polymerized into peptides and proteins • Proteins are assembled from amino acids using information encoded in genes

  34. Single polypeptide chains • Multi subunit proteins

  35. CONJUGATED PROTEINS • Some proteins contain chemical groups other than amino acids • LIPOPROTEINS • GLYCOPROTEINS • METALLOPROTEINS

  36. PROTEIN STRUCTURE • There are four levels of protein structure • Primary structure • Secondary structure • Tertiary structure • Quaternary structure

  37. PRIMARY STRUCTURE • Sequence of amino acids • All covalent bonds • Peptide bonds and disulfide bonds

  38. SECONDARY STRUCTURE • Stable arrangements of amino acid residues giving rise to recurring structural patterns. • stabilized by hydrogen bonds btw the amino acids • 3D dimensional structure

  39. 2 types • Α-helix: when the hydrogen bonds are intrachain (within the same polypeptide chain) e.g. keratin in hair and skin • Β(pleated) sheath: interchain hydrogen bond producing a stable structure.

  40. TERTIARY STRUCTURE • 3-D folding of polypeptide chain • disulfide bonds between cysteine residues, hydrophobic interactions, hydrogen bonds and ionic interactions help to maintain the protein's tertiary structure

  41. QUATERNARY STRUCTURE • When a protein has two or more polypeptide subunits, their arrangement and relationship in space is referred to as quaternary structure e.g. di, tri or multimeric subunits

  42. denaturation • Process of unfolding and disorganizing proteins’ 2º and 3º structures Factors: • Heat ,organic solvents • Radiation, strong acids or bases • pH changes, ions of heavy metals-lead and mercury Hard boil an egg and you denature proteins that make up the egg