The Versatility of Proteins in Biology

The Versatility of Proteins in Biology

This article explores the diverse roles that proteins play in biological systems. From enzymes like pepsin and DNA polymerase that catalyze chemical reactions, to structural proteins like keratin and

About The Versatility of Proteins in Biology

PowerPoint presentation about 'The Versatility of Proteins in Biology'. This presentation describes the topic on This article explores the diverse roles that proteins play in biological systems. From enzymes like pepsin and DNA polymerase that catalyze chemical reactions, to structural proteins like keratin and. The key topics included in this slideshow are . Download this presentation absolutely free.

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Slide1AP BiologyProteins  

Slide2AP Biology2008-2009 Proteins Multipurpose molecules

Slide3AP BiologyProteins, that’s some good shit  Most structurally & functionally diverse group  Function: involved in almost everything  enzymes  (pepsin, DNA polymerase)  structure  (keratin, collagen)  carriers & transport  (hemoglobin, aquaporin)  cell communication  signals   (insulin & other hormones)  receptors  defense  (antibodies)  movement  (actin & myosin)  storage  (bean seed proteins)

Slide4AP BiologyProteins  Structure  monomer  =   amino acids  20 different amino acids  polymer  =   polypeptide  protein can be one or more polypeptide chains folded & bonded together  large & complex molecules  complex 3-D shape Rubisco hemoglobin growth hormones H 2 O

Slide5AP BiologyAmino acids  Structure  central carbon  amino group  carboxyl group (acid)  R group (side chain)  variable group  different for each amino acid  confers unique chemical properties to each amino acid  like 20 different letters of an alphabet  can make many words (proteins) — N — H H C—OH || O R | —C— | H Oh, I get it ! amino  = NH 2 acid  = COOH

Slide6AP BiologyEffect of different R groups: Nonpolar amino acids Why are these nonpolar & hydrophobic? Why are these nonpolar & hydrophobic?  nonpolar & hydrophobic

Slide7AP BiologyEffect of different R groups: Polar amino acids  polar or charged & hydrophilic Why are these polar & hydrophillic? Why are these polar & hydrophillic?

Slide8AP BiologyIonizing in cellular waters H+ donors H+ donors

Slide9AP BiologyIonizing in cellular waters H+ acceptors H+ acceptors

Slide10AP BiologySulfur containing amino acids  Form   disulfide bridges  covalent cross links betweens sulfhydryls  stabilizes 3-D structure You wondered why perms smell like rotten eggs? H-S – S-H H-S – S-H

Slide11AP BiologyBuilding proteins  Peptide bonds  covalent bond between NH 2  (amine) of one amino acid & COOH (carboxyl) of another  C–N bond peptide bond dehydration synthesis H 2 O

Slide12AP BiologyBuilding proteins  Polypeptide chains have direction  N-terminus  = NH 2  end  C-terminus  = COOH end  repeated sequence (N-C-C) is the polypeptide backbone

Slide13AP BiologyProtein structure & function hemoglobin  Function depends on structure  3-D structure  twisted, folded, coiled into unique shape collagen pepsin

Slide14AP BiologyPrimary (1°) structure  Order of amino acids in chain  amino acid sequence determined by gene (DNA)  slight change in amino acid sequence can affect protein’s structure & its function  even just one amino acid change can make all the difference! lysozyme: enzyme in tears & mucus that kills bacteria

Slide15AP BiologySickle cell anemia I’m hydrophilic ! But I’m hydrophobic ! Just 1 out of 146 amino acids !

Slide16AP BiologySecondary (2°) structure  “ Local folding ”  folding along short sections of polypeptide  interactions between adjacent amino acids  H bonds  weak bonds between R groups  forms sections of 3-D structure   -helix   -pleated sheet

Slide17AP BiologySecondary (2°) structure

Slide18AP BiologyTertiary (3°) structure  “ Whole molecule folding ”  interactions between distant amino acids  hydrophobic interactions  cytoplasm is water-based  nonpolar amino acids cluster away from water  H bonds & ionic bonds  disulfide bridges  covalent bonds between sulfurs in sulfhydryls (S–H)  anchors 3-D shape

Slide19AP BiologyQuaternary (4°) structure  More than one polypeptide chain  bonded together  only then does polypeptide become functional protein  hydrophobic interactions collagen = skin & tendons hemoglobin

Slide20AP BiologyProtein structure (review) amino acid sequence peptide bonds 1° determined by DNA R groups H bonds R groups hydrophobic interactions disulfide bridges (H & ionic bonds) 3° multiple polypeptides hydrophobic interactions 4° 2°

Slide21AP BiologyProtein denaturation  Unfolding a protein  conditions that disrupt H bonds, ionic bonds, disulfide bridges  temperature  pH  salinity  alter 2° & 3° structure  alter 3-D shape  destroys functionality  some proteins can return to their functional shape after denaturation, many cannot In Biology, size doesn’t matter, SHAPE matters !

Slide22AP Biology2008-2009 Let’s build some Proteins! EAT X