Proteins AP Biology Proteins Multipurpose molecules AP Biology

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Proteins AP Biology

Proteins AP Biology

Proteins Multipurpose molecules AP Biology 2008 -2009

Proteins Multipurpose molecules AP Biology 2008 -2009

Why are Proteins Most structurally & functionally diverse group? Function: involved in almost everything

Why are Proteins Most structurally & functionally diverse group? Function: involved in almost everything u u u u AP Biology 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)

How are Proteins structured? u H 2 O monomer = amino acids 20 different

How are Proteins structured? u H 2 O monomer = amino acids 20 different amino acids u polymer = polypeptide protein can be one or more polypeptide chains folded & bonded together large & complex molecules hemoglobin complex 3 -D shape AP Biology Ru. Bis. CO

What is the structure of Amino acids? central carbon u amino group u carboxyl

What is the structure of Amino acids? central carbon u amino group u carboxyl group (acid) u R group (side chain) u H O H | || —C— C—OH —N— | H R variable group different for each amino acid confers unique chemical properties to each amino acid w like 20 different letters of an alphabet w can make many words (proteins) AP Biology Oh, I get it! amino = NH 2 acid = COOH

Effect of different R groups: Nonpolar amino acids nonpolar & hydrophobic AP Biology Why

Effect of different R groups: Nonpolar amino acids nonpolar & hydrophobic AP Biology Why are these nonpolar & hydrophobic?

Effect of different R groups: Polar amino acids polar or charged & hydrophilic AP

Effect of different R groups: Polar amino acids polar or charged & hydrophilic AP Biology Why are these polar & hydrophillic?

. Ionize in cellular waters by donating H+ AP Biology

. Ionize in cellular waters by donating H+ AP Biology

Ionizing in cellular waters AP Biology H+ acceptors Acid/Base

Ionizing in cellular waters AP Biology H+ acceptors Acid/Base

Why do some amino acids contain Sulfur? Form disulfide bridges u u covalent cross

Why do some amino acids contain Sulfur? Form disulfide bridges u u covalent cross links betweens sulfhydryls stabilizes 3 -D structure H-S – S-H You wondered why perms smell like rotten eggs? AP Biology

How are proteins built? Peptide bonds covalent bond between NH 2 (amine) of one

How are proteins built? Peptide bonds covalent bond between NH 2 (amine) of one amino acid & COOH (carboxyl) of another u C–N bond u dehydration synthesis AP Biology H 2 O peptide bond

In which dirrection are proteins built? Polypeptide chains have direction N-terminus = NH 2

In which dirrection are proteins built? Polypeptide chains have direction N-terminus = NH 2 end u C-terminus = COOH end u repeated sequence (N-C-C) is the polypeptide backbone u can only grow in one direction AP Biology

How do Proteins make the shapes they do? And why is it important? Function

How do Proteins make the shapes they do? And why is it important? Function depends on structure u 3 -D structure twisted, folded, coiled into unique shape pepsin hemoglobin AP Biology collagen

Primary (1°) structure Order of amino acids in chain amino acid sequence determined by

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

Sickle cell anemia I’m hydrophilic! AP Biology Just 1 out of 146 amino acids!

Sickle cell anemia I’m hydrophilic! AP Biology Just 1 out of 146 amino acids! But I’m hydrophobic!

Secondary (2°) structure “Local folding” folding along short sections of polypeptide u interactions between

Secondary (2°) structure “Local folding” folding along short sections of polypeptide u interactions between adjacent amino acids u H bonds w weak bonds between R groups u forms sections of 3 -D structure -helix -pleated sheet AP Biology

Secondary (2°) structure AP Biology

Secondary (2°) structure AP Biology

Tertiary (3°) structure “Whole molecule folding” u interactions between distant amino acids hydrophobic interactions

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

Quaternary (4°) structure More than one polypeptide chain bonded together u only then does

Quaternary (4°) structure More than one polypeptide chain bonded together u only then does polypeptide become functional protein hydrophobic interactions AP Biology = skin & tendons collagen hemoglobin

Protein structure (review) R groups hydrophobic interactions disulfide bridges (H & ionic bonds) 3°

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

Protein denaturation Unfolding a protein u In Biology, size doesn’t matter, SHAPE matters! conditions

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

EAT Let’s build X some Proteins! AP Biology 2008 -2009

EAT Let’s build X some Proteins! AP Biology 2008 -2009

Ghosts of Lectures Past (storage) AP Biology 2007 -2008

Ghosts of Lectures Past (storage) AP Biology 2007 -2008

Chaperonin proteins Guide protein folding u u AP Biology provide shelter folding polypeptides keep

Chaperonin proteins Guide protein folding u u AP Biology provide shelter folding polypeptides keep the new protein segregated from cytoplasmic influences

Protein models Protein structure visualized by X-ray crystallography u extrapolating from amino acid sequence

Protein models Protein structure visualized by X-ray crystallography u extrapolating from amino acid sequence u computer modelling u lysozyme AP Biology