Proteins AP Biology Proteins Multipurpose molecules AP Biology

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Proteins AP Biology

Proteins AP Biology

Proteins Multipurpose molecules AP Biology 2006 -2007

Proteins Multipurpose molecules AP Biology 2006 -2007

Where is protein in our bodies? Hair Blood Enzymes AP Biology

Where is protein in our bodies? Hair Blood Enzymes AP Biology

Proteins Most structurally & functionally diverse group of biomolecules Function: involved in almost everything

Proteins Most structurally & functionally diverse group of biomolecules Function: involved in almost everything AP Biology enzymes (pepsin, polymerase, etc. ) structure (keratin, collagen) carriers & transport (membrane channels) receptors & binding (defense: antibodies) contraction (actin & myosin) signaling (hormones: insulin) storage (bean seed proteins)

Proteins Structure: monomer = amino acids 20 different amino acids polymer = polypeptide protein

Proteins 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 hemoglobin AP Biology Rubisco growth hormones

Amino acids Structure: central carbon amino group carboxyl group (acid) R group (side chain)

Amino acids Structure: central carbon amino group carboxyl group (acid) R group (side chain) variable group confers unique chemical properties of the amino acid AP Biology H O H | || —C— C—OH —N— | H R

Building proteins Peptide bonds linking NH 2 of one amino acid to COOH of

Building proteins Peptide bonds linking NH 2 of one amino acid to COOH of another C–N bond dehydration synthesis AP Biology peptide bond

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

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

Protein structure & function Function depends on structure 3 -D structure twisted, folded, coiled

Protein structure & function Function depends on structure 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) slight change in amino acid sequence can affect protein’s structure & it’s function even just one amino acid change can make all the difference! AP Biology lysozyme: enzyme in tears & mucus that kills bacteria

Sickle cell anemia AP Biology

Sickle cell anemia AP Biology

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

Secondary (2°) structure “Local folding” folding along short sections of polypeptide interaction between adjacent amino acids H bonds between R groups -helix -pleated sheet AP Biology

Secondary (2°) structure “Let’s go to the video tape!” AP Biology (play movie here)

Secondary (2°) structure “Let’s go to the video tape!” AP Biology (play movie here)

Tertiary (3°) structure “Whole molecule folding” determined by interactions between R groups hydrophobic interactions

Tertiary (3°) structure “Whole molecule folding” determined by interactions between R groups hydrophobic interactions w effect of water in cell anchored by disulfide bridges (H & ionic bonds) AP Biology

Quaternary (4°) structure More than one polypeptide chain joined together only then is it

Quaternary (4°) structure More than one polypeptide chain joined together only then is it a functional protein hydrophobic interactions collagen = skin & tendons AP Biology hemoglobin

Denature a protein Unfolding a protein disrupt 3° structure p. H salt temperature In

Denature a protein Unfolding a protein disrupt 3° structure p. H salt temperature In Biology, size doesn’t matter, SHAPE matters! unravels or denatures protein disrupts H bonds, ionic bonds & disulfide bridges destroys functionality Some proteins can return to their functional shape after denaturation, many cannot AP Biology

Protein structure (review) R groups hydrophobic interactions, disulfide bridges 3° multiple polypeptides hydrophobic interactions

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

Let’s build some Proteins! AP Biology 2006 -2007

Let’s build some Proteins! AP Biology 2006 -2007