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AP Biology Proteins

AP Biology Proteins AP Biology 2008-2009 Proteins _______________

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Page 1: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Proteins

Page 2: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology 2008-2009

Proteins______________________________

Page 3: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

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

(pepsin, DNA polymerase) (keratin, collagen) (hemoglobin, aquaporin)

(insulin & other hormones)

(antibodies) (actin & myosin) (bean seed proteins)

Page 4: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Proteins Structure

monomer = 20 different amino acids

polymer = protein can be one or more polypeptide

chains folded & bonded together

Rubisco

hemoglobin

growthhormones

H2O

Page 5: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Amino acids Structure

(acid) (side chain)

variable group different for each amino acid

like 20 different letters of an alphabet

can make many words (proteins)

—N—H

HC—OH

||O

R

|—C—

|

H

Oh, I get it!amino = NH2 acid = COOH

Page 6: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Effect of different R groups:Nonpolar amino acids

Why are these nonpolar & hydrophobic?Why are these nonpolar & hydrophobic?

Page 7: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Effect of different R groups:Polar amino acids

Why are these polar & hydrophillic?Why are these polar & hydrophillic?

Page 8: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Ionizing in cellular waters H+ donorsH+ donors

Page 9: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Ionizing in cellular waters H+ acceptorsH+ acceptors

Page 10: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Sulfur containing amino acids Form

covalent cross links betweens sulfhydryls

You wonderedwhy permssmell like

rotten eggs?

H-S – S-HH-S – S-H

Page 11: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Building proteins Peptide bonds

C–N bond

peptidebond

dehydration synthesisH2O

Page 12: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Building proteins Polypeptide chains have direction

repeated sequence (N-C-C) is the

_____________________ can only grow in one direction

Page 13: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Protein structure & function

hemoglobin

3-D structure

twisted, folded, coiled into unique shape

collagen

pepsin

Page 14: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Primary (1°) structure

slight change in amino acid sequence can affect protein’s structure & its function

lysozyme: enzyme in tears & mucus that kills bacteria

Page 15: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Sickle cell anemiaJust 1

out of 146amino acids!

Page 16: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Secondary (2°) structure “ ”

folding along short sections of polypeptide

weak bonds

between R groups

-helix -pleated sheet

Page 17: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Secondary (2°) structure

Page 18: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Tertiary (3°) structure “ ”

interactions between distant amino acids

cytoplasm is water-based

nonpolar amino acids cluster away from water

covalent bonds between sulfurs in sulfhydryls (S–H)

anchors 3-D shape

Page 19: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Quaternary (4°) structure

only then does polypeptide become functional protein hydrophobic interactions

collagen = skin & tendons hemoglobin

Page 20: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Protein structure (review)

amino acid sequence

peptide bonds

determinedby DNA R groups

H bonds

R groupshydrophobic interactions

disulfide bridges(H & ionic bonds)

3°multiple

polypeptideshydrophobic interactions

Page 21: AP Biology Proteins AP Biology 2008-2009 Proteins _______________

AP Biology

Protein denaturation

conditions that disrupt H bonds, ionic bonds, disulfide bridges

alter 2° & 3° structure

destroys functionality

In Biology,size doesn’t matter,

SHAPE matters!