Proteins Regents Biology Proteins Multipurpose molecules Regents Biology

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Proteins Regents Biology

Proteins Regents Biology

Proteins: Multipurpose molecules Regents Biology 2006 -2007

Proteins: Multipurpose molecules Regents Biology 2006 -2007

Proteins Examples u muscle u fingernails, claws u skin u hair u enzymes §

Proteins Examples u muscle u fingernails, claws u skin u hair u enzymes § example: pepsin u hormones insulin hemoglobin § example: insulin Regents Biology collagen (skin)

Proteins § Function: u many, many functions § hormones w insulin § movement w

Proteins § Function: u many, many functions § hormones w insulin § movement w muscle § immune system w protect against germs § enzymes w help chemical reactions Regents Biology

Proteins § Building block = amino acids amino amino acid – acid u 20

Proteins § Building block = amino acids amino amino acid – acid u 20 different amino acids H O H | || —N— —C—C—OH | H variable Regents Biology group

Amino acid chains § Proteins u amino acids chained into a polymer § Each

Amino acid chains § Proteins u amino acids chained into a polymer § Each amino acid is different u some “like” water & dissolve in it u some “fear” water & separate from it Regents Biology

Water-fearing amino acids § Hydrophobic “water fearing” amino acids u try to get away

Water-fearing amino acids § Hydrophobic “water fearing” amino acids u try to get away from water in cell u § the protein folds Regents Biology

Water-loving amino acids § Hydrophillic “water loving” amino acids u try to stay in

Water-loving amino acids § Hydrophillic “water loving” amino acids u try to stay in water in cell u § the protein folds Regents Biology

3 -D protein structure § Proteins fold & twist into 3 -D shape hemoglobin

3 -D protein structure § Proteins fold & twist into 3 -D shape hemoglobin growth hormone Regents Biology pepsin collagen

Proteins (Polypeptides) Four levels of protein structure: A. Primary Structure B. Secondary Structure C.

Proteins (Polypeptides) Four levels of protein structure: A. Primary Structure B. Secondary Structure C. Tertiary Structure D. Quaternary Structure Regents Biology

Primary Structure Amino acids bonded together by peptide bonds (straight chains) Amino Acids (aa)

Primary Structure Amino acids bonded together by peptide bonds (straight chains) Amino Acids (aa) aa 1 aa 2 aa 3 Peptide Bonds Regents Biology aa 4 aa 5 aa 6

Secondary Structure § 3 -dimensional folding arrangement of a primary structure into coils and

Secondary Structure § 3 -dimensional folding arrangement of a primary structure into coils and pleats held together by hydrogen bonds § Two examples: Alpha Helix Regents Biology Beta Pleated Sheet Hydrogen Bonds

Tertiary Structure § Secondary structures bent and folded into a more complex 3 -D

Tertiary Structure § Secondary structures bent and folded into a more complex 3 -D arrangement of linked polypeptides § Bonds: H-bonds, ionic, disulfide bridges (S-S) § Call a “subunit”. Alpha Helix Regents Biology Beta Pleated Sheet

Quaternary Structure § Composed of 2 or more “subunits” § Globular in shape §

Quaternary Structure § Composed of 2 or more “subunits” § Globular in shape § Form in Aqueous environments § Example: enzymes (hemoglobin) subunits Regents Biology

Its shape that matters! § Proteins do their jobs, because § of their shape

Its shape that matters! § Proteins do their jobs, because § of their shape Unfolding a protein destroys its shape wrong shape = can’t do its job u unfolding proteins = “denature” u § temperature § p. H (acidity) folded Regents Biology unfolded “denatured”