Proteins

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Proteins
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• Proteins

Diverse groupMade of Amino Acids
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Proteins

• Most structurally functionally diverse group
• Function involved in almost everything
• Enzymes (pepsin, DNA polymerase)
• Structural Support (keratin, collagen)
• Transport of substances (hemoglobin, aquaporin)
• Hormones (insulin other hormones)
• Defense (antibodies)
• Contraction and Movement (actin myosin)
• Storage (bean seed proteins)

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Proteins

• Structure
• monomer Amino Acid
• 20 different amino acids
• polymer Chains of AA
• protein can be one or more polypeptide chains
  folded bonded together
• large complex molecules
• complex 3-D shape

hemoglobin
growthhormones
Rubisco
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Amino 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)

R
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Building proteins

• Peptide Bond
• covalent bond between NH2 (amine) of one amino
  acid COOH (carboxyl) of another
• CN bond

dehydration synthesis
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Primary (1) structure

• Chain of Amino Acids
• amino acid sequence determined by gene (DNA)
• slight change in amino acid sequence can affect
  proteins structure its function
• even just one amino acid change can make all the
  difference!

lysozyme enzyme in tears mucus that kills
bacteria
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Sickle cell anemia
Imhydrophilic!
But Imhydrophobic!
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Protein structure (review)
R groups hydrophobic interactions disulfide
bridges (H ionic bonds)
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multiple polypeptides hydrophobic interactions
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amino acid sequence peptide bonds
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determinedby DNA
R groups H bonds
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Protein structure function

• Function depends on structure
• 3-D structure
• twisted, folded, coiled into unique shape

pepsin
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Protein denaturation

• Unfolding a protein
• alter 3-D shape
• some proteins can return to their functional
  shape after denaturation, many cannot

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• Lets build some
• Proteins!