Proteins

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Proteins
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Proteins

• Account for more than 50 of dry weight of cells
• Instrumental in almost everything cells do
• Structure of Proteins is encoded for in your DNA

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Uses for Proteins

• Structure
• Support
• Storage
• Transport (hemoglobin)
• Signaling (hormones)
• Accelerate chemical reactions (enzymes)

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Casein in Milk
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Hormones
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Building blocks for Proteins

• Monomers of proteins Amino Acids
• they contain a carboxyl amino group
• There are 20 different kinds of amino acids
• the sequence of amino acids is unique for each
  protein

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Peptide Bonds

• The bonds between amino acids are called Peptide
  Bonds
• 2 amino acids joined together Dipeptide
• More than 2 amino acids joined together
  Polypeptide

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Polypeptide
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Each amino acid has

• 1. Hydrogenation
• 2. Carboxyl -
• 3. Amine
• 4. Carbon - R chain is what makes each amino
  acid different

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Some Major Protein Categories

• 1. Structural Proteins such as keratin in the
  hair horns of animals, collagen in connective
  tissues and the silk in spider webs

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Some Major Protein Categories

• 2. Storage Proteins such as ovalbumin in egg
  whites and casein in milk

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Some Major Protein Categories

• 3. Transport Proteins such as those in the
  membranes of cells that transport material into
  and out of the cells AND as oxygen carrying
  Hemoglobin in the red blood cells

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Some Major Protein Categories

• 4. Defensive Proteins such as Antibodies that
  provide protection against foreign substances
  that enter the bodies of all animals

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Some Major Protein Categories

• 5. Enzymes that regulate the rate of Chemical
  Reactions

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4 Levels of Protein Structure

• 1. Primary Structure - describes the sequence of
  amino acids

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4 Levels of Protein Structure

• 2. Secondary Structure - the
  3-Dimensional shape that results from the
  hydrogen bonding
• The bonding produces a spiral (Alpha Helix) plane
  or a folded (Beta Pleated Sheet) plane.
• A single polypeptide may have sections of both.
  Proteins whose shape is dominated by these 2
  patterns are called Fibrous Proteins

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4 Levels of Protein Structure

• 3. Tertiary Structure - folding due to
  interactions among R-groups along polypeptide
  chains.
• These are called Globular proteins. The tertiary
  structure helps stabilize the structure

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Stabilizing the Protein

• A) Hydrophobic Interactions - when hydrophobic
  R-groups congregate toward the center of a
  protein (away from Water)
• B) Disulfide Bonds - strong, covalent bonds
  between the sulfur atoms in cystine amino acids
  Bridges - helps stabilize protein

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4 Levels of Protein Structure

• 4. Quaternary Structure this describes a
  protein that is composed of two or more
  polypeptide chains.
• Ex. The globular protein Hemoglobin consists of
  4 peptide chains.

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Locate the Peptide Bond
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Put in your NOTECARDS

• 1. The four (4) components of an amino acid
• 2. The five (5) major Protein Categories
• 3. The four (4) levels of Protein Structure
• 1 NOTECARD