Proteins!!

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Proteins!!

• By Mrs. Ettinger
• Life and Matter

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Function

• Function build structural materials and carry
  out cell metabolism.
•     Act as hormones, enzymes or carrying
  molecules.
•     Help transport substances into/out of a
  cell.
•     Help fight disease.
•     Make up keratin (nails), collagen
  (connective tissue) and muscle.

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Why are proteins important?

• They are the chief constituents of cell, tissue
  and body fluids
• They are important source of
• A) energy
• B) building blocks to repair and built tissues
  and organs
• C) as catalyst of chemical reactions

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Proteins in our diet

• We need to eat proteins daily to replace worn
  tissue
• The amount we need is depends on our age, weight,
  and physical activity
• Excessive amounts of protein in the diet turns is
  stored as fat.
• However, once protein in converted as a source of
  energy it cannot be converted back to protein

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Where do protein in our diet come from?

• Milk
• Eggs
• Cheese
• Fish
• Poultry
• Red meat

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• Structure
•     made out of C, H, O and N (sometimes S)
• Proteins are long polymers of monomers called
  amino acids.
•     proteins are sometimes called polypeptides.

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Amino acids

• defined as the building blocks of proteins.
•     joined together by a covalent bond called a
  peptide bond.
•     there are 20 different amino acids make up
  all of the proteins.
•     13 of the amino acids are essential.

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Structure of an amino acid
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Amino acids

• 1. amine group (-NH2)
• 2. carboxyl group (-COOH)
• 3. R-group (differs for the 20 different          
  amino acids)

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R-groups can be acidic or basic, polar or
nonpolar.  Some contain carbon rings.
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Proteins have four levels of organization

• 1.  the sequence of amino acids.
• 2.  amino acids within a chain can be twisted or
  folded.
• 3.  the chain itself can be folded resulting in a
  3-dimensional shape.
• 4.  specific folded protein chains (shapes) fit
  together like puzzle pieces

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Denatured.

• Proteins can be denatured (they lose their 3-D
  shape) by high heat or strong acids.

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Chemical Reactions review

• A chemical reaction is a process that changes one
  set of chemicals (the reactants) into another set
  of chemicals (the products.)
•     Whenever chemical bonds are broken, energy
  is released. Sometimes occurs spontaneously and
  other times needs a boost of energy.
•     Whenever new chemical bonds are made, energy
  is absorbed and stored. Usually requires a boost
  from a source of energy.
•     The activation energy (Ea) is the energy
  needed to get a reaction started.

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Enzymes

• are a special type of protein that acts as a
  biological catalyst.

Catalysts speed up a chemical reaction by
lowering the Ea but is not affected itself.
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More about enzymes

• Enzymes also provide a site where reactants can
  be brought together to react.
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• Substrate the reactants of enzyme-catalyzed
  reactions.
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• Active site an area of the enzyme that fits like
  a lock and key with the substrate (very
  specific). The active site and the substrate have
  complementary shapes.

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