ProteinsPolymers of amino acid monomers

DO NOW: What do you notice about the proteins below?

Proteins

• All Cells (life) are based on the structures and functions of proteins

• 50 % of dry matter in animals is protein

• All proteins made from same 20 amino acids

Monomers - Amino Acids

• Made of elements C,H,O,N,S

• 20 essential amino acids (building blocks of proteins)

• Combined in 20X1029 different ways

• Amino Acids (AA) form long chains called polypeptides

Amino Acids

• Humans synthesize 12 amino acids

• 8 are essential

Essential Amino Acids

• Not because they are more important to life than the others

• The body does not synthesize essential amino acids, making it essential to include them in one's diet in order to obtain them.

FUNCTION

• Function (job) of protein is based on its SHAPE!– Shape determined by amino acid

sequence– Change one amino acid - can change the

shape of the protein and make it useless

What do Proteins DO?

• Storage:• Transport:• Regulatory:• Movement:• Structural

• Enzymes

• Albumin (egg white)• Hemoglobin• Hormones• Muscles• Memmranes, hair,

nails, claws, scales, feathers

• Cellular Reactions

SHAPE

• Hydrogen bonds between amino acids cause the polypeptide chain to fold and twist into very special shapes

• Proteins can only maintain their shape in a narrow range of pH, temperature, moisture, and other factors

• LOSS OF SHAPE = LOSS OF FUNCTION!

Proteins

• Nucleic acids (DNA and RNA) contain instructions for making proteins

• A mutation (change) in DNA or RNA causes a change in the protein sequence (structure)

Levels of Protein Structure

• Primary Structure

• Secondary Structure

• Tertiary Structure

• Quarternary Structure

Primary Structure

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Levels of Protein Structure

Fibrous Proteins: • Primary - chain (squiggly)

– Straight polypeptide chain

• Secondary - helix (twisted)– Repeatedly coiled and folded

• Due to Hydrogen bonds

• Examples – Keratin – Collagen– Sickle cell– Spider web

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Levels of Protein Structure

Globular Proteins:- Polypeptide chains that are folded into compact spherical shapes. Involved in cellular and body functions.

• Tertiary: Globular (folds back on itself)– Hydrophobic parts end up in clusters at core of

protein

• Quarternary: Complex (looks squiggly, twisted, and folded– Two or more polypeptide chains

Primary

Secondary

Tertiary

Quaternary