Proteins
Protein Basics
• Made of C,H,O, N
SPONCH
• Monomers = amino acids
- 20 different types of amino acids used to
make proteins
• Proteins are the polymer also called a
polypeptide
Meet the monomer –Amino acid
• 3 main parts
- Amino group NH2
- Carboxyl group COOH
- R group (side chain)
each of the 20 types
of amino acids have
a unique R group
Proteins form from chains of amino acids
Proteins vary in length – can be 1,000s of amino acids long
Proteins Shape
• A protein’s shape is determined by the order
that amino acids are joined in
• The shape of a protein determines its function
Hemoglobin
antibody
enzymes
polymerase
Protein Structure
Four Levels of Structure allow for any shape
2-28
Protein Structure – Primary Structure
• Primary structure is the order of the amino acids that
make up a protein.
- the interactions of the R groups on each amino acid
cause the molecule to bend and fold – different
arrangements create different shapes
- as a result- the order of
amino acids determines
the shape of the protein
- shape determines function
- changing a single amino acid can change a protein’s
shape.
Protein Structure- Secondary Structure
• The folding proteins often assume one of two
general shapes
– pleated sheets or an alpha helix these are the
protein’s secondary structure.
- hydrogen bonds between amino acids
stabilize the secondary structure
Alpha Helix
Protein Structure – Tertiary Structure
• The coiled or pleated structures continue to fold until
they form a complex three dimensional structure.
- most proteins are completed at this stage and are
fully functioning proteins.
Remember: Shape determines function
Protein Shape-Quaternary Structure
• Some more complex proteins are assembled
from two
or more protein molecules.
- Insulin – 2 forms – 2 proteins or 6 proteins
- Hemoglobin – 4 proteins
Protein Functions
Proteins are the Worker Molecules of Living Things
 Enzymes - proteins that allow chemical reactions to
occur in living things
 Antibodies – proteins that protect the body from
infection
 Structure – cytoskeleton, hair, nails, muscles, spider
web, silk, feathers ,horns, hooves etc….
 Hormones – chemical messengers
 Cell membrane – proteins can act as channels through
the cell membrane
- receptor proteins found on membrane
transmit signals to the inside of cells
• Hemoglobin – protein found in blood that carries oxygen
Proteins can be Denatured
• Denatured proteins are proteins that lose their shape
- if they lose their shape, they also lose their
…
Function
- What can cause a protein to become denatured?
Exposure to: A Strong Acid
A Strong Base
Heat
An organic solvent: Alcohol or Acetone
- Denatured proteins can lose quaternary, tertiary and
secondary structure
- Primary Structure is left untouched
Denatured Proteins
Vocabulary for the Protein Pro
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Polypeptide
R – Group
Peptide Bond
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure
Enzymes
Antibodies
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Cell Membrane Proteins
Hormones
Denatured Protein
4 things that denature
proteins