Proteins
 Organic compounds that contain carbon, hydrogen, oxygen
and nitrogen.
 Proteins are made up of long chains of the repeating units
called amino acids.
 There are 20 different human amino acids. These amino
acids combine in different orders and in different amounts to
create all the different proteins found in living organisms.
Example: You ate beef for dinner last night.
Beef muscle/protein is different than chicken,
pork or even human muscle/protein. As you eat
the beef your body digest it down into its useable
molecules or amino acids. These amino acids are
absorbed into your blood through the tissues of
your small intestines. These amino acids are
taken to your cells and your cells, under the
direction of your DNA, put these amino acids
back together into a chain that represents a protein
your body can utilize. For example: new blood
cells, new muscle cells etc….
 Our bodies use proteins for all body functions. They are
responsible for:
 Building new cells
 Repairing damages
 Maintaining our bodies
 Digesting our food
 Amino acids bond together into their chains with peptide
bonds, a type of covalent bond.
 Two amino acids bonded with a peptide bond is a dipeptide
 Three amino acids bonded with a peptide bonds is a
tripeptide
 Many amino acids bonded with peptide bonds is called a
polypeptide.
There are 2 categories of enzymes:
1. Functional proteins: They perform specific functions
within our bodies.
a. Enzymes: speed up chemical reactions like digestion
b. Insulin: transports glucose into cells
c. Antibodies: destroys pathogens
d. Hemoglobin: Transports oxygen
2. Structural proteins: They build and support our tissues
and other structures within our bodies.
a. Collagen: skin
b. Keratin: hair
c. Myosin: muscles
All proteins, both structural and functional, have a specific 3-D
shape.
If this 3-D shape is altered the protein will be damaged.
Example: Extreme cold to collagen-frost bite~ turns black
Extreme heat to collagen-burn ~ red and blisters
In order to achieve this specific 3-D shape, proteins must go
through at least three and maybe four levels of organization.
1. Primary Structure:
a. Linear in shape
i. A specific chain of amino acids in a sequence
according to DNA’s code.
2. Secondary Structure:
a. Chain acquires a specific orientation
b. H bonds fold and shape the amino acid chain.
i. Coils
ii. Right hand spiral/helix
iii. Pleated sheet
3. Tertiary Structure:
a. Final 3-D globular shape
b. It is this shape that dictates what a protein can do.
c. If the 3-D shape is altered, the protein can’t function
4. Quaternary Structure:
a. This level can be achieved when two protein chains
bond together to form one new protein.
Enzymes:
 Enzymes: are complex proteins used to speed up the rate of
digestion or the process of breaking down of food into
useable molecules, which are then transported, to the cells
by the blood.
 Anything, which speeds up the rate of a reaction, is called a
catalyst. So enzymes are catalyst to the process of
digestion.
 Enzymes make the reaction of digestion occur
10,000,000,000 times faster than it would occur without the
enzymes.
Example:
Digest candy bar with enzymes in 20min to 2 hours.
Digest candy bar without enzymes in 1,000 years.
 Enzymes are substrate specific. Each enzyme has a specific
shape and can only match up to and bond to one specific food
or substrate, which has a complementary shape.
 Enzymes following the Lock and Key Hypothesis.
o For every substrate there is one and only one enzyme
that causes the substrate to occur just like there is a
specific key, which fits a specific lock.
o A substrate is the substance which needs to be digested,
the food.
o Each enzyme has a specific shape associated with it.
This point/shape is called the active site.
Example:
Substrate
Enzymes
A
B
C
Substrae
EnzymeSubstrate
Complex
 How environmental factors affect enzymes:
o Denaturing of enzymes: agents such as heat/cold, acids
bases, and some metals such as mercury and lead
destroy the functional properties of enzymes by slightly
altering the shape of the enzyme’s active site.
Therefore, the enzyme does not function as well as it
should.
o Coenzymes: small organic molecules such as vitamins
and minerals bond to the enzyme and increases it rate of
function.
o Competitive Inhibitors: a molecule that has a
complementary shape to the enzymes active site so this
molecule (such as drugs and alcohol) bond to the active
site and block it from doing its real job.