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• Polymers (long chains) of AMINO ACIDS
– arranged in specific sequence
– linked by PEPTIDE BONDS
– range in length from a
few to 1000+
AMINO ACIDS
•
•
•
•
building blocks of proteins
there are 20 common amino acids
structure of an amino acid:
elements included in a
protein:
-carbon
-hydrogen
-oxygen
-nitrogen
-sulfur (usually)
• Amino acids are linked together
through DEHYDRATION
SYNTHESIS to form PEPTIDE
BONDS
PROTEIN STRUCTURE
• a protein’s function depends on its
specific 3-D shape
Protein Shape:
• determined by environmental
conditions
• DENATURATION: protein loses its
natural shape, and therefore loses its
function! This can be caused by:
– extreme heat
– pH changes
Functions of Proteins
• structural support (e.g. hair, nails)
• signaling (e.g. hormones)
Functions of Proteins
• movement (contraction
of muscles)
• transporting oxygen in the
blood
Functions of Proteins
• defense (antibodies of
immune system)
• catalysis of reactions
(ENZYMES)
PROTEINS WORKING AS ENZYMES
ENZYMES:
• are proteins
• control the speed of
reactions (often they
increase the speed of
reactions)
• are not changed or “used up” by a
reaction; can be used over and over
• each enzyme is specific to a SUBSTRATE
• SUBSTRATE = the substance the enzyme
acts on
Substrate ==> enzyme-sub.==> product
+
complex
+
enzyme
enzyme
• ACTIVE SITE = region of an enzyme which
binds to the substrate
– is usually a pocket or groove on surface
– compatible “fit” between shape of
enzyme’s active site and shape of
substrate
Factors Affecting Enzyme Activity
1. Temperature:
–
as temp increases, reaction rate increases
–
BUT, if temp gets too high, enzyme
denatures and loses its shape and function
–
optimal range for human enzymes: 35-40°C
2. pH:
-optimal range for most enzymes: pH 6-8
*some enzymes operate best at extremes of
pH (e.g. digestive enzyme pepsin, found in
the acidic environment of the stomach,
works best at pH 2)
•
nucleic acids store and transmit hereditary
information
•
Two types of nucleic acids:
1. DNA
2. RNA
Structure of Nucleic Acids
• polymers made up of monomers called
NUCLEOTIDES
• Elements present:
-carbon
-hydrogen
-oxygen
-nitrogen
-phosphorus
•
each nucleotide consists
of:
1. a simple sugar
-deoxyribose in DNA
-ribose in RNA
2. phosphate group
3. a base (e.g. in DNA, the bases are A, G,
C, and T)
• nucleotides are joined
together in
DEHYDRATION
SYNTHESIS
• results in a “backbone”
with a repeating pattern
of sugar-phosphatesugar-phosphate...
1. DNA = Deoxyribonucleic acid
• forms the genetic code - the instructions
for the proteins (amino acid sequences)
of an organisms’ proteins
• is copied and passed
from one generation
of cells to another
2. RNA = Ribonucleic acid
• functions in the actual
synthesis of proteins
coded for by DNA