Human Biochemistry
Amino Acids and Proteins
• there are about 20 amino acids that occur
naturally
• they are the basic “building blocks” of
life/proteins
NH2CHRCOOH
• condensation reactions will link amino acids
together to form polypeptides and eventually
proteins
• water is formed and they link together with a
peptide bond
• peptide bonds YouTube (1:14)
What is a protein video 3:38
Proteins have a complex structure which
can be explained by defining four levels of
structure
Primary Structure
• determined by the number, kind, and
order of a.a. in the polypeptide
• held together by simple peptide bonds
Secondary Structure
• the polypeptide then spontaneously folds into
regular, repeating structure because of hydrogen
bonding
Tertiary Structure
• highly specific looping and folding of the
polypeptide because of the following interactions
between their R-groups:
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covalent bonding
hydrogen bonding
ionic bonding
London dispersion forces
• this tertiary level is the final level of organization
for proteins containing only a single polypeptide
chain
Quaternary Structure
• linkage of two or more polypeptides to
form a single protein in precise ratios and
with a precise 3-D configuration.
• Protein folding
Quaternary Structure example
Carbohydrates
• most abundant class of biological
molecules
• range from simple sugars (glucose) to
complex carbohydrates (starch)
Monosaccharides
•
•
simplest sugars (single sugars)
two common isomers of monosaccharides
(C6H12O6)
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•
glucose
fructose
Disaccharides
•
two monosacharides bonded together by a
condensation reaction that creates a
glycosidic linkage
• three common disaccharides
1. sucrose - common table sugar
2. lactose - major sugar in milk
3. maltose -
Polysaccharides
• condensation of many glucose molecules
• serve principally as food storage and
structural molecules in plants
• three types of polysaccharides
1. Starches (plants)
– serve as storage depots of glucose
2. Cellulose (plants)
– plant cell walls
3. Glycogen
– serve as a form of energy storage in animals and
fungi
Lipids
3 Main Types of Lipids
1. Triglycerides (fats and oils)
• found in fatty tissue
• a condensation reaction called ester linkage
Saturated vs. Unsaturated fatty acids (2:51)
2. Phospholipids
• major structural components of cell
membranes
• polar “heads” love water (hydrophilic)
• uncharged “tails” avoid water (hydrophobic)
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3. Steroids
• cholesterol is the most abundant
and important steroid