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Ch. 3 The Four Most Important Organic
Biological Compounds
1.
2.
3.
4.
Carbohydrates
Lipids
Proteins
Nucleic Acids
1) Carbohydrates
•
C:H:O ratio is 1:2:1
•
Simple sugars: glucose, fructose
(CH20)n
 Structural units, used to make larger,
storage compounds:
1. Starch – energy storage in plants
2. Glycogen – energy storage in animals
3. Cellulose – plant cell walls (structure,
protection)
Fig 3.7
Glucose
Fructose
Monosaccharides
C6H12O6
(Simple sugars)
Glucose
Fructose
Formation of a
Disaccharide
H2O (water)
C12H22O11
Sucrose
A portion of a
polysaccharide
2. Lipids
•
Non-polar, hydrophobic (don’t dissolve in water)
•
(CH)nCOOH
•
Functions:
•
–
High-energy storage molecules
–
Transmit signals/messages (steroid hormones)
4 main types:
a) Fats
b) Phospholipids
c) Steroids
d) Waxes
A) Fats
• Triglycerides – most abundant lipids in
body, abundant energy!
Fig. 3.8B,C
-no double bonds
-has double bonds
B) Phospholipids
-cell membranes
C) Steroids
• No fatty acid chains
• Cholesterol:
– component of cell membranes
– Precursor for hormones (estrogen, testosterone)
Cholesterol
Fig 3.9B
D) Waxes
• Repel water
• Protect & lubricate
• Plant cuticle
• honeycombs
3) Proteins
• Made of amino acids
joined by peptide bonds
• enzymes
• cell parts like hair ,
nails, muscle fibers.
• Cell membrane
transporters
Fig. 3.12A
Fig 3.12C
Proteins continued
• DNA specifies the order of AA
• Order determines shape
• Shape determines function
Primary structure
Fig 3.14A-D
One AA substitution alters the form of hemoglobin,
resulting in sickle cells.
Anemia, circulatory problems, kidney failure,
enlarged spleen…..
4) Nucleic Acids
• DNA & RNA
– Sequence is the
code for
protein
synthesis
• Monomers of
Nucleotides
Fig 3.16A
The nitrogenous
bases of DNA
RNA contains: ribose instead of deoxyribose, and uracil
instead of thymine
Fig 3.16B,C: The
structure of DNA