Ch. 3 The Four Most Important Organic Biological Compounds

1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids

• C:H:O ratio is 1:2:1 (CH20)n

• Simple sugars: glucose, fructose

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)

1) Carbohydrates

Fig 3.7

Glucose

Fructose

Formation of a Disaccharide

C12H22O11

Glucose Fructose

H2O (water)

Sucrose

A portion of a polysaccharide

Monosaccharides

C6H12O6

(Simple sugars)

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)

Fig 3.9B

Cholesterol

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