Biomolecules
A. Carbohydrates
general formula: (CH2O)n
e.g., glucose - C6H12O6
soluble in H2O (many polar –OH groups)
major energy source for most cells; required by CNS
1. Monosaccharides (simple sugars)
- energy metabolism: glucose + 6 O2 → 6 CO2 + 6 H2O + energy ~> ATP
- building blocks of polysaccharides and nucleotides
ring structures:
pentoses (5C) ribose, deoxyribose
hexoses (6C) glucose, galactose, fructose
2. Disaccharides
maltose = gluc–gluc; sucrose = gluc–fruc; lactose = gluc–galac
3. Polysaccharides
- energy storage molecules
starch (plants)
glycogen (animals, stored in liver and muscle)
- structural polysaccharides
cellulose (plant fiber)
chitin
GAGs (connective tissues - EC matrix)
B. Lipids
mostly non-polar organic molecules
rich in C-H and C-C bonds
→ low solubility in H2O
1. Fatty acids - basic building blocks of lipids
long-chain hydrocarbons with carboxyl end COOH
saturated fatty acids: contain all C-C single bonds
- hydrocarbon chains pack closely → more solid (e.g., animal fat)
unsaturated fatty acids: contain C=C double bond(s) (monounsaturated, polyunsaturated)
- “kink” in the chain → more liquid (e.g., vegetable oil)
2. Triglycerides (triacylglycerols)
3 fatty acids + glycerol
- energy-rich molecules (= high calories)
~ 2X energy as carbohydrates per gram
- insoluble in H2O
- body fat (adipose tissue) functions for energy storage
3. Phospholipids
2 fatty acids + glycerol + phosphate group
amphipathic molecules - polar (head) and non-polar (tail) ends
e.g., phosphatidylcholine (lecithin)
phospholipid bilayer forms the basic structure of the plasma membrane
4. Steroids
cholesterol and derivatives; 4-ring structure
- cholesterol is an important component of the PM
- steroid hormones: cortisol, aldosterone, testosterone, estrogen
5. Eicosanoids
modified fatty acids with a ring (e.g., prostaglandins)
- function in intercellular signaling (paracrine)
- vasomotor effects, inflammation, pain
Docsity.com
