Important Biological Compounds Chapter 3

Carbohydrates Sugars, starches, cellulose Carbon, hydrogen, oxygen (CH 2 O) n 2:1 ratio hydrogen to oxygen like water Monosaccharide – 1 sugar units Disaccharide – 2 sugar units Polysaccharides – many sugar units

Monosaccharides 3 – 7 carbon atoms Hydroxyl group bonded to each C except one; that C double bonded to an O which forms a carbonyl group Carbons are numbered starting with the C at the carbonyl group

Glucose – an important monosaccharide A hexose (6 C sugar) Used as an energy source in most organisms – cells oxidize glucose to produce ATP Glucose is also used to produce amino acids and fatty acids Is a structural isomer with fructose (found in fruit & honey) In cells is typically in ring form

Disaccharides – 2 monosaccharide units Maltose (malt sugar) = 2 glucose units Lactose (milk sugar) = glucose + galactose Sucrose (table sugar) = glucose + fructose During digestion these are hydrolyzed to form their monosaccharides

Polysaccharides – used for energy storage or structures Macromolecule – usually glucose units Starch – energy storage in plants 2 forms: amylose and amylopectin Glycogen – ‘animal starch’ – energy storage in animals, especially liver and muscle cells Cellulose – a structural carbohydrate found in plant cell walls

Lipids Nonpolar Fats, phospholipids, some cell pigments, steroids, and waxes Triglyceride – glycerol + 3 fatty acids Yield more than 2x energy per gram as carbohydrates

Saturated vs Unsaturated Fats Saturated fatty acids – contain the max number of H atoms Tend to be solid at room temp Are associated with increased risk of heart disease Unsaturated fatty acids – contain one or more carbon to carbon double bonds Tend to be liquid at room temp

Phospholipids One end is hydrophobic, one end hydrophilic This causes them to orient in an aqueous environment with the hydrophobic tails inside a double layer

Carotenoids Orange and yellow plant pigments In animals these are converted to vitamin A and then to retinal – the visual pigment Are carrots really good for your eyes??

Steroids Cholesterol – an essential component of animal cells; excess can build up on artery walls and lead to heart disease Reproductive hormones Bile salts