BIOMOLECULES You are what you eat: –CARBOHYDRATES –LIPIDS –PROTEINS –NUCLEIC ACIDS

Carbohydrates

MONOSACCHARIDES All have the formula (CH 2 O) n The most common and important monosaccharide is glucose, which is a six-carbon or hexose sugar, so has the formula C 6 H 12 O 6.

Glucose is the most abundant organic compound in nature. Reactions of cellular respiration transform glucose into ATP energy. Most important sugar in our diet Diabetics lack hormone insulin, which allows glucose to enter into cells to be used in mitochondria.

There are many isomers of glucose, (same chemical formula but different structural formulae). These isomers include fructose and galactose. Fructose: found in honey, tree fruits; berries; melons; and some root vegetables, such as beets, sweet potatoes, parsnips and onions

Galactose: found in dairy products, in sugar beets and gums. Galactose is less sweet than glucose and not very water-soluble. Humans do not have the enzymes needed to use galactose directly. It must be converted into glucose first.

Disaccharides Sugars that consist of two monosaccharides, joined by a glycosidic bond. Examples are: maltose (glucose-glucose), sucrose (glucose-fructose), and lactose (galactose-glucose) The formation of a glycosidic bond involves the formation of water as a by-product and is a dehydration synthesis reaction. (aka: condensation reaction)

Polysaccharides Large carbohydrate chains made up of more than 10 subunits. Are a way of storing glucose until it is required – starch in plants and glycogen in humans Also structural role: cellulose makes up plant cell wall

LIPIDS Diverse group: fats, phopholipids,steroids, and waxes Structurally: are not made up of repeating sub units. Common Properties: –they are all hydrophobic and do not dissolve in water –They all contain hydrogen, oxygen and carbon

4 types of lipids: 1.Fats –aka Triglycerides – long term energy storage. – concentrated source of energy- 1 g of fat has more than twice the energy of 1 g of carbohydrate –Also cushion organs and insulate

Structure of fats: 3 fatty acids + glycerol = triglyceride Formed by dehydration synthesis reaction

Fatty acids have long hydrocarbon chains with a carboxyl group at one end.

Saturated fatty acids can lie closely together and form weak Van der Waal bonds between molecules. They are solids at room temperature. They are usually animal fats.

Unsaturated fats are loosely packed because of the kinks in the hydrocarbon chain. They are oils at room temperature, and are usually from plants.

Trans-fatty acids: “the hidden fats” –are produced when hydrogen is added to unsaturated fats. (Hydrogenation) –Trans fats are solids at room temperature –Trans fats cause significant and serious lowering of HDL (good) cholesterol and a significant and serious increase in LDL (bad) cholesterol; make the arteries more rigid; cause major clogging of arteries; cause insulin resistance; cause or contribute to type 2 diabetes, and heart disease. – Now mandatory labeling of amount of trans fats in Canada. ( December 12, 2005)

Phospholipids : are part of cell membrane. They help to regulate what substances can enter cells and which can’t.

Steroids : cholesterol ( important in cell membranes), hormones such as testosterone and estrogen. They all have a 4 ring structure

Waxes: are formed from fatty acids and long-chain alcohols. They are commonly found wherever waterproofing is needed, such as in leaf cuticles, insect exoskeletons, birds' feathers and mammals' fur.