2.3 : Carbohydrates & Lipids Flashcards
what are the main elements in carbohydrates?
- carbon
- hydrogen
- oxygen
what are monosaccharides?
the simplest form of a carbohydrate = simple sugar
what are polysaccharides?
many monosaccharides combined through glycosidic bonds to form a lager carbohydrate (polysaccharide)
what are disaccharides?
a polysaccharide with two or more monosaccharides with glycosidic linkages, condensed together
what are isomers & examples?
- compounds that have the same component atoms in their molecules but different arrangements of the atoms.
- a-glucose & b-glucose
what are optical isomers & examples?
- compounds that have the same chemical properties but different arrangements, creating mirror images of each other.
- L-glucose & D-glucose.
what is the test for reducing sugars?
Benedict’s test.
what are the characteristics and uses of cellulose (polysaccharide) & how is it’s stabilised in its structure?
- strong, insoluble, tough, slightly elastic.
- fibres as cotton, manufacture into paper, explosives, rayon fibres for clothes.
- it’s structure is strengthened & stabilised through hydrogen bonds between adjacent glucose molecules in the same strand & parallel strands (in fibres).
what is starch made up of?
mixture of two polysaccharides :
-amylose : unbranched chain of thousands of linked
a-glucose units.
-amylopectin : shorter and branched chains of a-glucose units;
what is a monomer?
a basic molecule that can react together with monomer molecules to form a repeating chains of polymers during polymerisation.
what is a polymer?
a large molecule consisting of many identical monomers linked together via covalent bonds.
what are phospholipids?
molecule that has a hydrophilic head with a phosphate group and two hydrophobic tails from fatty acids joined by an alcohol group.
what is the difference between saturated & unsaturated lipids?
- saturated lipids : compounds that have single carbon bonds.
- unsaturated lipids : compounds that have double carbon-carbon bonds.
what are lipids built from 1) saturated and 2) unsaturated fatty acids called & examples?
1) saturated fats -butter, lard, cocoa butter.
2) unsaturated fats -olive oil.
(unsaturated fatty acids) what are monounsaturated & polyunsaturated fatty acids?
- monounsaturated fatty acids : when there is a single double bond in a carbon chain of a fatty acid.
- polyunsaturated fatty acid : when there are two or more double bonds in a carbon chain of a fatty acid.
why do fats with unsaturated fatty acids have a lower melting point?
as the unsaturated hydrocarbon tail doesn’t pack so closely in comparison to saturated fats –> meaning that molecules are able to vibrate more due to more space between molecules = melt faster.
what is the difference between CIS and TRANS fatty acids?
- CIS : two parts of the hydrocarbon chain are on the same side of the double bond.
- TRANS : two parts of the hydrocarbon chain are on opposite sides.
what do diets rich in trans fats cause?
cause an increase in levels of Low-density lipoprotein (LDL) cholesterol in blood = bad cholesterol.
(increased risk of coronary heart disease - block arteries & veins - lack of blood supply)
what are omega-3 fatty acids & where are the double bonds located?
-a naturally occurring polyunsaturated fatty acids.
(polyunsaturated = more than one double bond in backbone)
-the first double bond is always between the 3rd and 4th carbon atom from opposite end (=omega end) of a hydrocarbon chain to carboxyl group.
why are omega-3 fatty acids beneficial?
- produce hormones that regulate blood clotting, contractions, relaxation of artery walls.
- lower levels of HDL cholesterol –> lower risk of heart disease, etc.
- reduce triglycerides –> large amount = harden & thicken artery walls (stroke, etc.)
what are the applications of lipids?
- subcutaneous fats –> acts as a buoyancy aid & thermal insulation
- water proofing of hair and feathers –> oily secretions of sebaceous glands (skin of mammals) = water repellent
- electrical insulation –> myelin lipid in membranes of Schwann cells –> form sheaths around long fibres of nerve cells –> electrically isolates cell plasma membrane & facilitates conduction of nerve impulses there.
