1. Biological Molecules

Created by

owen leighton

Cards (80)

what is a condensation reaction?
a reaction where a chemical bond is formed between two molecules, using up a water molecule
what is a hydrolysis reaction?
the breaking of chemical bonds, and the addition of a water molecule
what is metabolism? 
all the chemical processes that take place in living organisms
what is a carbohydrate?
an organic molecule which contains carbon, hydrogen and oxygen
what is used to test for reducing sugars?
benedict's reagent
what is the positive test in a benedict's test?
an insoluble red precipitate of copper(I) oxide is formed
what are the steps involved in benedict's test?
1. add 2cm3 of the sample to a test tube
2. add an equal volume of benedict's reagent
3. heat the mixture in a gently boiling water bath for 5 minutes
what does two glucose joined together formed?
maltose
what does glucose and fructose joined together form?
sucrose
what does glucose joined to galactose form?
lactose
what bond is formed between two monosaccharides?
glycosidic bond
what test is used for a non-reducing sugar?
benedict's test
what change must be done to test for a non-reducing sugar?
the sample must first be hydrolysed into its monosaccharides and then perform benedict's test
what must you do after it has been hydrolysed?
slowly add some sodium hydrogencarbonate solution to neutralise
what will the benedict's test do after the disaccharide has been hydrolysed and a non-reducing sugar is present?
turn orange-brown
what is starch? 
a polysaccharide which is the storage form of glucose in plants, found as small granules or grains
what is the test for starch?
iodine test
what are the steps in the iodine test?
1. place 2cm3 of sample in a test tube
2. add two drops of iodine solution and shake/stir
3. if starch is present, the sample will turn blue-black
how is a-glucose arranged in starch?
a helix
why is it important that starch is insoluble?
it won't affect water potential, and so water won't enter cells by osmosis which would cause swelling
how can chromatography be used to separate monosaccharides?
a chromatogram in paper chromatography
what is amylose? 
unbranched helix shape with 1,4 glycosidic bonds, and is compact and accounts for 10-30% of starch
what is amylopectin? 
1,4 glycosidic bonds cross linked with 1,6 glycosidic bonds and branches result in terminal a-glucose molecules which are easily hydrolysed, accounts for 70-90% of starch
what is glycogen? 
glucose storage compound in animals and fungi
which areas have high concentrations of glycogen and visible granules?
liver and muscle cells
why is glycogen more compact than amylopectin?
glycogen is more branched
what is cellulose? 
the polymer that is involved in the cell walls of plant cells
what is the structure of cellulose? 
long, straight chain of b-glucose subunits with 1,4 glycosidic bonds
what gives cellulose its strength?
hydrogen bonds
what are microfibrils? 
many cellulose chains held together by hydrogen bonds
what allows water and solutes to leave or reach the cell surface membrane in plant cells?
cellulose fibres being freely permeable
what are the four main roles of lipids?
source of energy, waterproofing, insulation and protection
in what state can lipids provide more than twice the energy as the same mass of carbohydrate?
oxidised
why are lipids good for waterproofing?
they are insoluble in water
why are lipids good at helping the body to retain heat?
fats are slow conductors of heat
why are triglycerides an excellent source of energy?
high ratio of energy storing carbon-hydrogen bonds to carbon atoms
why are triglycerides good storage molecules?
low mass to energy ratio so more energy can be stored in a smaller volume
why are triglycerides insoluble in water?
they are large, non-polar molecules
why are triglycerides a good source of water?
they have a high ratio of hydrogen to carbon atoms, so when oxidised release water
what are the two parts of a phospholipid?
hydrophilic head and a hydrophobic tail