Biological Molecules

Question 1

how are polymers formed

Answer 1

monomers join a chemical bond by a condensation reaction which releases a molecule of water

Question 2

how are polymers broken down

Answer 2

hydrolysis, water is used to break down the chemical bond.

Question 3

monosaccharides: what type of sugar is glucose and what are its isomers

Answer 3

a hexose sugar, it has 6 carbon atoms in each molecule. alpha and beta glucose. alpha has the OH at the bottom and H at the top

Question 4

disaccharies: how are they formed and what bond is created

Answer 4

monosaccharides form a glycosidic bond by a condensation reaction and

Question 5

what monosaccharides form sucrose, lactose and maltose

Answer 5

sucrose = glucose+fructose lactose = glucose+galactose maltose = 2x alpha glucose

Question 6

what is the reducing sugar test

Answer 6

eg all monosaccharides + lactose, maltose. Add blue benedict’s reagent, boil in water bath, change in colour = reducing sugar. green - yellow - brick red.

Question 7

what is the non reducing sugar test

Answer 7

eg sucrose. add benedict’s reagent, hydrochloric acid and boil in a water bath. neutralise with sodium hydrocarbonate. add benedicts reagent again. blue = non-reducing sugar. this method can be used to get a reducing sugar out of a non-reducing sugar solution.

Question 8

why use a colorimeter when using benedict’s test

Answer 8

to test the concentration of precipitate. it does this by absorbing the remaining benedict’s reagent

Question 9

what is starch used for in plants

Answer 9

the alpha glucose polysaccharide is broken down by hydrolysis to make amylose and amylopectin to use for energy

Question 10

what is amylose used for

Answer 10

long, unbranched, coiled, compact, great for storage

Question 11

what is amylopectin use for

Answer 11

long, branched so enzymes break glycosidic bonds easily = easy glucose release

Question 12

what is good about starch

Answer 12

insoluble in water so doesn’t affect water potential which makes it good for storage

Question 13

what is the structure and function of gylcogen

Answer 13

excess glucose turns into glycogen. many branches of alpha glucose, compact and quick release of energy for mammals

Question 14

cellulose structure and function

Answer 14

long, unbranched, beta-glucose chains. cellulose chains joined by hydrogen bonds which form strong fibres called microfibrils = support in plant cell walls

Question 15

iodine test for starch

Answer 15

add iodine, blue/black = starch. brown/orange = no starch

Question 16

lipids: structure of triglycerides

Answer 16

one molecule of glycerol and 3 fatty acid molecules (a tail) called hydrocarbons. tail in hydrophobic, so insoluble in water. ester bonds formed between FA and glycerol by condensation reaction

Question 17

difference between un/saturated fatty acid

Answer 17

un = have double bonds between carbon atoms
sat = no double C bonds, is saturated with Hydrogen

Question 18

structure of a fatty acid

Answer 18

O = C - HO - R(variable hydrocarbon tail)

Question 19

structure of a phospholipid

Answer 19

found in cell membrane, 2 FA , 1 glycerol, 1 phosphate group (hydrophilic)

Question 20

properties of lipids

Answer 20

triglycerides = storage, insoluble, don't affect water potential
phospholipids = bilayer of cell membrane, not easy for water soluble molecules to pass through the hydrophobic centre layer

Question 21

emulsion test for lipids

Answer 21

shake sample with ethanol, pour into water, lipid shows as a milky emulsion above the water

Question 22

what are proteins made from

Answer 22

amino acids, 2x a.a = dipeptide 2+x a.a = polypeptide

Question 23

structure of a amino acids

Answer 23

carboxcylic acid, r group, amine group. theres only 20 amino acids, their r groups is the only difference

Question 24

how are di/polypeptides formed

Answer 24

condensation reaction forms a dipeptide bond. hydrolysis breaks this down

Question 25

primary structure vs secondary protein structure

Answer 25

primary = a.a in polypeptide chain, secondary = H bonds between a.a in chain, this makes it a alpha helix/beta pleated sheet

Question 26

tertiary vs quaternary structure

Answer 26

tertiary = coiled a.a chain, more H bonds and now ionic bonds form. Disulfide bridges form between 2 cysteine molecules quaternary = made of more than one polypeptide chain eg haemoglobin

Question 27

test for proteins

Answer 27

biurets test, add sodium hydroxide for alkalinity, copper (ll) sulfate. blue =no purple =yes

Question 28

what are enzymes used for

Answer 28

proteins. biological catalysts for metabolic reactions. their active site has a specific corresponding substrate molecule

Question 29

what is activation energy

Answer 29

energy for reaction to start, given off by heat, enzymes lower this thus increasing the rate of reaction

Question 30

name the 2 models of enzyme action

Answer 30

lock and key, induced fit is more accurate = substrate has to be specific to active site and morphs a.s into the correct shape

Question 31

how can you measure enzyme activity

Answer 31

how fast the product is made and how fast the substrate is being broken down

Question 32

factors affecting enzyme activity - increasing

Answer 32

temperature, pH, (until it denatures), substrate concentration, enzymes concentration (until there is surplus of both)

Question 33

difference between non and competitive inhibitors

Answer 33

non = bind to enzyme away from active site, changing its shape, substrate no longer fits
competitive = bind to active site which stops reaction