module 2: biological molecules

Question 1

why is water needed

Answer 1

reactant in chemical reactions
a solvent
transports substances
temperature control- high SHC and high LHOE
habitat- less dense when freezes

Question 2

structure of water

Answer 2

1 oxygen 2 hydrogen
polar molecule- negative O positive H
hydrogen bonding

Question 3

properties of water

Answer 3

high specific heat capacity
high latent heat of evaporation
polarity causing cohesion
good solvent
less dense when solid

Question 4

structure of alpha glucose

Answer 4

hexose monosaccharide
ADDUD

Question 5

structure of beta glucose

Answer 5

hexose monosaccharide
BUDUD

Question 6

structure of ribose

Answer 6

pentose monosaccaride
RUDD

Question 7

what are the disaccharides

Answer 7

maltose- a glucose + a glucose
sucrose- a glucose + fructose
lactose- b glucose + galactose

Question 8

what is starch made from

Answer 8

amylose
amylopectin

Question 9

describe amylose

Answer 9

long unbranched chain of alpha glucose
coiled structure
compact so good for storage

Question 10

describe amylopectin

Answer 10

long branched chain of alpha glucose
side branches allow enzymes to break down glycosidic bonds easily for quick energy

Question 11

describe glycogen

Answer 11

main energy storage in animals
long branched chain of alpha glucose
compact

Question 12

describe cellulose

Answer 12

long unbranched chain of beta glucose
straight cellulose chains
chains held by hydrogen bonds
structural support

Question 13

what are triglycerides

Answer 13

energy storage in plants and animals
1 glycerol
3 hydrocarbon fatty acid tails
synthesised by ester bond
hydrophobic heads hydrophilic tails

Question 14

what is the difference between saturated and unsaturated fatty acids

Answer 14

saturated- don’t contain double carbon bonds
unsaturated- have double carbon bonds

Question 15

structure and function of phospholipids

Answer 15

1 glycerol, 1 phosphate groups 2 fatty acids
found in cell membranes- phospholipid bilayer
heads are hydrophilic
tails hydrophobic
makes centre of bilayer hydrophobic acting as a barrier

Question 16

structure and function of cholesterol

Answer 16

hydrocarbon ring structure with hydrocarbon tail
has polar group attached
regulate fluidity of membrane
small and flat
at high temps they pack together causing rigidity

Question 17

what are proteins made from

Answer 17

long chains of amino acids
one or more polypeptides

Question 18

structure of an amino acid

Answer 18

central c
carboxyl group
amino group
variable group
joined by peptide bonds

Question 19

what is primary structure

Answer 19

the sequence of amino acids in polypeptide chain

Question 20

what is secondary structure

Answer 20

coiled alpha helix or folded beta pleated sheet caused by formation of hydrogen bonds

Question 21

what is tertiary structure

Answer 21

coil of folding of secondary structure forming 3D structure
uses ionic bonds, disulphide bonds, hydrophobic and hydrophilic interactions
hydrogen bonds

Question 22

what is quaternary structure

Answer 22

several polypeptide chains held together by bonds
final 3D structure

Question 23

describe globular proteins

Answer 23

soluble so easily transported
round and compact

Question 24

examples and description of globular proteins

Answer 24

haemoglobin- conducted protein containing iron prosthetic group
insulin- hormone consisting of 2 polypeptide chains
amylase- enzyme that brakes down starch

Question 25

describe fibrous proteins

Answer 25

insoluble
strong and rope like
unreactive

Question 26

examples and description of fibrous proteins

Answer 26

collagen- in connective tissue
keratin- in hair, skin, nails
elastin- is elastic connective tissue, recoils

Question 27

what are inorganic ions

Answer 27

an ion that has electrical charge
positive- cation
negative- anion
don’t contain carbon

Question 28

test for reducing sugars

Answer 28

Benedict’s
add Benedict’s reagent to sample and heat it in water bath
if positive test goes from blue to green to yellow to orange to brick red

Question 29

test for non-reducing sugars

Answer 29

add dilute hydrochloric acid to new sample and heat
neutralise with sodium hydrogencarbonate
carry out normal Benedict’s test

Question 30

test for starch

Answer 30

iodine- if starch present it will turn brown-orange to blue-black

Question 31

test for proteins

Answer 31

biuret- add sodium hydroxide to sample then copper sulphate
if protein present- blue to purple

Question 32

test for lipids

Answer 32

emulsion test- shake sample with ethanol and pour into water
if lipid present- clear to milky