biological molecules Flashcards
1
Q
condensation reaction
A
when 2 monomers join and a water molecule is removed
2
Q
hydrolysis
A
water molecules are added in the process of breaking down polymers into monomers
3
Q
bond formed in condensation reaction
A
glycosidic
4
Q
isomer
A
ions or molecules with identical formulae but different structures, not necessarily sharing the same properties
5
Q
carbohydrate monomer
A
monosaccharide
6
Q
carbohydrate polymer
A
polysaccharide
7
Q
protein monomer
A
amino acid
8
Q
protein polymer
A
polypeptide
9
Q
nucleic acid monomer
A
nucleotides
10
Q
nucleic acid polymer
A
ribonucleic acid / DNA
11
Q
glucose + glucose =
A
maltose
12
Q
glucose + fructose =
A
sucrose
13
Q
glucose + galactose =
A
lactose
14
Q
how is starch specialised for energy storage (5)
A
- insoluble - doesn’t affect water potential/osmosis
- large - doesn’t diffuse out of cells
- compact - lots stored in a small space
- forms α glucose which is easily transported and used in respiration
- branched - has many ends which can be acted on by enzymes, releasing glucose monomers rapidly
15
Q
glycogen found in…
A
animals and bacteria
16
Q
structure of glycogen compared to starch
A
shorter chains, more highly branched
17
Q
structural adaptations of glycogen (4)
A
- insoluble - doesn’t affect osmosis/water potential
- insoluble - doesn’t diffuse out of cells
- compact
- highly branched - increased enzyme activity = faster break down which is important to animals with a high metabolic rate
18
Q
type of glucose glycogen and starch are made up of
A
α glucose
19
Q
glucose type cellulose is made up of
A
β glucose
20
Q
structure of cellulose
A
straight, unbranching chains, which run parallel to each other, with cross-linking hydrogen bonds between adjacent chains
21
Q
function of hydrogen bonds in cellulose
A
adds strength to the molecule which provides rigidity for the plant
22
Q
how is cellulose specialised for structural function (3)
A
- molecules made up of β glucose = straight unbranching chains
- collective strengthening effect of cross-linkage hydrogen bonds
- molecules group to form microfibrils, which group to form fibres which add more strength
23
Q
shared characteristics of lipids (4)
A
- contain carbon, hydrogen, oxygen
- proportion of oxygen to hydrogen and carbon is smaller then in carbohydrates
- insoluble in water
- soluble in organic solvents (eg. alcohols and acetone)
24
Q
main lipid groups
A
trigycerides (fats and oils)
phospholipids (main component of cell membrane)
25
roles of lipids (5)
- cell membrane - flexible, control transfer of lipid soluble substances across
- source of energy
- waterproofing - as insoluble in water
- insulation - heat and electrical in myelin sheath around nerve cells
- protection - stored after around delicate organs
26
structure of triglycerides
3 fatty acids , 1 glycerol
27
Test for non-reducing sugar
- test for reducing sugar
- add 2cm³ food sample to 2cm³ HCl
- water bath for 5 mins (hydrolyse any disaccharides)
- add sodium hydrocarbonate slowly (neutralise as Benedict's doesnt work in acidic)
- check alkaline using pH paper
- retest with Benedict's
28
carbohydrate test
- add 2 drops iodine into tube
| - yellow -> blue/black if present
29
pentose sugar
5 carbon atoms
30
pentose sugars examples (2)
ribose
| deoxyribose
31
hexose sugar
6 carbon atoms
32
starch made from
- amylose
| - amylopectin
33
why is starch compact and insoluble?
because of the combined properties/structure of amylopectin and amylose
34
structure of amylose
long straight chain that coils
35
structure of amylopectin
long and branched
36
why are triglycerides hydrophobic
they are non polar (there is no uneven distribution of charge within the molecule) meaning they don't for hydrogen bonds with water molecules ∴ don't dissolve in water
37
general formula of a saturated fatty acid
CH3(CH2)nCOOH
38
main lipid tests
- sudan III
- emulsion test
- grease spot test
39
emulsion test
- 2cm³ into test tube containing 2cm³ absolute ethanol
- dissolve by shaking vigorously
- add equal volume of cold water
- cloudy white suspension forms in presence of lipid
40
sudan III test
- 2cm³ sample to 2cm³ water
- add a few drops of Sudan III and shake
- red-stained oil layer separates on surface of water which remains uncoloured
41
grease spot test
- drop of sample on paper
- allow to evaporate
- permanent transparent spot on paper
42
primary protein structure
specific sequence of amino acids in the protein joined by peptide bonds
43
secondary protein structure
polypeptide chains fold into α helixor β pleated sheet - maintained by hydrogen bonds
44
tertiary protein structure
protein folds up because various points on the secondary are attracted to one another - bonds = disulfide bridges, hydrogen bonds, ionic bonds
45
quaternary protein structure
several units of tertiary bonds with H bonds and ionic bonds to form a functional protein, may also be prosthetic groups added
46
prosthetic group
non-protein group
47
properties/features of water (5)
- cohesion - high surface tension which holds cells together
- metabolite - in condensation, hydrolysis, photosynthesis and respiration reactions
- a solvent - a medium for diffusion, allowing the transport of dissolved substances
- high SHC - buffers change in temperature
- high heat of vaporisation - provides cooling effect when evaporated (sweat) - large amount of heat lost with minimal water
48
activation energy
the energy required to be supplied to the reactants to overcome their inter-molecular repulsive forces so that they can undergo a chemical reaction
49
induced fit model of enzyme action
when the substrates combines with the enzyme and the enzyme changes shape, forcing the substrate molecules to combine/putting strain on the molecule, causing a particular bond to break - when substrate is released, enzyme returns to normal shape
50
lock and key model of enzyme action
substrate drawn into a closely matching cleft on enzyme molecule
51
competitive inhibitor
has a shape resembling shape of substrate - forms temporary enzyme-inhibitor complexes, blocking substrate
52
non-competitive inhibitor
binds to enzyme at another site to the active site, changing tertiary structure, ∴ active site shape changes, ∴ no EZ complex's made
53
how does ATP release energy
hydrolysis of phosphate bond between 3rd and 2nd phosphate groups by ATP hydrolase - breaking bond releases energy
54
limitations of lock and key model
- assumes structure is rigid, which isn't correct as observations show the activity of the enzyme can be altered by other molecules binding to it changing its shape ∴ structure = flexible
55
effect of pH on enzyme activity
- changes charges of amino acids in active site, meaning no E/Z complexes can be formed
- if dramatic enough, may break bonds in tertiary structure, meaning active site shape changes
56
describe protein structure [3]
- polymer of amino acids
- joined by peptide bonds
- made in condensation reactions
