B1 Flashcards

Question

saturated/monounsaturated/polyunsaturated fatty acid

Answer 1

no C=C/ 1 C=C/ many C=C

Answer 2

2 saturated, 1 unsaturated kinky cannot stack ontop of each other liquid @ room temp e.g. oils 3 saturated can stack ontop of each other solid @ room temp e.g. fat

Answer 3

- high ratio of C-H to C (fatty acid) so excellent energy soure - low mass to energy ratio- good storage molecule, much energy stored in a small volume- reduces mass animals need to carry around - large, non-polar so insoluble in water- does not affect water potential - release H2O when oxidised

Answer 4

differ from triglyceride- one fatty acid molecule replaced by phosophate molecule hydrophilic head, hydrophobic tail

Answer 5

- polar molecules- in aqueous environment, form hydrophobic bilayer within cell-surface membranes - hydrophobic heads hold surface of cell-surface membrane - can form glycolipids within cell surface membranes- cell recognition

Answer 6

add ethanpl to sample shake to dissole add water shake gently milky white emulsion = positive milky colour = due to any lipid being finely dispersed in water to form emulsion light is refracted as it passes oil-water so appears cloudy

Answer 7

reducing - grind with pestle + mortar - add water - filter out solid - add benedicts - gently heat with water bath - blue to brick red non reducing - if reducing = negative - new sample, add HCl - boil - add alkali to neutralise - add benedicts - heat gently - blue to brick red

Answer 8

filter out precipitate and dry weigh ppt the higher the mass, the more sugar present

Answer 9

condensation reaction loss of water between glycerol and fatty acid

Answer 10

long straight chains linked by many hydrogen bonds to form fibrils grouped to fibres provide strength to cell walls

Answer 11

insoluble- doesnt affect water potential helical- compact large molecule- cannot leave cell

Answer 12

polar molecules form hydrogen bonds with water molecules

Answer 13

large molecule consisting of thousands of carbon atoms joined together (polymers = molecules) formed by condensation reactions

Answer 14

acid hydrolysis of sucrose molecules releases the monomers a-glucose and b-fructose the monomers are reducing sugars give a positive result when heated with benedicts reagent

Answer 15

contain cellulose exerts inward pressure on cell contents prevents further influx of water therefore cells do not burst when HYDROSTATIC PRESSURE increases

Answer 16

both virtually insoluble they DO NOT ADD TO THE SOLUTE CONC in cells so water potential is not affected

Answer 17

particles of a substance that are not dissolved but dispersed in a volume of water

Answer 18

amino acids are the monomer which combine through condensation and formation of peptide bonds to form the polymer polypeptide polypeptides can combine to form proteins proteins have a FUNCTION

Answer 19

central (alpha) carbon atom attached to: - amino group (-NH2) - carboxyl group (-COOH) - -H atom - R group

Answer 20

-OH of carboxyl combines with -H of amino group of another amino acid

Answer 21

can internally transfer ions H from COOH --> NH2 net charge of 0

Answer 22

the amino acid sequence in its polypeptide chain this sequence determines its shape, properties, function

Answer 23

the shape which the polypeptide chain forms as a result of hydrogen bonding the linked aa possess -NH and -C=O on either side of peptide bond H of -NH has 8+, O of C=O has 8- (due to high electronegativity of O and N) these groups form hydrogen bonds shape : a-helix or B pleated sheet

Answer 24

due to the bending and twisting of the polypeptide helix into a compact structure disulfide, ionic, hydrogen bonds present, as well as hydrophobic interactions it is the 3D shape of a protein that is important in terms of its function it makes each protein distinctive and allows it to recogise/ be recognised by other molecules

Answer 25

combination of many different polypeptide chains and associated non protein prosthetic groups into a large, complex protein molecule (conjugated)

Answer 26

biruret test- detects peptide bonds - place sample in test tube - add equal volume NaOH - add few drops CuSO4 and mix blue to purple is positive

Answer 27

unbranched tightly wound tertiary structure twisted in second helix to make quaternary water insoluble physically tough parallel polypeptide chains in long fibres functions structural role + contractile

Answer 28

roughy spherical water soluble tertiary structure critical for function polypeptide chains folded into a spherical shape functions metabolic catalytic regulatory transport protective

Answer 29

enzymes are globular proteins that act as catalysts they alter the rate of a chemical reaction without undergoing a permanent change themelves

Answer 30

- the reactants must collide with sufficient energy to alter the arrangement of their atoms - the free energy of the products must be less than that of the substrates - activation energy must be reached

Answer 31

breaking bonds bringing molecules together

Answer 32

globular proteins specific 3D structure as a result of primary protein structure functional region called active site - the specific region of the enzyme where the substrate binds and catalysis takes place

Answer 33

the molecule on which the enzyme acts active site + enzyme are complementary shape forms enzyme-substrate complex substrate is held in active site by bonds that temporarily form between certain a.a in the active site and the groups on the substrate molecule

Answer 34

R-groups of amino acids face inside the active site - made up of +ve and -ve charges - bonds temporarily form between a.a. and substrate - helps substrate settle in active site

Answer 35

enzyme only catalyses reaction with substrates with complementary shapes

Answer 36

proximity of substrate enzyme changes shape substrate in active site enzyme puts strain on substrate distorts bonds in substrate lowers activation energy needed to break bonds

Answer 37

an enzyme only fits the shape of 1 specific substrate - the enzyme is highly specific and rigid

Answer 38

enzymes are not rigid structures - other molecules can bind to the enzyme, NOT on the active site (e.g. non competitive inhibitors) and alter the active site shape - enzymes are therefore flexible structures so: if an inhibitor binds to enzyme (not act. site), the active site shape distorts and the substrate cannot fit - therefore, the active site changes depending on bonding molecules to the enzyme

Answer 39

use its time course: rate = amount/time amount = mass or volume disappearance of substrate or formation of product

Answer 40

- lots of substrate, 0 product -easy for substrate to meet empty active sites -all active sites are filled at one time -amount of substrate decreases as its broken down -amount of product increases -becomes more difficult for substrate to come into contact with enzyme- fewer substrate molecules as broken down, and product molecules get in the way. -substrate molecules take longer to be broken down and rate of reaction slows -rate continues to slow as substrate concentration decreases -until substrate concentration is so low so that any more change its concentration cannot be measured. -until no substrate left so rate stops

Answer 41

tangent to curve

Answer 42

- increasing temperature increases kinetic energy of molecules they move around more rapidly and collide more often more enzyme substrate complexes formed so rate increases - increasing temperature further begins to cause hydrogen bonds to break- change in tertiary structure active site changes shape- substrate fits less easily - increasing temperature further (around 60 degrees) the enzyme is so disrupted that it completely denatures and stops working. denaturation is a permanent change- enzyme is no longer functional

Answer 43

although higher body temperature would increase the metabolic rate slightly advantages offset by additional energy that would be needed to maintain the higher temperatures other proteins, apart from enzymes, may be denatured at higher temperatures at higher temperatures, any further rise in temperatures e.g. during illness, may denature the enzymes

Answer 44

some animals e.g. birds have a normal body temperature of around 40 degrees because they have a high metabolic rate for the high energy requirement of flight

Answer 45

1. where it starts 2. where it peaks- optimum temp 3. where it goes down 4. where it ends

Answer 46

pH is a measure of H= conc each enzyme has optimum pH at a different pH than the optimum, the H bonds in the active site are broken- enzyme denatires change in pH also alters the charges on amino acids in the active site- so it is no longer complementary can also break ionic+hydrogen bonds in the tertiary structure so the active site changes shape

Answer 47

1. identify bonds 2. state effect on tertiary structure of active site 3. decrease in the number of enzyme substrate complexes forming loss of complimentary shapes 4. denaturation reduction of rate of reaction

Answer 48

as long as excess substrate, increase in enzyme conc leads to proportionate increase in rate of reaction graph initially shows proportionate increase - because there is more substrate than the enzyme's active sites can cope with - increasing enzyme concentration, some excess substrate can be acted upon so rate increases if substrate is limiting (i.e. not sufficient substrate to supply all active sites) any increase in enzyme conc will have no effect on rate rate will stabilize at constant level because available substrate is already being used as rapidly as it can be by existing enzyme molecules

Answer 49

if enzyme conc = fixed and substrate conc increased, rate increases in proportion - at low substrate conc, enzyme molecules have limited number of substrate molecules to collide with so active sites are not working at full capacity - as more substrate added, active sites gradually become filled, until max rate Vmax when substrate is in excess, rate levels off

Answer 50

a substance which reduces the activity of an enzyme, catalyst or reactant

Answer 51

substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity

Answer 52

competitive- bind to active site non competitive- bind to enzyme at a position other than the active site

Answer 53

- similar molecular shape to substrate allows them to occupy active site it is the difference between the concentrations of the inhibitor and substrate that determines the effect on enzyme activity if the substrate conc is increased, effect of inhibitor is reduced the inhibitor is NOT PERMANENTLY BOUND to the active site so when it leaves another molecule can take its place sooner or later, all substrate molecules will occupy an active site, but the greater the concentration of inhibitor, the longer this will take

Answer 54

attach to enzyme at binding site which isnt active site upon attachment, alters shape of enzyme and thus its active site so that it is no longer complementary to substrate a PERMANENT change to shape of enzyme as the substrate and inhibitor are not competing, increase in substrate concentration does not decrease effect of inhibitor eventually no enzyme substrate complexes formed

Answer 55

a series of reactions in which each step is catalysed by an enzyme each reaction is connected by their intermediates i.e. the product of one is the reactant of the next

Answer 56

the enzymes that control a pathway are often attached to the membrane of a cell organelle in a precise sequence. - in a metabolic pathway, the product of one reaction acts as a substrate for the next - by having the enzymes in an appropriate sequence, there is a greater change of each enzyme coming into contact with its substrate than if the enzymes were free in the organelle this is a more efficient means of producing the end product to keep a steady concentration of a particular chemical in a cell, the same chemical often acts as an inhibitor of an enzyme at the start of a reaction,

Answer 57

end product inhibits 1st enzyme if the concentration of end product increases above normal, there will be greater inhibition of 1st enzyme as a result, less product will be produced and its concentration will return to normal if the concentration of the end product falls below normal, there will be less to inhibit 1st enzyme so more product produced end product inhibition is normally non competitive

Answer 58

- the level of end product does not fluctuate with substrate non- competitive inhibitors occur at a site on the enzyme other than the active site- hence isnt affected by substrate concentration therefore in non-competitive inhibition, changes in the level of substrate do not affect the level of inhibitor, nor the level of end product competitive inhibition involves competition for active sites a change in the level of substrate would therefore affect how many end products molecules combine with active sites therefore the degree of inhibition would fluctuate and so would the level of end product.

B1 Flashcards

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