Studied by 33 peoplewhat are the 3 types of carbohydrate?
• monosaccharides• disaccharides• polysaccharides
give some examples of monosaccharides
• glucose• fructose• galactose
give some examples of disaccharides
• maltose• lactose• sucrose
give some examples of polysaccharides
• cellulose• starch• glycogen
describe monosaccharides
• commonly referred to as sugars• structural isomers• single carbohydrate molecules• general formula - (CH2O)n• ose = sugar e.g pentose(5), triose(3), hexose(6)
describe disaccharides
• when two monosaccharides join together—> bond formed = glycosidic bond• reaction is known as a condensation reaction
what is a glycosidic bond?
• a bond which it's formation involves the loss of a water molecule
give some disaccharide formation examples
• glucose + glucose = maltose + water• glucose + fructose = sucrose + water• glucose + galactose = lactose + water
explain how disaccharides are broken down
• during digestion• reaction involves the breaking of a bond by reacting it with water• HYDROLYSIS REACTION
give some examples of reducing sugars
• glucose• fructose• maltose
describe the benedicts test
• place the sugars into test tubes (&control)• add benedicts to all the test tubes• heat a water bath and add test tubes for 5 mins
what are the results of the benedicts test
• reducing sugar = brick red• not reducing = blue/ no colour change
what is the test for reducing sugars?
benedicts
what are the two forms of glucose?
• alpha• beta
what are the differences between alpha and beta glucose?
• alpha glucose hydroxyl group sticks below the ring• beta glucose hydroxyl group sticks above the ring (BUP)
what is a polysaccharide?
monosaccharides joined together by many glycosidic bonds
what is starch?
a storage polysaccharide stored in starch grains
what is starch's general formula
(C6H10O5)n
outline the two different types of starch
• amylose - loose helix unbranched helical chain of alpha glucose molecules• amylopectin - branched chain of alpha glucose
why is more branches a benefit?
more branches = more ends to hydrolyse
how is the structure of starch linked to it's function?
• energy storage• insoluble - water potential is unaffected and so won't diffuse out of cells• compact• easily hydrolysed
what type of glucose is glycogen made up of?
alpha glucose (1-4 glycosidic bonds)
where is glycogen found
animals
how is glycogen used in liver cells?
• liver cells hydrolyse glycogen and release glucose into the blood• hormone glucagon and adrenaline• ONLY HAPPENS WHEN TRIGGERED BY HORMONE
how do muscle cells use glycogen?
muscle cells hydrolyse glycogen but use glucose within the cell to release energy for muscle contraction
why is glycogen being more branches a benefit?
• more branched than amylopectin• more ends to hydrolyse
how is glycogen structure is related to its function?
• similar to starch• chains are shorter and have more branches• more compact than starch - a-glucose molecules can be hydrolysed faster
outline cellulose
• main component of plant cell wall• made up of beta glucose• (C6H10O5)n• a polysaccharide• hydroxyl group sticks ABOVE the ring
what are the functions of cellulose?
• main component of plan cell walls as it provides rigidness to the plant cell• prevents cell bursting via osmosis - by exerting an inward pressure that stops any further influx of water—> makes the plant tug it so leaves and stems are upright (v important)
how does cellulose provide strength?
• cellulose molecular chains are grouped to form microfibrils• microfibrils are grouped to form fibres which provide more strength
outline the structure of cellulose
• contains straight unbranched chains that run parallel to each other—> this allows hydrogen bonds to form cross linkages between adjacent chains• bonded together by b-glycosidic bonding
what is a monomer?
small, basic molecular unit- large molecules made of these
what is a polymer?
large complex molecules composed of long chains of monomers joined together
give some examples of monomers
amino acids- monosaccharides- nucleotides
what is a condensation reaction?
2 molecules join together with the formation of a new chemical bond (glycosidic)- water molecule released when bond is formed
what is a hydrolysis reaction?
breaks the chemical bond between monomers using a water molecule- opposite of condensation
what are glucose's 2 isomers?
alpha glucose- beta glucose
how are glycogen and starch formed?
condensation of alpha glucose
how is cellulose formed?
condensation of beta glucose
outline the iodine test
test for starch- add iodine dissolved in potassium iodide solution to test the sample- starch present = BLACK- not present = orange/brown
what are triglycerides formed of?
3 fatty acids + glycerol
what are the main groups of lipids?
triglycerides- phospholipids
what are fatty acids made up of?
carboxylic acid (head)- hydrocarbon chain (tail)
what does 'saturated' mean?
all the bonds are used up
what does 'monounsaturated' mean?
one double bond
what does 'polyunsaturated' mean?
2 or more double bonds
how are triglycerides formed?
condensation of glycerol and 3 fatty acids
what bond is formed in the formation of a triglyceride?
ester bond
what molecules are formed in the formation of a triglyceride?
3 water molecules
what are the roles of lipids?
in cell membranes- source of energy- waterproofing- insulation- protection
what does the hydrolysis of a triglyceride produce?
3 fatty acids + glycerol
how is the structure of triglycerides related to its function?
high ratio of energy storing carbon-hydrogen bonds to carbon atoms- low mass to energy ratio- insoluble in water- release water when oxidised
how are phospholipids different to triglycerides?
one of the fatty acid molecules is replaced by a phosphate molecule
what are phospholipids made up of?
hydrophilic head-hydrophobic tail
how do phospholipids position themselves in water?
hydrophilic heads are close to the water and hydrophobic tails are far away
how is the structure of phospholipids related to its structure?
polar- heads help to hold at the surface of the membrane- allows glycolipids to be formed
what is the test for lipids?
add 2cm cubed sample to a clean test tube2. add 5cm cubed of ethanol3. shake thoroughly4. add 5cm cubed of water and shake again
what is the results for the lipid test?
cloudy white (emulsion) = lipid
what are the 2 groups of lipids?
phospholipids- tryglycerides
what two states can the R group of a fatty acid be in?
saturated or unsaturated
saturated fatty acid structure
don't have any double bonds H H H H| | | |- C - C - C - C -| | | |H H H H
unsaturated fatty acid structure
at least one double bond
H H H H| | | |- C - C - C = C - C| | | |H H H H
what type of structure does an enzyme have?
tertiary
outline the 'active site'
depends on folding go the protein- substrate has to be complementary to fit
how do enzymes work?
lower activation energy- catalysts that speed up rate of reaction without being used themselves
describe general enzyme action
substrate binds to form an enzyme-substrate complex- binding places stress on the bond causing the bond to break- products are released
outline the 'lock and key' theory
enzymes are specific- substrate will only fit the active site of one particular enzyme
what are some limitations of the lock and key theory
other molecules could bind to enzyme at other sites
what happened when other molecules bind to enzymes at other sites?
activity changed suggesting shape changemeant the enzyme's structure was flexible
what is another name for alternate active sites?
allesteric site
outline the 'induced fit' model?
enzyme changes shape slightly to mould around the substrate
how is the 'induced fit' model a better explanation of enzyme activity?
explains how other molecules affect enzyme activity- explains how activation energy is lowered
how does temperature effect enzyme action?
higher temp = molecules have more kinetic energy- molecules move faster- molecules collide more frequently- enzyme and substrate form an 'enzyme-catalysed reaction'
what does more collision due to the higher temperature mean?
more collisions = more enzyme-substrate complexes form- RATE OF REACTION INCREASES
what does the temperature rate of reaction graph look like?
slowly increase to optimum then decreases(falling curve) as a general curve
what happens if the temperature is too high?
enzyme is denatured
what effect does temperature have on the enzyme itself?
temp causes hydrogen and other bonds to break which alters the shape of the enzyme- substrate fits less easily at first slowing the rate of reaction
what happens if the ph on an enzyme changes too much?
enzyme is denatured
how does ph affect how an enzyme works?
change in ph alters charge on amino acid- substrate can no longer attach- enzyme-substrate complex cannot form
what is the effect on the rate of reaction at low enzyme concentration?
too few enzyme molecules to allow all substrate molecules to find an active site at one time- rate of reaction only 1/2 maximum possible for number of substrate molecules available
what is the effect on the rate of reaction at medium enzyme concentration?
2x enzyme molecules- all substrate molecules can occupy an active site- rate of reaction doubles to maximum as all active sites are filled
what is the effect on the rate of reaction at high enzyme concentration?
addition of enzyme molecules has no effect- active site all already full- no increase in rate of reaction
what is the effect on the rate of enzyme action at low substrate concentration?
too few substrate molecules to occupy all active sites- rate of reaction is only 1/2 maximum possible for number of enzyme molecules available
what is the effect on the rate of enzyme action at medium substrate concentration?
2x substrate molecules available- all active sites occupied- rate of reaction has doubled to its maximum as all active sites are filled
what is the effect on the rate of enzyme action at high substrate concentration?
addition of substrate molecules has no effect- active sites all already full- no increase in rate of reaction
what do the concentration graphs look like?
steady increase then plato
how do competitive inhibitors work?
bind with the active site so the substrate cannot fit
what effect do competitive inhibitors have on the rate of reaction?
initial rate is slower
what effect do non-competitive inhibitors have on the rate of reaction?
very little reaction then plato so line is very low
how do non-competitive inhibitors work?
binds to allestiric site- binding changes shape of active site- enzyme-substrate complex cannot form
enzyme properties related to their tertiary structure
very specific- only one complementary substrate will fit- active site determined by tertiary structure- different enzyme = different tertiary structure = differed shaped active site- if tertiary structure is altered the shape of the active site will change- pH or temp can alter tertiary structure
how can a mutation alter tertiarty structure
primary structure determined by gene- if mutation occurs it could change the tertiary structure of the enzyme produced
what should be appreciated about enzymes?
models of enzyme action have changed over time- enzymes catalase wide range of intracellular and extracellular reactions that determine structures and functions
investigation into the effect of a named variable on the rate of an enzyme controlled reaction rp1
catalase breaksdown hydrogen peroxide into water and oxygenmeasuring volume of oxygen produced can be used to work out how fast its given off
boiling tubes with same vol and conc of hydrogen peroxide set up2. place measuring cylinder upside down in water bath with deliver tube coming out into the boiling tube3. put each boiling tube in water to set temp4. use pipette to add same volume of conc of catalase to each5. reattach bung6. use stopwatch to record how much oxygen is produced7. repeat and calculate average rate of reaction
how to use a tangent to calculate initial rate of reaction
draw tangent at t=02. calculate gradient (change in y divided by change in x)
enzyme controlled reaction title and axis labels
t = volume of product released by enzyme-controlled reaction at different tempsy axis = volume of product released in cm cubedx axis = time (s)
what does ATP stand for?
adenosine triphosphate
what energy-requiring processes is ATP used in?
building macromolecules- active transport- muscle contraction- secretion- activation of molecules
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