AQA A Level Biology

• monosaccharides• disaccharides• polysaccharides

• glucose• fructose• galactose

• maltose• lactose• sucrose

• cellulose• starch• glycogen

• commonly referred to as sugars• structural isomers• single carbohydrate molecules• general formula - (CH2O)n• ose = sugar e.g pentose(5), triose(3), hexose(6)

• when two monosaccharides join together—> bond formed = glycosidic bond• reaction is known as a condensation reaction

• a bond which it's formation involves the loss of a water molecule

• glucose + glucose = maltose + water• glucose + fructose = sucrose + water• glucose + galactose = lactose + water

• during digestion• reaction involves the breaking of a bond by reacting it with water• HYDROLYSIS REACTION

• glucose• fructose• maltose

• 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

• reducing sugar = brick red• not reducing = blue/ no colour change

benedicts

• alpha• beta

• alpha glucose hydroxyl group sticks below the ring• beta glucose hydroxyl group sticks above the ring (BUP)

monosaccharides joined together by many glycosidic bonds

a storage polysaccharide stored in starch grains

(C6H10O5)n

• amylose - loose helix unbranched helical chain of alpha glucose molecules• amylopectin - branched chain of alpha glucose

more branches = more ends to hydrolyse

• energy storage• insoluble - water potential is unaffected and so won't diffuse out of cells• compact• easily hydrolysed

alpha glucose (1-4 glycosidic bonds)

animals

• liver cells hydrolyse glycogen and release glucose into the blood• hormone glucagon and adrenaline• ONLY HAPPENS WHEN TRIGGERED BY HORMONE

muscle cells hydrolyse glycogen but use glucose within the cell to release energy for muscle contraction

• more branched than amylopectin• more ends to hydrolyse

• similar to starch• chains are shorter and have more branches• more compact than starch - a-glucose molecules can be hydrolysed faster

• main component of plant cell wall• made up of beta glucose• (C6H10O5)n• a polysaccharide• hydroxyl group sticks ABOVE the ring

• 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)

• cellulose molecular chains are grouped to form microfibrils• microfibrils are grouped to form fibres which provide more strength

• 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

• small, basic molecular unit- large molecules made of these

large complex molecules composed of long chains of monomers joined together

• amino acids- monosaccharides- nucleotides

• 2 molecules join together with the formation of a new chemical bond (glycosidic)- water molecule released when bond is formed

• breaks the chemical bond between monomers using a water molecule- opposite of condensation

• alpha glucose- beta glucose

condensation of alpha glucose

condensation of beta glucose

• test for starch- add iodine dissolved in potassium iodide solution to test the sample- starch present = BLACK- not present = orange/brown

3 fatty acids + glycerol

• triglycerides- phospholipids

• carboxylic acid (head)- hydrocarbon chain (tail)

all the bonds are used up

one double bond

2 or more double bonds

condensation of glycerol and 3 fatty acids

ester bond

3 water molecules

• in cell membranes- source of energy- waterproofing- insulation- protection

3 fatty acids + glycerol

• high ratio of energy storing carbon-hydrogen bonds to carbon atoms- low mass to energy ratio- insoluble in water- release water when oxidised

one of the fatty acid molecules is replaced by a phosphate molecule

• hydrophilic head-hydrophobic tail

hydrophilic heads are close to the water and hydrophobic tails are far away

• polar- heads help to hold at the surface of the membrane- allows glycolipids to be formed

1. add 2cm cubed sample to a clean test tube2. add 5cm cubed of ethanol3. shake thoroughly4. add 5cm cubed of water and shake again

cloudy white (emulsion) = lipid

• phospholipids- tryglycerides

saturated or unsaturated

• don't have any double bonds H H H H| | | |- C - C - C - C -| | | |H H H H

• at least one double bond

tertiary

• depends on folding go the protein- substrate has to be complementary to fit

• lower activation energy- catalysts that speed up rate of reaction without being used themselves

• substrate binds to form an enzyme-substrate complex- binding places stress on the bond causing the bond to break- products are released

• enzymes are specific- substrate will only fit the active site of one particular enzyme

• other molecules could bind to enzyme at other sites

• activity changed suggesting shape changemeant the enzyme's structure was flexible

allesteric site

• enzyme changes shape slightly to mould around the substrate

• explains how other molecules affect enzyme activity- explains how activation energy is lowered

• higher temp = molecules have more kinetic energy- molecules move faster- molecules collide more frequently- enzyme and substrate form an 'enzyme-catalysed reaction'

• more collisions = more enzyme-substrate complexes form- RATE OF REACTION INCREASES

slowly increase to optimum then decreases(falling curve) as a general curve

enzyme is denatured

• 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

enzyme is denatured

• change in ph alters charge on amino acid- substrate can no longer attach- enzyme-substrate complex cannot form

• 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

• 2x enzyme molecules- all substrate molecules can occupy an active site- rate of reaction doubles to maximum as all active sites are filled

• addition of enzyme molecules has no effect- active site all already full- no increase in rate of reaction

• too few substrate molecules to occupy all active sites- rate of reaction is only 1/2 maximum possible for number of enzyme molecules available

• 2x substrate molecules available- all active sites occupied- rate of reaction has doubled to its maximum as all active sites are filled

• addition of substrate molecules has no effect- active sites all already full- no increase in rate of reaction

steady increase then plato

• bind with the active site so the substrate cannot fit

initial rate is slower

very little reaction then plato so line is very low

• binds to allestiric site- binding changes shape of active site- enzyme-substrate complex cannot form

• 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

• primary structure determined by gene- if mutation occurs it could change the tertiary structure of the enzyme produced

• models of enzyme action have changed over time- enzymes catalase wide range of intracellular and extracellular reactions that determine structures and functions

catalase breaksdown hydrogen peroxide into water and oxygenmeasuring volume of oxygen produced can be used to work out how fast its given off

1. draw tangent at t=02. calculate gradient (change in y divided by change in x)

t = volume of product released by enzyme-controlled reaction at different tempsy axis = volume of product released in cm cubedx axis = time (s)

adenosine triphosphate

• building macromolecules- active transport- muscle contraction- secretion- activation of molecules