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Biology biomolecules suffering yo
General info
 Biological molecules that make up life are carbohydrates, lipids, proteins, nucleic
acids and they are ALL POLYMERS whoa boy
 Metabolism refers to all chemical processes that go down in a living organism (ana
is building molecules outa smaller units, cata is breaking molecules down into
smaller units)
 Monomer to Polymer reacton = CONDENSATION REACTION, water is released
(helpful for hydraton)
 Polymer to Monomer reacton = HYDROLYSIS REACTION, requires water and a
‘suitable’ enzyme
 Carbon atoms are rly versatle as they readily form bonds with each other and many
other atoms
 Means that most of the molecules in our body join the same way bc they’re all
carbon based
Monosaccharides
Made up of CARBON, HYDROGEN and OXYGEN only ~

 MONOSACCHARIDE (a sweet tastng, soluble sugar
unit)is the monomer of carbohydrates
 Eg glucose, galactose, fructose
 Can come in RING or LINEAR form
 Can have isomers with same formula but diferent ring
structures (eg, fructose and glucose) or one being a ring
and the other linear or two diferent linears whatever
 Hexose is 6, triose is three
 Glucose has two forms, alpha and beta
 THE HYDROGEN AND HYDROXYL GROUPS ARE SWITCHED AT CARBON ONE which is
hella important for how these two monomers form polymers, and the resultng
structure of the polysaccharides
 There are only two versions bc the tght ring
structure makes the two groups rotatng
around the carbon
impossible

 Monosaccharides form GLYCOSIDIC BONDS through condensaton reactons, water
is released

Disaccharides
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DISACCHARIDE: two monosaccharide units joined together via a glycosidic bond
Maltose= two glucose
Lactose= glucose and galactose
Sucrose= glucose and fructose (and is also non reducing btw)

Polysaccharides
POLYSACCHARIDE: Many monosaccharide units joined together via glycosidic bonds
Very large molecules, insoluble
Suitable for storage due to this
Orrrrrr structural support, eg cellulose
Many alpha glucose becomes starch
o Can be amylose, which is straight and unbranched
o Or amylopectn, branced
 Beta glucose becomes cellulose
o Cannot immediately form glycosidic bonds, so
every other monomer must fip
o This creates straight, unbranched, structural
fibres
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TESTING FOR SUGARS YO
o To test soluton, add an equal amount of benedicts reagent, shake, heat
strongly in a water bath for a few minutes
o A precipitate indicates reducing sugar
 Mention red brown as your go to posttive result
 Otherwise orange is medium levels of sugar present, yellow is low,
green is very low, blue is none ~
o If ya first test ts negative, add dtlute sodtum hydroxtde and heat the tube
again
o if afer this a precipitate is formed, it’s a non reducing sugar
 probs sucrose, but maybe trehalose
 can do a semi quantatve benedicts test by comparing colours with the precipitates
of solutons with known concentratons of sugar

 or use a colourimeter, give the colour a no
...
against known
concentraton of sugars and create a calibraton curve
 TEST FOR STARCH: Add iodine soluton, should go from blue black to red brown ~
Starch yo
o
o
o
o

Found in many parts of a plant in the form of small grains
Especially in seeds and storage organs
Made up of chains of alpha glucose
Amylose and amylopectn, branched and not
 Amylose is wound into a v tight cotl

Main role is in storage and its structure is suited for these
reasons
 Insoluble, does not afect water
potential or afect osmosts
 Large and tnsoluble, does not dtfuse out of cells
 Compact, lots can be stored tn a smol space
 When hydrolysed becomes Aglucose
 Easily transported
 Readily used in respiraton
 Amylopectn had many ends, each of which enzymes can act on SIMULTANEOUSLY :
0, meaning glucose monomers are released v quickly
Glycogen: found in animals and bacteria but never in plant cells (never
...
)
 Similar to starch but
o Shorter chains
o More highly branched
 Glycogen is the major carbohydrate storage product of animals
o But the mass is relatvely smol because fat is the main storage molecule of
animals
 Stored in smol granules, mainly in muscles and the liver
 Here’s why the structure rules okay
o Large and insoluble, doesn’t draw water into cells, does not difuse out of
cells
o Compact so much can be stored in small volumes
o More highly branched than starch

 IMPORTANT because this means more ends can be acted on at the
same tme by enzymes
 Aglucose can be released more rapidly

 V helpful in animals as animals move and use energy for muscle
contracton, much higher rate of metabolism than plants
BONJOUR tt’s cellulose
 Straight, unbranched chains
 Because alternate molecules have to fip, hydrogen
bonds can form between parallel, adjacent chains- cross
ltnkage
o Individually weak but collectvely a considerable
contributon to strengthening
 Cellulose molecules are grouped together to form mtcrofibrtls
o These are arranged in parallel groups called fibres
 Cellulose is major component of plant cell walls and provide rtgtdtty to the plant cell
o Stops cell burstng from osmotc pressure by exerting an tnward pressure
that stops any further tnfux of water
o Living plant cells are turgid, push against each other and make non woody
parts of the plant semi rigid
 Important to keep stem and leaves turgid for max SA for
photosynthesis
 Couldn’t do without cell wall stopptng the cells from bursting
 here’s why the structure ts v
...
Alcohols
Roles :0
 Cell membrane: phospholipids=
fexibility, allows the transfer of lipid
soluble material across but not water
soluble, allows diferent cells to have diferent environments, keeps
reactons separate
 Buoyancy
 Source of energy: when oxidised, lipids provide more than twice the energy
as same mass of carbohydrate, and also releases water which is SO
IMPORTANT FOR HYDRATION WOW
 Waterproofing: lipids are insoluble, can give plants and insects a waxy cutcle
that conserves water
o Mammals produce otly secretion from sebaceous gland tn sktn
 Insulation: fats are slow conductors of heat when stored beneath skin they
help retain body heat, also electrical insulaton in myelin sheath around
nerve cells
 Protection: ofen stored around delicate organs, eg, kidneys
Trtglycertdes
 Large and non polar
 Three faty acids make an ester bond with glycerol, formed by condensation
reacton duh
 Diferences in propertes is down to what faty acids there are
o 70 diferent
o All have carbonyl group with hydrocarbon chains atached
o If hydrocarbon chain has no double bonds, tt ts saturated as each carbon
atom ts attached to the max
...
of hydrogen atoms
o Monounsaturated, polyunsaturated
o Doubles bonds cause molecule to bend, cannot pack together so closely/
reduced density, more likely to be ltqutds at room temp
 Low mass to energy ratio: much energy in smol volume
o Antmals have less mass to carry as they move whtch ts good yo
 Large, polar, tnsoluble: they do not alter water potental

 Htgh H:O ratio, so water ts released when trtglycertdes are oxtdtsed
o V important, especially in the desert
Phospholtptds
One faty acid molecule of a triglyceride is replaced by a phosphate molecule (so, glycerol
atached to two faty acid molecules and one phosphate molecule)
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Hydrophobic faty acid tails which repel water
Hydrophilic phosphate heads which are atracted to water
Two ends that behave diferently- polar
Structure
o Polar, phospholipid molecules form a bilayer in aqueous environments
 Hydrophobtc barrter formed between the tnstde and the outstde of
the cell
 Self assembles due to the diferent ends being atracted/ repelled by
water
 No energy expended
 Allows diferent conditons to be established in and out of cell
o Structure allows them to form glycoltptds wtth carbohydrates on the CSM:
important for cell recogniton

Test for ltptds yo
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To 2cm^3 of sample, add 5cm^3 of ethanol
Shake tube to dissolve any lipid
Add 5cm^3 of water and shake gently
Cloudy white emulsion= lipids
Control wtth water should rematn clear



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