Biological Molecules
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- Created by: elliebisseker
- Created on: 04-10-17 16:45
Carbohydrates
- sugars
- monosaccharides, disaccharides and polysaccharides
- CH20 (general formula)
- carbon, hydrogen & oxygen
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Monosaccharides
- all soluble in water
- single, simple sugars
- general formula C6H12O6
- isomers=same chemical formula but different arrangements of structure
- GLUCOSE
- GALACTOSE
- FRUCTOSE
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Glucose
- monosaccharide
- isomer
- monomer
- hexose
- major energy source of most cells
- highly soluble
- main form that carbohydrates are transported around the body in
- ring structure formed to become more stable
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Alpha Glucose
- OH is AWAY
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Beta Glucose
- OH is aBove
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Beta Glucose
- OH is aBove
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Beta Glucose
- OH is aBove
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Fructose
- in fruit
- slimming foods- sweeter than glucose
- hexose
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Galactose
- not as soluble
- important role in production of glycolipids and glycoproteins
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Disaccharides
- double sugars
- polymer
- condensation reactions form them - makes water
- hydrolysis reactions break them down- adds water
- general formula C12H22011
- sweet, white, crystalline
- soluble in water
glucose+glucose=maltose+H2O......germinating seeds
glucose+fructose=sucrose+H2O......add to drinks
glucose+galactose=lactose+H2O.....milk
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Condensation reaction
-forms glycosidic bond
-eg. maltose and water formed from a-glucose and b-glucose; a-1-4 glycosidic bond
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Hydrolysis Reaction
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Reducing and Non-reducing
Reducing:maltose, lactose
Non-reducing:sucrose
TEST
- need to be able to provide electrons to reduce the Cu2+
- forms red Cu+ precipitate
- For NON-reducing...
- Add acid to the new sample to hydrolse it; neutralise it and add more Benedicts
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Test for starch
- add iodine in potassium iodide solution
- blue-black colour=starch present
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Starch
- polysaccharide
- long-term storage in plants ONLY
- used overnight for energy
- seeds and tubers
- exists as amylopectin and amylose
- number of H2O molecules formed= number of monomers-1
- condensation reactions of a-glucose
- hydrolysed by amylase enzyme
- does not have any osmotic affects
- cannot diffuse out of cells
- compact
- easy to transport a-glucose
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Amylose
- homo polysaccharide
- unbranched chain of a-glucose
- hydrogen bonds wind it into a tight coil
- OH groups on inside= insoluble in water
- a-1-4 glycosidic bonds
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Amylopectin
- homo polysaccharide
- a-1-4 glycosidic and a-1-6 glycosidic bonds
- a-1-6 causes kinks and branches
- denser, more efficient
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Glycogen
- main energy storage in animals
- a-glucose ; a-1-4 gylcosidic bonds and a-1-6 glycosidic bonds
- a-1-4 cause straight chains with lots of ends where glycogen can be hydrolysed
- a-1-6 more branching more access to glycogen and more compact
- used in liver and muscles
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Cellulose Structure
- b-glucose ONLY, every second one inverted to make sure that OH molecules are aligned
- forms plant cell walls
- tough, insoluble, fibrous
- b-1-1 glycosidic bonding
- forms straight chains which lie parallel and hydrogen bonds form between and around them
- 60-70 chains=microfibril
- 400 microfibrils=macrofibrils
- high tensile strength
- difiicult to digest; need specific enzymes
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Functions of cellulose
- provide a skeleton
- allow turgidness of cells without bursting
- protects due to criss-cross
- permeable to only specific ions
- further enforced by waxes like cutin and suberin to make it waterproof
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Triglycerides
- carbon, hydrogen and oxygen
- fats and oils
- compounds
- condensation reaction between backbone of glycerol and 3 fatty acids with ester bonds
- 70 types
- saturated, monounsaturated and polyunsaturated
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Glycerol
- OH groups lost to water in condensation so they are non polar, insoluble and hydrophobic
- no osmotic effects on cells
- cannot easily pass through membranes
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Saturated Fatty Acids
- RCOOH
- all carbons bonded to hydrogen
- -COOH group is the ester
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Unsaturated Fatty Acid
- made by plants, oils at room temp
- kink from double bond
- possible to join more hydrogens
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Fatty Acids Uses
- energy stores in plants and animals- used once released via respiration, more energy per joule than carbohydrates
- adipose tissue (beneath skin) heat insulator adn low density therefore buoyancy aid
- plant seeds used in germination
- insoluble in water , no uneven distribution of charges, non polar, hydrophobic
- no osmotic effects on cells
- cannot easily pass through membranes too large
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Phospholipids
- backbone of glycerol
- 2 fatty acids=hydrophobic tails
- phosphate group= polar (-), hydrophillic head
- form micelles and bilayers
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Test for lipids
- shake substance with ethanol- does dissolve lipids
- gently pour into test tube of water- fats will seperate out
- emulsion formed of fats, lipids prevent light getting through
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Proteins
- polymers of many amino acis monomers joined together in long chains
- 20 amino acids
- eg of proteins// hormones, enzymes, recerptors...
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Amino Acids
- amino group NH2 accepts H+ ions to become NH3+
- carboxyl group produces H+ when dissolved in water, leaves a -ve COO-
- polar molecule
- r group = side chain for properties, eg glycine=H, alanine=CH3, cysteine=CH2SH
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Primary protein structure
- unique sequence of amino acids that makes a protein o rpolypeptide chain
- condensation reactions of amino acids to form a peptide bond per amino acid
- protein is one or more entwined polypeptide chain
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Secondary protein structure
- forms the chains into a-helix or b-pleated sheet
- a-helix= spiral, held by hydrogen bonds formed between H atom of amine group and O atom from carboxyl group of other amino acid
- happens after synthesis
- 2D
- good shape and stability
- helix= keratin
- sheet=fibroin in silk- antiparallel chains
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Tertiary protein structure
- polypeptide chains fold again
- complex 3D shapes
- held by hydrogen bonds, ionic bonds, and disulfide bridges
- sequence of amino acids determines where bonds can form
- determines the function
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Quaternary Structure
- one or more polypeptide chains
- haemoglobin
- can have other substances integrated
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Globular protein
- ball-shaped molecule
- soluble in water
- many r groups containing hydrophillic side chains on outside of ball which interact with water
- involved in metabolic reaction
- haemoglobin
- insulin and all enzymes
- shape allows them to form bonds with proteins in membrane of liver cells that are complimentary, triggers a sequence when bonded
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Fibrous proteins
- long, thin molcules
- chains of amino acids with regular hydrogen bond pattern, coil into helices, form fillaments, very strong and held by disulfide bridges
- structural roles
- not soluble in H2O
- keratin
- collagen- bound in criss cross in eye for transparancy and rigidness
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Test for peptide bonds
- add biuret reagent
- mix gently
- turns lilac when present
- control test with water
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