Biological Molecules

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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
    Image result for alpha glucose
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Beta Glucose

  • OH is aBove
    Image result for alpha glucose (http://biologyatsandringham.pbworks.com/f/1273011388/beta%20glucpse.jpg)
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Beta Glucose

  • OH is aBove
    Image result for alpha glucose (http://biologyatsandringham.pbworks.com/f/1273011388/beta%20glucpse.jpg)
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Beta Glucose

  • OH is aBove
    Image result for alpha glucose (http://biologyatsandringham.pbworks.com/f/1273011388/beta%20glucpse.jpg)
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Fructose

  • in fruit
  • slimming foods- sweeter than glucose
  • hexose
    Image result for fructose
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Galactose

  • not as soluble
  • important role in production of glycolipids and glycoproteins
    Image result for fructose (http://media.lanecc.edu/users/rathaketten/FN225/225Lectures/04A/thumbnails/2galactoseThm.jpg)
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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 

Image result for condensation reaction to make maltose

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Hydrolysis Reaction

Image result for hydrolysis of maltose

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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
    Image result for amylose
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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 
    Image result for amylopectinImage result for amylopectin (http://i30.photobucket.com/albums/c349/wee-mama-xyz/graphs/Amylopectin1.jpg)
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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
    Image result for glycogen
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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 
    Image result for triglycerides (http://themedcircle.com/wp-content/uploads/2013/07/triglycerides.jpg)
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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
    Image result for glycerol
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Saturated Fatty Acids

  • RCOOH
  • all carbons bonded to hydrogen 
  • -COOH group is the ester 
    Image result for saturated fatty acid (http://study.com/cimages/multimages/16/saturatedfattyacidpicture2.png)
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Unsaturated Fatty Acid

  • made by plants, oils at room temp
  • kink from double bond
  • possible to join more hydrogens
    Image result for unsaturated fatty acid
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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
    Image result for phospholipid (http://homepage.smc.edu/wissmann_paul/anatomy2textbook/phospholipid.jpg)
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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

Image result for amino acid structure (http://www.nutrientsreview.com/wp-content/uploads/2014/10/Amino-Acid-Structure.jpg)

  • 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
    Image result for amino acid structure (http://www.biology-pages.info/P/Peptide.gif)
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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
    Image result for secondary structure of protein
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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
    Related image
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Quaternary Structure

  • one or more polypeptide chains
  • haemoglobin 
  • can have other substances integrated
    Image result for haemoglobin quaternary structure (http://swift.cmbi.ru.nl/gv/students/mtom/quaternary_haemoglobin.gif)
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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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