Biological Molecules

  • Created by: JosephPHS
  • Created on: 27-01-23 10:20
Condensation reaction
H2O Removed
Glycosidic bond formed
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H2O Added
Glycosidic bond broken
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Difference between α and β glucose
H and OH on C1 inverted
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α glucose + α glucose
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α glucose + fructose
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α glucose + galactose
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Test for Reducing Sugars
Add excess Benedict's Reagent
Heat in water bath
Blue --> Brick Red
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Test For Non-Reducing Sugars
Add dilute HCl
Heat in Water Bath
Neutralise with NaHCO3 (Sodium Hydrogen Carbonate)
Add excess Benedict's Reagent
Heat in water bath
Blue --> Brick Red
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α Glucose store in plants
Insoluble in water - doesn't affect water potential - doesn't cause water to enter cells by osmosis (good for storage)
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Test for starch
Iodine test

Add iodine in KI solution
Brown/Orange --> Blue/Black
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Unbranched chain of α glucose
Coiled structure - Compact - Good for Storage
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Highly branched chain of α glucose
Side branches - Sites for hydrolysis by enzymes - Quick release of glucose
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α Glucose store in animals
Similar structure to amylopectin but more branched - Quick release of energy
Compact - Good storage
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Used in cell walls of plants
Long, unbranched chain of β glucose
H bonds form strong microfibril fibres
Strength gives cellulose structural uses
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Used as energy storage molecules
Glycerol + 3 Fatty acid 'tails'
Tails are hydrophobic - insoluble in water - Don't affect water pot of cells and don't cause water to enter cell by osmosis
Long hydrocarbon tails contain lots of energy
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Formation of Triglycerides
Glycerol + 3 Fatty acids
Condensation reaction
Ester bond between glycerol and each tail
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Saturated vs Unsaturated
Saturated - No double bonds, 'Saturated' with H
Unsaturated - At least one double bond between C, causes a 'kink' in the chain
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Used to make cell membrane bilayer
Phosphate + Glycerol + 2 Fatty acids
Hydrophilic phosphate heads
Hydrophobic fatty acid tails
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Test for Lipids
Emulsion test

Submerge sample in ethanol so it dissolves
Pour into water
Milky colour
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Made up of amino acids
Made of one or more polypeptides
General structure with differing variable (R) group
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Protein Structure
H2N - C - COOH

NH2 - Amine group, COOH - Carboxyl Group,
R - Variable Group
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2 Amino Acids bonded
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>2 Amino Acids bonded
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Formation of Polypeptides
Condensation reaction forms peptide bond between two amino acids
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Primary Structure
Amino Acid sequence
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Secondary Structure
H bonds lead to coiling forming an α helix or folding forming a β pleated sheet
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Tertiary Structure
Further folding/coiling from more H bonds, ionic bonding and disulfide bridges form a 3D structure
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Quaternary structure
Combination of multiple polypeptide chains
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Functions of Proteins
Enzymes, Antibodies, Transport proteins (cell membrane), Structural proteins (collagen, keratin)
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Test for Proteins
Add a few drops of NaOH - forms basic solution
Add Cu(ii) SO4
Blue --> Purple
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Speed up chemical reactions
(Biological catalysts - not used up)
Reduce activation energy of metabolic reactions
Made up of protiens
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Lock and Key model
Enzyme active site is exactly complimentary to shape of substrate(s)
Substrate(s) fit in to enzyme like a key to a lock
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Induced fit model
Enzyme active site is somewhat complimentary to shape of substrate(s)
As substrate(s) approaches active site changes shape slightly to form enzyme-substrate complex
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Protein structure of enzymes
Tertiary structure of an enzyme provides it with active site specific to its substrate(s)
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What can alter active site of an enzyme
Temperature, pH, or non-competitive inhibitor

*Mutation in gene that gives primary structure of enzyme can also alter tertiary structure as different bonds will be formed
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Effect of temperature
High temperatures causes more kinetic energy so rate of reaction is increased until optimum
Post-optimum H bonds and disulfide bridges begin to break and shape of active site is changed
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Effect of pH
Enzymes have optimum pH generally related to where they carry out their function. Outside of optimum H+ and OH- ions break ionic and H bonds in tertiary structure changing active site shape
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Effect of Enzyme Conc.
As more enzymes are present rate of reaction increases as more active sites are available for reaction so more chance of collision. Steady increase in RoR until substrate conc. becomes limiting factor
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Effect of Substrate Conc.
As more substrate is present RoR increases as higher chance of collision. Steady increase of RoR until all active sites are used up
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Competitive inhibitors
Bind directly to the active site preventing substrate(s) from binding so RoR is lowered.
If substrate conc. is increased RoR will eventually catch up as there is many more substrate(s) than inhibitors
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Non-Competitive inhibitors
Bind to the allosteric site of the enzyme and change the shape of the active size. If substrate conc. is increase RoR will increase but is capped as enzymes will not return to original state
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Deoxyribonucleic Acid
Polymer of nucleotide monomers with double helix structure
Determines 3D structure and function of protein
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Pentose Sugar
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Polymer formed of nucleotides

Condensation reactions form phosphodiester bond between deoxyribose and phosphate group. Creating sugar phosphate backbone. Hydrogen bonds form between bases, forming double helix
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Single stranded polymer of phosphate, ribose sugar and nitrogenous base
Thymine replaced by Uracil

Function - Transfers genetic code from DNA to ribosomes
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Name of DNA replication
Semi-Conservative Replication
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Semi-Conservative Replication
DNA unzipped into 2 single strands with each forming a new separate strand of DNA so that each new strand contains 50% parent DNA and 50% new DNA
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DNA Replication
DNA helicase breaks hydrogen bonds (unzips DNA)
Parental DNA acts as template for free nucleotides to bond
DNA polymerase catalyses condensation reaction to form phosphodiester bonds between nucleotides
2 Sets of daughter DNA formed
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Evidence for Semi-Conservative DNA replication
Meselson and Stahl's experiment of heavy and light nitrogen based DNA
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Adenosine Triphosphate

Adenine, Ribose sugar and 3 phosphate

Store of energy for metabolic reactions
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Properties of water
Acts as a metabolite (condensation/hydrolysis)
Solvent of reactions
High specific heat capacity
Large latent heat of vaporisation cooling effect when evaporated
Cohesive forces support water columns an surface tension
Less dense as solid than liquid provi
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Uses of H ions
Lower pH of solutions, affects enzyme activity and haemoglobin function

Proton pump in chemiosmosis
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Use of Fe ions
Form haem group for transport of oxygen
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Use of Na ions
Co-transport of glucose and amino acids in absorption

Generation of action potential (depolarisation)
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Uses of phosphate ions
Component of DNA in formation of phosphodiester bonds and part of deoxyribose sugar

Phosphate groups of ATP
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Other cards in this set

Card 2


H2O Added
Glycosidic bond broken



Card 3


H and OH on C1 inverted


Preview of the back of card 3

Card 4


α glucose + α glucose


Preview of the back of card 4

Card 5


α glucose + fructose


Preview of the back of card 5
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