Biology F212 - Biological molecules 1

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as level Chemistry Flashcards on Biology F212 - Biological molecules 1, created by scarlettcain97 on 05/30/2014.

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scarlettcain97
Created by scarlettcain97 about 5 years ago
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Question Answer
Structure of an amino acid averillfwk-fig24_x052.jpg (image/jpg)
Primary Structure The sequence of amino acids in a protein molecule
Secondary structure Coiling or folding of the chain due to formation of hydrogen bonds. Alpha-helix and Beta-pleated sheet
Tertiary Structure Overall 3D structure of the molecule. Formation of hydrogen bonds, disulphide bridges and hydrophobic & hydrophillic interactions
Quarternary structure Protein structure where it consists of more than 1 polypeptide chain. E.g Haemoglobin has 4 polypeptide chains
Structure of a collagen molecule - 3 polypeptide chains ( 3 syllables=3 chains) - 1000 amino acids long - Hydrogen and covalent bonds form - Cross links are staggered for strength
Structure of haemoglobin - Globular protein -Soluble in water -Wide range of amino acids -Contains 4 haem groups with Fe+ ions -Alpha helix
Structural difference between alpha and beta glucose In alpha glucose the OH group on carbon 1 is above the plane of the ring. In beta glucose the OH group on carbon 1 is below the plane of the ring.
Structure of starch (amylase) -Made of alpha glucose - Straight chain - tends to coil up
Structure of cellulose -Made of beta glucose, in a chain alternate glucose subunits are inverted -Forms straight chains -Forms plant cell walls - The beta-glycosidic bonds can only be broken by a cellulose enzyme (humans don't have this)
Structure of glycogen - Mostly like amylase - many 1-4 glycosidic bonds - 9% 1-6 branches
Structure of a triglyceride - Glycerol and 3 fatty acids -Insoluble in water does not affect cell water potential -Compact energy store
Structure of a phospholipid -Glycerol plus 2 fatty acids and a phosphate group -Part hydrophobic, part hydrophillic (ideal for cell surface membranes)
Cholesterol -Small, thin molecule -Fit into the lipid bilayer giving strength and stability
Chemical test for protein - Biuret test If a protein is present the solution changes colour from pale blue to lilac
Chemical test for reducing sugars -Benedict's test Add benedict's solution, heat to 80 degrees, if a reducing sugar is present the mixture will change colour from blue to orange/red
Chemical test for non-reducing sugars -benedict's test If the reducing test is negative, boil with hydrochloric acid, cool and neutralise with sodium hydrogencarbonate and repeat benedict's test
Chemical test for starch -Iodine solution Colour changes from yellow to blue/black if starch is present
Chemical tests for lipids -emulsion test Mix with ethanol, pour into water, if an emulsion forms then a lipid is present
How the concentration of glucose can be determined by colorimetry -Benedict's test reveals reducing sugars (if there is an orange/brown precipitate) -The more reducing sugar present the more precipitate will form and the more benedicts solution used up. -Once precipitate has been filtered out, the concentration of remaining solution can be measured -This tells you how much benedicts was used up and can be used to estimate the the concentration of reducing sugar in original sample
Preparing a calibration curve - Zero the device using a blank (water) - Take a range of known concentrations of reducing sugars -carry out benedicts test on each and filter out precipitate -Use a colorimeter to get readings of the amount light passing through the solutions -Plot the readings on a graph to show %transmission against concentration -Measure the %transmission of the unknown in the colorimeter -Use this to read the equivalent reducing sugar concentration from %transmission
Deoxyribonucleic acid (DNA) -Is a polynucleotide -Usually double stranded -Made up of nucleotides containing the bases Adenine (A), Thymine (T), Guanine (G), Cytosine (C)
Ribonucleic acid (RNA) -Is a polynucleotide -Usually single stranded - Made up of nucelotides containing the bases Adenine (A), Uracil (U), Cytosine (C), Guanine (G)
DNA replication -Double helix is untwisted - DNA 'unzipped' and hydrogen bonds between bases are broken -Free DNA nucleotides are H-bonded onto their exposed complementary bases -DNA polymerase catalyses formation of covalent bonds between phosphates and sugars -This continues till there are 2 identical strands -These are then 'proof read' by DNA polymerase to prevent mistakes
Gene A gene is a sequence of DNA nucelotides that code for a polypeptide
Protein Synthesis -Required gene exposed by splitting H-bonds holding the helix together in the region - RNA nucleotides form a complementary strand (mRNA) which is a copy of the coding strand -mRNA peels off DNA and leaves via nuclear pores -mRNA attaches to a ribosome -tRNA molecules bring amino acids to the ribosome in the correct order according to base sequence on the mRNA -Amino acids are joined together by peptide bonds to form a protein with a specific tertiary structure
Enzymes -Globular Proteins -Specific tertiary structure -Catalyse metabolic reactions in living organisms -Can be intracellular or extracellular
Enzyme specificity The active site is a specific shape depending on the reaction it catalyses, meaning that other molecules wont fit the active site.
Lock and Key hypothesis The theory of enzyme action in which the enzyme active site is complementary to the substrate molecule
Induced fit hypothesis The theory of enzyme action in which the enzyme active site changes shape to fit the substrate molecule more closely as it binds.