23605949
| Question | Answer |
| Describe the test for sugars | -The Benedicts test tests for glycosidic bonds. -Benedicts reagent added to a sample in boiling water bath -Blue to orange if reducing sugars present -Non-reducing sugars need to be hydrolyzed with HCL then made basic with sodium hydrogen carbonate |
| What's the test for lipids? | -The emulsion test -Add food sample to a test tube with 5cm of ethanol. shake. add 5 cm of water -White milky emulsion forms |
| What's the test for proteins? | -The Biurette test tests for peptide bonds -Add NaOH to make basic then add copper(II) sulfate -Positive test goes purple in proteins |
| What's the structure of starch? | -Amylose is long and helical so is compact -Amylopeptin is highly branced to give lots of ends for enzyme action (inc ROR) -Insoluble so dont affect water potential |
| Give the 4 structure levels of Hemoglobin | -Primary: individual sequence of amino acids -Secondary: how the R group atoms form hydrogen bonds with others (Alpha helux, Beta pleated sheets) -Tertiary: folding into 3D shape from H, Disulfide, ionic bonding -Quaternary: multiple protein molocules bonded, prosthetic groups (Haem) |
| What reaction creates Glycosidic bonds? | Condensation reaction forming water as a waste product |
| Give the 3 disaccharides and what they are made from | Maltose: Glucose + Glucose Lactose: Glucose + Galactose Sucrose: Glucose + Fructose |
| What is Cellulose made from? | -Beta Glucose polymer -Changes orientation 180 degrees each molecule -Forms H bonds with adjacent chains -Microfibrills -> Macrofibrills |
| Whats the test for starch? | Iodine in iodide solution Brown to blue/black |
| What's the difference between starch and glycogen? | Glycogen is more highly branched so is more efficiently hydrolyzed by enzymes |
| What's the structural difference between triglyceride and a phospholipid? | Trygliceride: 1 glycerol 3 fatty acid chains Phospholipid: 1 glycerol, 2 fatty acid chains, 1 phosphate group |
| Give the functional differences between triglycerides and phospholipids | Triglycerides: 3 hydrophobic tails, forms lipid droplets, insoluble In water (non-polar entire molecule) energy store Phospholipid: 2 hydrophobic tails, Hydrophilic (polar) head, forms bilayer, structural properties |
| What's produced when glycerol and 3 fatty acid chains undergo condensation reactions? | 1 triglyceride molecule, 3 water molecules |
| What's the difference between saturated and unsaturated fatty acid chains? | Saturated has only single carbon-carbon bonds and is fully saturated with hydrogen atoms -Unsaturated contains at least one double carbon=carbon bond. not fully saturated with hydrogen |
| What 2 functional groups combine when a peptide bond forms? | -COOH from one amino acid and -NH2 from another |
| Give 2 structural functions of fibrous proteins | -Keratin is a protein found in hair and finger nails -Collagen found in connective tissue |
| Give 4 functions of globular proteins | - Enzymes -Carrier and transport proteins -Hormones -Antibodies |
| What are enzymes? | Biological catalysts which provide an alternative reaction pathway with a lower activation energy making a reaction occur faster |
| What's a competitive inhibitor? | -A molecule which has a similar structure to an enzymes substrate so binds to and blocks the active site of an enzyme preventing catalysis -Increasing substrate concentration will increase ROR |
| What's a non-competitive inhibitor? | -A molecule which binds to an allosteric site on an enzyme causing a conformational change in the structure and the active site making it no longer complementary to the substrate. -Increasing substrate conc wont help |
| What's the difference between DNA and RNA? | DNA: deoxy ribose sugar, 2 strands in a double helix, long, made from A,T,C,G, Information storage RNA: ribose sugar, 1 stranded molecule, shorter, AUCG, information transfer |
| Give the stages in semi-conservative replication | 1. DNA helicase unzips helix 2. free floating DNA nucleotides bind 3. DNA polymerase forms phosphodiester linkages making sugar/phosphate backbone 4. 2 new identical DNA molecules, each contains 1old strand 1 new strand |
| How do the different nucleotide bases bond? | A forms 2 hydrogen bonds with T C forms 3 hydrogen bonds with G |
| What does antiparallel mean and how does it affect DNA polymerase? | -Strands in the double helix run in opposite directions - Enzyme can only start from one of the prime ends. So one of the chains is the 'wrong way round' for enzyme action |
| What's the evidence for semi-conservative replication? | 1. bacteria grown in 2 different nitrogen isotope containing broths N14/ N15 2. DNA of different bacteria combines with the Nitrogen isotopes for DNA replication and binary fission 3. Placing bacteria from n14 broth in n15 broth for 1 replication cycle. 4. centrifuging would show DNA settle half way between that of the heavy and light broth DNA and |
| What is the name of this molecule? | Alpha glucose |
| What is the name for this molecule? | Fructose |
| What is the name of this disaccharide? | Maltose |
| What is the name of this disaccharide? | Sucrose |
| What is the name of this molecule? | Galactose |
| What is the name for this disaccharide? | Lactose |
| What is the name for this molecule? | Beta glucose |
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