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89 Cards in this Set
- Front
- Back
what is a protein?
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polymer of amino acids
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what is a carbohydrate?
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monomer, dimer, oligomer or polymer of sugars
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what is a fat?
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ester of carboxylic acids
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how many common amino acids are there?
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20
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what links amino acids to form peptides, polypeptides and proteins?
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peptide bonds
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Which enzyme is deficient in PKU?
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phenylalanine hydroxylase
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what does phsnylalanine hydroxylase do?
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converts phenylalanine to tyrosine
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what is starch composed of?
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amylose (25%) and amylopectin (75%)
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which disaccharide is composed of two glucose molecules?
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maltose
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where is glycogen stored?
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hepatocytes
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what are the two components of a triglyceride?
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glycerol molecule, fatty acids
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what is the primary site of nutrient digestion and absorption?
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small intestine
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What is ATP?
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adenosine 5-triphosphate... a mobile source of energy for cells
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what is the action of water on ATP?
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cleaves the terminal phosphate leaving ADP and phosphate (releases energy)
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what is the turnover rate of ATP?
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40 kg per day
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What is NAD+?
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nicotinamide adenine dinucleotide (oxidised), reduced form is NADH
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what is coenzyme A?
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a carrier for fatty acids
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What are the key outcomes of the citric acid cycle?
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nutrient substrates are fed into the cycle as 2C units (Acetyl CoA), electrons are stripped from nutrient substrates and are transferred to NAD+ and FAD to generate NADH and FADH2 and CO2 is generated
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what is the major pathway for extraction of energy from carbohydrates?
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glycolysis (conversion of glucose to pyruvate or lactate)
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true or false... glycolysis can handle glucose and galactose but not fructose
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false, it can handle all three
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how many molecules of ATP are generated in the glycolytic pathway?
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2 per glucose molecule
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where does glycolysis occur?
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in the cytoplasm
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What are the requirements for the conversion of pyruvate to acetyl CoA (and entry to the Citric Acid Cycle)?
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source of NAD+, source of CoA (CO2 generated), entry from cytoplasm into mitochondrial matrix
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which enzyme converts pyruvate to acetyl CoA?
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pyruvate dehydrogenase
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what are the conditions for the mitochondrial metabolism of pyruvate?
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adequate levels of oxygen, adequate levels of NAD+ and adequate levels of thiamine
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Without adequate levels of oxygen, NAD+ and thiamine, what will pyruvate be converted to?
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lactate
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List some causes of lactic acidosis
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hypoxaemia, thiamine deficiency, pyruvate dehydrogenase deficiency, drugs (biguanides, alcohol)
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t/f... in lactic acidosis, ATP synthesis exceeds ATP breakdown
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false, the opposite is true
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t/f... protons are released as a result of net ATP breakdown
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true
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what are the clinical features of lactic acidosis?
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low pH, high serum lactate levels, elevated resp rate, muscle achea
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What is the pathway for the conversion of fatty acids to Acetyl CoA?
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fatty acid oxidation
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t/f... the reactions involved in fatty acid oxidation occur at the alpha carbon?
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false, they occur at the beta carbon
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how does alcohol dependence lead to thiamine deficiency?
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alcohol displaces other nutrients, interferes with thiamine absorption, may accelerate thiamine turnover
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what is another name for ubiquinone?
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coenzyme Q
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where is coenzyme Q synthesised?
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mitochondrial matrix
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what tethers ubiquinone to the inner mitochondrial membrane?
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the hydrophobic isoprenoid side chain
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what is the fully reduced form of ubiquinone?
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ubiquinol (QH2)
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how many amino acids does cytochrome C have?
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120
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what lies at the centre of a heme molecule?
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an iron binding nucleus
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which protein complex accepts the electrons from NADH?
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Complex I
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What is another name for Complex III?
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cytochrome C reductase
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what is another name for complex IV?
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cytochrome oxidase
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what is the function of Complex I?
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it uses NADH to reduce Q (QH2 forms)
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Which complex uses QH2 to reduce Cytochrome C?
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Complex III (cytochrome C reductase)
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At what stage in the electron transport chain is water generated?
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Complex IV (uses reduced cytochrome C to reduce O2 to H2O)
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Which complex uses FADH2 to reduce Q?
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Complex II
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t/f... complexes I, III and IV (but not II) are electron-driven proton pumps
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true
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What is another name for Complex V?
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ATP synthase
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what is oxidative phosphorylation?
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extraction of electrons from nutrients to drive ATP synthesis
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what happens if oxidative phosphorylation is uncoupled?
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ATP synthesis fails and heat is generated
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what are the similarities between DNA and RNA?
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sugar-phosphate backbone, presence of purine and pyrimidine bases
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what are the differences between DNA and RNA?
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double stranded v single stranded, sugar: 2'-deoxyribose v ribose, bases: AGCT v AGCU
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Name the pyrimidines of RNA.
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cytosine and uracil
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name the pyrimidines of DNA
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cytosine and thymine
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name the purines of DNA/RNA
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adenine, guanine
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what is the function of transfer RNA?
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recruit amino acids for protein synthesis
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which type of RNA is derived from a template strand of genomic DNA?
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messenger RNA
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what modifications are made during processing of mRNA?
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capping (at 5' end), cleavage at 3' end, polyadenylation, splicing, editing
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t/f... RNA does not form double helices but it can base pair
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true
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where does translation occur?
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on ribosomes
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where are ribosomes located?
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cytoplasm, mitochondrial matrix
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where does ribosome assembly occur?
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nucleolus
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What is meant by positive sense RNA?
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single stranded DNA which is recognised as mRNA and immediately translated
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which of these RNA viruses are negative sense? Hep C, retroviruses, SARS,influenza, measles, rabies, rotavirus, mumps
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influenza, measles, mumps, rabies.
(positive sense: SARS, Hep C, retroviruses; double stranded: rotavirus) |
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what is the additional capability of retroviruses?
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ability to synthesise DNA (reverse transcriptase)
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what is the name of the plane in which the 6 atoms of a peptide bond group are located?
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amide plane
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what maintains the position of atoms in the amide plane?
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the peptide bond has a partial double bond character which limits the mobility of surrounding atoms
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where are the two degrees of freedom for each amino acid?
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angle about C(alpha)-N bond (phi) and the angle about C(alpha)-C bond (psi)
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which secondary protein structure is sheet like?
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beta
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what is the alpha secondary structure?
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helix
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in the alpha-helix, how many amino acids complete one turn?
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4
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where are H-bonds located in the alpha helix?
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between the backbone C=O and HN residues along peptide chain
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t/f... the side chains point towards the centre of the alpha helix?
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false, they point outwards from the centre
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where do the side chains point in a beta sheet?
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alternately down and up
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how are sheets and helices joined?
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by loops (antiparallel and parallel structures)
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what is an enzyme?
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biological catalyst that markedly enhances the rate of a chemical reaction
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how does activation energy relate to the speed of a reaction?
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the higher the activation energy, the slower the reaction
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why do catalysed reactions run faster?
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activation energy is lower
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what are the three types of inhibition?
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competitive - inhibitor and substrate compete for enzyme's active site
non-ompetitive - inhibitor binding site and substrate-binding site are distinct un-competitive - inhibitor binding site and substrate-binding site are distinct/inhibitor binds preferentially to the EX complex |
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what is the major configuration in nature of fatty acids?
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cis
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how is carbohydrate stored?
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as glycogen in the liver (and muscle)
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where is protein stored?
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skeletal muscle, liver
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where is fat stored?
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truglycerides in adipose tissue, liver
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what stimulates glycogen synthase activity?
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insulin
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what stimulates glycogen phosphorylase activity?
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glucagon
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where does gluconeogenesis occur?
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liver and kidney
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what are some acute triggers for insulin release?
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elevated plasma glucose level, elevated plasma amino acids, elevated free fatty acid levels, release of gut peptides
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what is the acute trigger for glucagon release?
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low plasma glucose
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what is the site of insulin and glucagon production?
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pancreatic islets
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