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169 Cards in this Set
- Front
- Back
Enzymes do not affect the equilibrium of a reaction and thus can be bidirectional. True or False |
True |
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List in order the 4 most abundant elements in the body. |
H > O > C > N |
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Name the 3 forms of energy in biology |
Energy carriers. Macromolecules. Electrochemical Gradients |
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Name the most abundant energy carrier |
ATP |
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Name 3 energy carriers which release high energy electrons and H+ |
NADH, FADH, NADPH |
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Oxidation of organic molecules is important for energy production. True or False? |
True. Reduced compounds provide electrons. |
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The loss of a C-H bond in an organic molecule is indicative of which process? |
Oxidation |
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State the concept which describes different metabolic processes occurring in separate parts of the cell or organism |
Compartmentation |
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What is ultimately produced in the pentose phosphate pathway? |
2 NADPH during the pathway. Ribose-5-phosphate -> Nucleotides, coenzymes, DNA, RNA |
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How are lipids processed differently to carbohydrates and protein in the GI tract? |
Need to be emulsified and incorporated into micelles to increase enzyme access |
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Dietary lipids are hydrolysed by which enzymes? |
intestinal/pancreatic lipases |
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Name the amphipathic molecules made from cholesterol which aid emulsification and hydrolysis of dietary lipids |
Bile salts |
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Describe the basic degradation steps of dietary triacylglycerols |
TGs -> DGs + FAs -> MGs + FAs |
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What are the final products of metabolised triglycrides in the intestine? |
One monoacylglycerol and two fatty acids |
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Triacylglycerols combine with proteins and other lipids in mucosal cells to form what? What are the surface proteins called? |
Lipoproteins. Apolipoproteins |
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What are lipoproteins |
Combinations of apolipoproteins and lipids: Chylomicrons, VLDL, IDL, LDL, HDL |
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Name the 4 types of lipoproteins because BIOL214 doesn't admit that IDL exists |
Chylomicrons, VLDL, LDL, HDL and also IDL |
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Describe the function of apolipoproteins |
solubilise lipids, cell targeting, receptor activation |
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Which lipoprotein enters the arterial wall and leads to atherosclerosis? |
LDL |
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Which lipoprotein removes excess cholesterol? |
HDL |
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Name the process by which LDL is taken up by LDL receptors in the liver |
LDL receptor mediated endocytosis |
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Name the drugs used to reduce circulating LDL by inhibiting HMG-COA reductase |
Statins |
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Name the two types of adipose tissue in humans and give their key functions |
White - storage of TGs for ATP production Brown - storage of TGs for thermogenesis |
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Do TGs or CHO have higher energy content per unit mass? |
TGs |
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What are TGs composed of? |
Glycerol backbone, fatty acids |
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In adipocytes, TGs are converted to fatty acids and glycerol through which enzyme? |
Hormone Sensitive Lipase |
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Describe the enzyme pathway downstream of hormone receptor activation TG mobilisation from adipocytes |
Hormone receptor -> adenylyl cyclase -> cAMP -> Protein Kinase A -> lipase |
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The glycerol derived from TGs may undergo metabolism via which pathways? The fatty acids enter which pathway? |
Glycolysis and gluconeogenesis Beta oxidation |
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Beta oxidation occurs at which carbon of the fatty acid chain? |
Beta carbon C-3, carboxyl end |
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In animals, beta oxidation occurs predominantly in which organelle? |
Mitochondria |
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Which enzyme links fatty acids to coenzyme A to form fatty acyl-CoA |
Fatty acyl-CoA synthase |
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Fatty acids longer than 14 carbons enter the mitochondria via what process? |
Carnitine shuttle |
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Beta oxidation is a repetitive 4 step process by which fatty acids are converted to what? |
Acetyl-CoA, FADH2, NADH Notice these are all involved in krebs |
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What are the 4 repetitive steps of beta oxidation? |
Oxidation Hydration Oxidation Thiolysis |
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What is the key intermediate molecule between lipid and carbohydrate metabolism? |
Acetyl-CoA |
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Beta oxidation of unsaturated fatty acids requires additional steps involving what two enzymes? |
Isomerase and reductase |
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Complete Beta oxidation of odd-chain fatty acids requires additional steps. What is the final product arising from these steps and the essential vitamin required? |
Succinyl-CoA Vitamin B12 |
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Vitamin B12 deficiency prevents metabolism of fatty acids and results in what disorder? |
Odd chain fatty acids -> spinal cord degeneration |
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How do inborn errors to medium chain acyl-CoA dehydrogenase impair lipid metabolism? |
Inability to oxidise 6-12 carbin fatty acids |
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What step in Beta oxidation does acyl-CoA dehydrogenase catalyse? |
First. Oxidation. |
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Fatty acid metabolism of gut bacteria is important to human health. T or F |
True |
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Acetyl-CoA is moved from mitochondria to cytoplasm via what transporter? |
Citrate transporter
|
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Which enzyme converts acetyl-CoA to malonyl-CoA to begin fatty acid synthesis? |
Acetyl-CoA carboxylase |
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Which multi enzyme complex catalyses fatty acid synthesis? |
Fatty acid synthase |
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List the four repetitive steps of fatty acid synthesis |
Condensation Reduction Dehydration Reduction |
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Fatty acid synthesis terminates at which end product? |
Palmitate 16:0 |
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Mammals lack the ability to introduce double bonds beyond which carbon position in fatty acids? |
After carbon 9, so carbon 10 onwards |
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Which enzyme introduces double bonds into fatty acids? |
Fatty acyl-CoA desaturase |
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Which enzyme is the key control point of fatty acid metabolism? |
Acetyl-CoA carboxylase? |
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True or False: Triacylglycerol and glycerophospholipid synthesis share a common start point? |
True |
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What is the starting point for triacylglycerol and glycerophospholipid synthesis? |
Phosphatidate |
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What precursor molecules give rise to phosphatidate? |
Glycerol-3-phosphate and fatty acyl-CoA |
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Fatty acyl-CoA and acyl-CoA synthase are involved in phosphatidate synthesis. What else are these compounds involved in, in lipid metabolism? |
Fatty acid degradation/Beta oxidation (carnitine shuttle) |
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Which sphingolipid is the starting point for the synthesis of other sphingolipids? |
Ceramide |
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Which two key substrates are required for the synthesis of sphingosine? |
Palmitoyl-CoA Serine |
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Sphingosine and fatty acyl-CoA form what? |
Ceramide |
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Ketone body formation occurs mainly in which organ? |
Liver |
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Name the end product of Beta oxidation which also serves as the starting point for ketone body synthesis? |
Acetyl-CoA |
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In lipid metabolism, acetone, acetoacetate and D-B-hydroxybutyrate are types of what? |
Ketone bodies |
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Ketone body production occurs mainly in the liver due to high levels of which enzyme? |
HMG-CoA synthase |
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What two health conditions are often associated with increased ketone body formation? |
Starvation (also ketosis) Diabetes |
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Why does ketone body formation increase in starvation and diabetes? |
Increased gluconeogenesis depletes TCA cycle intermediates to prevent FA-derived acetyl-coa from TCA cycle entry |
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Eicosanoids are derived from what membrane phospholipid-derived fatty acid? |
Arachidonate |
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Arachidonate is derived from what type of fatty acids? |
Essential omega fatty acids |
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What enzyme causes the release of arachidonate from membrane phospholipid? |
Phospholipase A2 |
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List the 3 major classes of eicosanoids |
Prostaglandins Thromboxanes Leukotrienes |
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What enzyme converts arachidonate into prostaglandins and thromboxanes? |
Cyclooxygenase (prostaglandin H2 synthase) |
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What enzyme group converts arachidonate to leukotrienes? |
Lipooxygenases |
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What group of common household drugs prevent prostaglandin and thromboxane synthesis? |
Non Steroidal Anti Inflammatory Drugs |
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Cholesterol is synthesised from what basic precursor molecule? |
Acetyl-coa |
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List the basic steps of cholesterol synthesis |
Acetate -> mevalonate -> activated isoprene -> squalene -> lanolesterol -> cholesterol |
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Cholesterol lowering compounds, statins, target which enzyme? |
HMG-coa reductase |
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Cholesterol is more commonly transported in blood as? |
Cholesteryl esters |
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Bile salts and steroid hormones are derived from which lipid? |
Cholesterol |
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What steroid hormone is an intermediate of other steroid hormones? |
Pregnenolone |
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List water and lipid soluble vitamins: |
Water: B C Lipid: A D E K |
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Energy carriers are derived from what vitamins? |
Vitamin B family FADH = B2 NAD(P)H = B3 CoA = B5 |
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What vitamin is derived from cholesterol? |
Vitamin D |
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What vitamins are derived from activated isoprene? |
Vitamins A E K |
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Vitamin D3 is derived from cholesterol but needs additional steps to become biologically active. True or False? |
True. UV light to skin -> liver -> kidney |
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Name the biologically active form of vitamin D |
1a,25-Dihydroxyvitamin D |
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Vitamin D deficiency results in what to health conditions? |
Rickets Osteomalacia |
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Name the process which converts solar energy to biochemical energy |
Photosynthesis |
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Write the basic equation for photosynthesis |
2H2O + photons + CO2 -> (CH2O)n + O2 Water + photons + carbon dioxide -> Carbohydrates + oxygen |
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Name the 2 main reactions of photosynthesis |
Light Dark (carbon assimilation) |
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Name the 3 main products of light reactions |
ATP, NADPH and O2 |
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Name the organelles which capture light and convert it to chemical energy |
Chloroplasts |
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Name the structure where light reactions take place |
Thylakoid membrane |
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Name the structure where dark reactions take place |
Stroma |
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What is the main photorecptor in chloroplasts? |
Chlorophyll |
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Chlorophyll mainly absorbs what 2 regions of visible light? |
Blue and Red regions i.e. leaving green to be reflected |
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Secondary light absorbing pigments are also known as what? |
Carotenoids (Beta-carotene and lutein) |
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Why are secondary light absorbing pigments important? |
Expand the range of wavelengths absorbed |
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Name the arrays containing arranged light-absorbing pigments |
Photosystems |
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Outline the basic organisation of photosystems |
Chlorophylls and other pigments surround the reaction centre. Chlorophylls and pigments with proteins form LHCs |
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A nucleotide is made up of a...? |
Phosphate - Pentose - Purine/Pyrimidine base |
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Name the two pathways by which purine bases can be assembled |
De novo purine synthesis purine salvage pathway |
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Complete the following sentence. _____ is an important branch point in purine biosynthesis. |
IMP (Inosinate monophosphate) |
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Name the amino acids required to form AMP and GMP from IMP. |
AMP - Aspartate - Enzyme: Adenylosuccinate synthetase GMP - Glutamine - Enzyme: IMP dehydrogenase |
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The first committed step in purine biosynthesis involves which enzyme? |
Glutamine-PRPP amidotransferase |
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The enzyme responsible for the breakdown of hypoxanthine -> xanthine -> uric acid is what? |
Xanthine oxidase |
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What medication, an isomer of hypoxanthine, inhibits xanthine oxidase and is a treatment for gout? |
Allopurinol |
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Gout is caused by an accumulation of what? |
Sodium Urate deposits in the joints |
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The enzymes that remove ammonium ions NH4+ during purine nucleotide catabolism (salvage pathway) are known as what? |
Deaminases |
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What is the main source of amino acids? (Food) |
Dietary proteins |
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What are zymogens? |
Proenzymes which need to be cleaved to be activated such as trypsinogen or pepsinogen. |
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Which amino acid is transported to the liver from working muscle? |
Alanine (amino side chain, like glutamine) |
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Which amino acid is transported to the liver from extrahepatic tissues (not working muscle)? |
Glutamine (amino side chain makes it a viable transporter) |
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How do these excrete nitrogenous wastes: Bony fish Birds Terrestrial animals and sharks |
Fish - ammonia Bird - uric acid Human - urea |
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The enzyme which catalyses the first step in the urea cycle is ___________ |
The enzyme which catalyses the first step in the urea cycle is carbamoyl phosphate synthase I |
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Hyperammonemia is what? Besides a waste of a flash card |
Excessive ammonia in the blood |
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Can most amino acids directly enter the TCA cycle? |
Most AAs cannot enter the TCA cycle directly and must be converted to other AAs. E.g. Phe -> Tyr via phenylalanine hydroxylase |
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Which enzyme is defective in phenylketonuria and what effect does this have? |
Phenylalanine hydroxylase. fails to convert phe to tyr, buildup of phe -> retardation |
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What is the main storage site of amino acids in our body? |
Muscle |
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What is the key problem of starvation diets? |
Glycogen depletion and shift to muscle catabolism for AAs/gluconeogenesis |
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4 problems with 'high protein' (ketogenic not high protein really junk question) are: |
Risks of ketogenic diets: Hypoglycemia Ketoacidosis Hyperlipidemia Hyperammonia *suspicious question |
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The process by which bacteria and archaea convert N2 to NH3 is ________ |
The process by which bacteria and archaea convert N2 to NH3 is nitrogen fixation Step 1: Fixation |
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The four chemical transformations that maintain a balance between N2 and biologically useful nitrogen are... |
1. Fixation. N2 -> NH3 2. Nitrification. NH3 -> NO2- 3. Assimilation. NO2- -> NH3 4. Denitrification. NO3- -> N2 |
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The key role of glutamate in biosynthesis is _____ and _______ |
A key entry point for nitrogen into biomolecules. Along with glutamine it is one of the 2 major sources of N for biosynthesis reactions. |
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Glutamine synthetase converts _______ into glutamine through ________ of _________ and then replacement of __ with ____. |
Glutamine synthetase converts glutamate into glutamine through phosphorylation of carboxylic acid side chain and then replacement of Pi with NH3. |
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Is glutamine synthetase a major regulatory point in biosynthesis? |
Yes it is a key control point |
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Two mechanisms by which glutamine synthetase is regulated are: |
Adenylation (stimulated by glutamine and Pi) Allosteric inhibition by products such as a-ketoglutarate. |
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Name the three pathways which yield carbon skeletons for AA synthesis. |
Glycolysis Krebs Pentose Phosphate Pathway |
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Essential amino acids must be supplied by diet T/F |
True |
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Name the reactions used to transfer an amine group, usually from glu or gln, to a carbon skeleton for amino acid synthesis |
Transamination reactions catalysed by aminotransferases |
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In addition to biosynthesis, amino acids are involved in energy production. List 3 main energy pathways they are involved in. |
Gluconeogenesis TCA cycle Ketogenesis |
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Name the enzyme which converts arginine to nitric oxide |
Nitric oxide synthase |
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Which enzyme makes PRPP from ribose-5-phosphate? |
PRPP synthetase |
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Which enzyme uses glutamine to add nitrogen to PRPP? |
Glutamine-PRPP amidotransferase |
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Cytidylate is an example of nucleoside, nucleotide or nucleic acid? |
Nucleotide Phosphate - Ribose - Cytosine |
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The carbon and nitrogen atoms in the pyrimidine ring come from which two molecules? |
Carbamoyl phosphate and Aspartate |
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Where is carbamoyl phosphate 1 located, what process does it make carbamoyl phosphate for? |
Hepatic mitochondria, urea cycle |
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Where is carbamoyl phosphate 2 located, what process does it make carbamoyl phosphate for? |
Cytosol. Pyrimidine de novo synthesis |
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Why are dTTP synthesis enzymes valid targets for chemotherapeutic agents? |
Inhibit DNA synthesis as dTTP is unique to DNA and needed for its synthesis. Example drug: 5-fluorouracil -> 5-fluorodeoxyuridylate (5-dUMP) irreversibly inhibits enzyme that produces dTMP. |
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Name two the photosystems in chloroplasts |
PS II and PS I |
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Name the complex which links PS II to PS I |
Cytochrome B6F |
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Give the main function of Cb6f |
Pump protons into the thylakoid lumen |
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Increased protons in the thylakoid membrane lead to the generation of what? |
ATP via ATP synthase |
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Name the protein that carries electrons from C b6f to PS I |
Plastocyanin |
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Distinguish between non cyclic and cyclic electron transfer from ferredoxin |
Non cyclic drives NADPH production Cyclic drives proton gradient and subsequent ATP production |
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Which two products of light reactions feed directly into the calvin cycle? |
NADPH and ATP |
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What are the 3 stages of the calvin cycle? |
1. CO2 -> 3-phosphoglycerate 2. 3-phosphoglycerate -> Glyceraldehyde-3-phosphate 3. Triose phosphate -> ribulose-1,5-bisphosphate |
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What enzyme catalyses the first step in the calvin cycle? What is its limitation? |
Rubisco aka ribulose-1,5-bisphosphate carboxylase oxygenase It has very low activity |
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How many of the triose phosphates generated in the calvin cycle must be recycled to ribulose-1,5-bisphosphate? |
80% |
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Besides low activity what is another limitation of rubisco? |
Fixes O2 as well as CO2 |
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What waste product can rubisco form? |
2-phosphoglycerate |
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Name 3 organelles involved in salvage of 2-phosphoglycerate |
Mitochondrion, peroxisome, chloroplast |
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What is the first step in c4 carbon assimilation |
CO2 -> HCO3- -> Oxaloacetate |
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Name the enzyme which catalyses the first step of C4 carbon assimilation |
Phosphoenolpyruvate carboxylase |
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What two cell types are required for C4 pathway in plant leaves? |
Mesophyll and bundle-sheath cells |
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Chemical energy in the form of ATP and NADH is used in what kind of reaction in the body? |
Endergonic, unfavourable reactions |
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Define enthalpy |
Total potential energy of a system |
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Define entropy |
a measure of increasing disorder due to energy lost during transformations |
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How do enzymes lower the activation energy of reactions? |
Orientation of reactants at active site |
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Oxidation is ____ of electrons, reduction is ____ |
Oxidation is loss of E- Reduction is gain of E- |
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What is the primary antioxidant in animals and which enzyme replenishes it when oxidised? |
Glutathione Glutathione reductase and also NADPH |
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Humans may lose consciousness below what blood glucose concentration? |
3.5mmol/L |
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Which organ is primary storage reserve of glucose? |
Liver as glycogen |
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What energy sources are used by brain? |
Glucose, Ketone bodies |
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Which organ is able to use phosphocreatine as an energy source? |
Muscle |
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What is the effect of insulin on blood glucose? |
Insulin decreases blood glucose and begins storage processes |
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What is the effect of glucagon on blood glucose? |
It increases blood glucose by lipolysis, gluconeogenesis |
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What are the effects of ghrelin and leptin on appetite? |
Ghrelin = hunger, remember GH increased growth hormone when fasting Leptin = satiety, released when full. Obese may be leptin resistant |
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List 4 metabolic effects of cortisol. What is one health condition that can arise from prolonged cortisol release and why? |
Increased lipolysis Increased gluconeogenesis Muscle catabolism Increased glycogenolysis. Type 2 diabetes, long term increase in blood glucose and insulin resistance. |
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What are the two main cellular locations of receptors? |
Membrane and Intracellular: cytosol/nucleus |
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What are the 3 main types of receptors important in metabolism? |
Growth factor receptors e.g. insulin G-protein coupled receptors e.g. glucagon epinephrine Steroid receptors e.g. glucocorticoids, sex hormones |
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How is the insulin signal controlled? |
Binds to receptor to form dimer, activating tyrosine kinase, kinase cascade occurs, activating response proteins and enzymes. Receptor signal is controlled by internalisation of insulin receptor - endocytosis. |
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What are the function of STATs in leptin signalling? |
STATs enter the nucleus in hypothalamic cells and regulate transcription |
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Name one enzyme activated by the second messenger cAMP |
cAMP activates Protein Kinase A |