MCAT Biology 1- Biochemistry PART 1
MCAT Biology 1- Biochemistry PART 1 CHEM 2223
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This 9 page Test Prep (MCAT, SAT...) was uploaded by ShayD on Wednesday January 13, 2016. The Test Prep (MCAT, SAT...) belongs to CHEM 2223 at University of Missouri - St. Louis taught by John Gutweiler in Fall 2015. Since its upload, it has received 76 views. For similar materials see Quantitative Analysis in Chemistry at University of Missouri - St. Louis.
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Date Created: 01/13/16
MCAT Biology 1 Review: *** This study guide will refresh and enhance your knowledge, however it assumes you have a basic understanding of biology and chemistry*** Amino Acids: α amino group, tetrahedral α carbon, α carboxyl, variable R group Properties: *amphipathicboth hydrophobic/philic (phospholipid bilayer) Hydrophobic (Non Polar): everything else Hydrophilic: o Polar “Threon the Ty rex hates Seared Gluten Crusted Asparagus => Serine, Cysteine, Tyrosine, threonine, Asparagine, Glutamine o Acid has acid in the name o Basic “His argument is Lysed” => Lysine, Arginine, Histidine Structure: Hydrophobic (Non Polar): mostly alkanes R group; rings on proline (cyclobutane ring N as R group), phenylalanine, tryptophan; methionine (thioester S ether) Hydrophilic (polar) Neutral: Contains an oxygen; tyrosine (thiol ring); cysteine has sulfhydryl Hydrophilic (polar) Acidic: carboxylic acid as the R group Hydrophilic (polar) Basic: nitrogen containing R groups NOT tryptophan Thermodynamics: does indicate the direction of reaction DOESN’T indicate rate st 1 law conservation of energy 2 law entropy tends to increase; spontaneous reaction tend to increase the disorder 3ed law ∆ G=∆H−T ∆S C ][D ] Q= A [B] = products/reactants [ ] ∆G= free energy (energy reactantproducts); Q>1= products, Q<1= reactants ∆H= enthalpy ∆S= entropy T=temp. ∆G= negative} spontaneous Exergonic ∆G= + positive} non spontaneous Endergonic ∆G= 0} equilibrium ∆H= negative} exothermic (energy output) ∆H= + positive} endothermic (energy input) Macromolecules: Proteins: o Basic unit: amino acid Bonds: covalent peptide bonds (amino acid chains NC) disulfide bridges (cysteine R groups) Denature via temperature renders proteins as nonfunctional o Structure Primary amino acid sequence peptide bond Secondary initial folding of polypeptide chain: α helix or ẞ pleated hydrogen bonds Tertiary folding with hydrophobic amino acid outside disulfide, van der walls Quandarylarge complexes everything beside covalent (peptide, disulfide) Carbohydrates: o Energy storage Animals Glycogen Plants Starch o Storage=> cellulose (betaglycosides bonds) cannot digest o Glyosidic linkages dehydrating reaction CnH 2n n Don’t forget hydrolysis with macromolecules Maltose glucose+ glucose Sucrose glucose+ fructose Lactose glucose+ galactose o Formula is to subtract H 2 Lipids: o Roles Adipose cells energy cells Cellular membrane phospholipid barrier, intracellular Cholesterol fluidity and hydrophobic steroid hormones o Fatty acid structure: alkanes with carboxylic acid Saturated (single bond) and unsaturated (double bonds “Z or cis”) o Triacylglycerol Three fatty acid Glycerol Bond: ester linkages R o Phospholipids Lipid bilayer Phosphate head (hydrophobic) 2x fatty acids Glycerol Cholesterol o general structure: o Lipoproteins= hormones Estradiol Testosterone Enzymes: Covalent modification: o Adds covalent groups to regulate activity, lifespan, and/or cellular location Addition if phosphoryl via kinase Phosphorylation can either activate or inactivate the enzymes Proteolytic cleavage: o Inactive enzymes (zymogens) can be activated via proteases Association with other polypeptides: can affect enzyme activity Allosteric regulations “on off” mechanism o Regulation not at the active site Feedback regulation: o Positive and negative (amplify or diminish final product depending on the amount of product Enzyme kinetics: Reaction rate (V) is amount of product formed per unit of time, mol/s o V maxwhen enzyme is saturated Adding substrate doesn’t increase rate Michaelis constant (Km) is the substrate concentration at which velocity is half its maximum After a certain [S] many active sites are occupied Inhibition types Competitive o Compete with substrates for binding sites Vmax s not affected adding most [S] can outcompete inhibitor It takes more [S] so increasedmK Noncompetitive o Binds at allosteric site Vmax s affected but m is no changed since max2 Uncompetitive o Only binds to enzymesubstrate Cannot bind to[S] o Decreases amount of available enzymesubstrate decrease V amaxK m Mixedtype o May bind either to unoccupied enzyme or enzymesubstrate complex ∆ Km epends on enzyme affinity to either inhibitor or substrate Vmax ecreases Cellular Respiration Redox Reaction: “oil rig” oxidation is loss; redox is gain (in chemistry this is elections) Oxidation Redox Gains oxygen Losses oxygen Losses hydrogen Gains hydrogen Losses electrons Gains electrons Four stages: o Glucose is split in half – small NADH and ATP glycolysis Location cytosol Oxygen needed NO o Pyruvate is decarboxylated to for acetylcoA small NADH Location outer mitochondria matrix (entering) Oxygen needed yes; indirectly o acetylcoA is transformed to form NADH, FADH , small ATP 2 Location mitochondria matrix Oxygen needed yes; indirectly o ETC reduces electron carriers, oxidizes NADH and FADH ne2ds oxygen Location mitochondria inner membrane Oxygen needed yes directly Glycolysis: 2 ATP and 2 NADH with 2 pyruvate o Old pathway billions of years old Glucose+2ADP+2Pi+2NAD→2 pyruvate+2 ATP+2NADH+2H 2O+2H Hexokinase makes G to G6P (G6P inhibits hexokinase) Phosphoglucose isomerase G F Phosphofructokinase (inhibited by ATP) F 1,6biP Glyceraldehyde Isomerase x2 Gde3P Dehydrogenase x2 1,3biPGate Kinase x2 3PGate Mutase x2 2PGate Enolase x2 PEP Pyruvate Kinase x2 Pyruvate o Phosphofructokinase this step we transfer a phosphate group from ATP, PFK is thermodynamically very favorable (practically irreversible); known as the committed step Pyruvate Dehydrogenase complex (PDC) 2 NADH per glucose o Pyruvate goes through oxidative decarboxylation, which mean CO and NAD2 is produced reducing the pyruvate to a 2 Carbon molecule This process is done for the two pyruvate molecules Kreb’s Cycle 6 NADH, 2FADH , and 2 2TP per glucose o Step 1: Acetyl coA is combined with oxaloacetate OAA to produce citrate o Step 2: Citrate is oxidized to produce NADH and CO to pro2 ce 4 carbon Succinate; the 2 original Carbon for acetyl coA are conserved o Step 3: OAA is regenerated, in the process NADH, FADH , and GTP2(all high energy molecules) Electron Transport and Oxidative Phosphorylation o Oxidative Phosphorylation is the oxidation of high energy electron carrier (NADH and FADH ) 2 o They use 5 electron carriers 3 are large protein carriers found imbedded in the inner mitochondrial membrane= cytochromes they pump protons out of matrix 2 are small mobile electron carriers Start from the left to right 1 NADH dehydrogenase (coenzyme Q reductase)= it “reduces” NADH’s power 2 coenzyme Q reductase= ubiquinone get the electrons and passes them along 3 cytochrome C reductase 4 cytochrome C small hydrophilic protein 5 cytochrome C oxidase pump to the final electron accepter (oxygen) Energy equivalency o NADH 2.5 ATP o FADH 1.2 ATP o GTP1 ATP Energy formations: o Glycolysis 5 ATP (eukaryotes) 7 ATP (prokaryotes) o PDC 5 ATP o Kreb’s Cycle 20 ATP o Total 30 ATP (eukaryotes)/ 32 ATP (prokaryotes) Anaerobic (no oxygen) conditions: o ETC cannot function, and the limited supply of NAD becomes entirely converted to NADH, so glycolysis still occurs but instead of PDC, pyruvate continues to the fermentation process o Fermentation two types: (1) reduction of pyruvate to ethanol and (2) the reduction of pyruvate to lactic acid. OTHER Metabolic pathways: o Glycogenolysis Glycogen (polymer of glucose) breakdown, in animal stored as carbohydrates Opposite of glycogenesis Regulated through hormone (glucagon) when blood sugar level are low o Gluconeogenesis When no glucose is available Produces glucose by using lactate, pyruvate and Krebs cycle intermediates 11 step process “glycolysis in reverse” o Pentose phosphate pathway (PPP) Diverts from G6P in glycolysis, in order to form ribose5phosphate to synthesis nucleotides Makes NADPH similar to NADH, helps neutralize oxygen species G6P dehydrogenase primary point of regulations vital human enzyme (deficiency= can lead to death/hepatic complications) Metabolic regulation instead of working at the same time futile cycling, the work in tight regulation called reciprocal control o Regulation of glycolysis and gluconeogenesis: Two regulating enzymes: phosphofructokinase (PFK) and fructose 1,6 biphosphatase (F1,6BPase): opposing roles in glycolysis and gluconeogenesis Allosterically regulated o Regulation of the Krebs Cycle Enzyme: isocitrate dehydrogenase changes based on energy need (high + NAD , will increase AcetylcoA) Pathway Enzyme Positive regulators Negative regulators Glycolysis Phosphofructokinase fructose 2,6 ATP biphosphatase + AMP Gluconeogenesis fructose 1,6 fructose 1,6 biphosphatase biphosphatase + AMP Krebs Cycle isocitrate ADP ATP+NADH dehydrogenase Ketogenesis o During period of starvation glycogen stores become exhausted and blood glucose falls In response liver makes ketone bodies via Ketogenesis Can be formed into acetylcoA Example is type I diabetes ketoacidosis (low blood sugar)