BIOL 209 1nd EditionExam # 2 Study Guide Lectures: 9-16Metabolism: change and chemical/physical workings of a cell- 2 parts: - Catabolism: larger molecules are broken down into smaller ones with the release of energy- Anabolism: AKA biosynthesis, larger molecules are built from smaller ones with the energy given off by catabolism… results in cell structuresEnzymes: examples of catalysts, which are chemicals that speed up a chemical reaction without becoming part of the products or being consumed in the reaction- Characteristics- Composed of protein- Lower activation energy of chemical reactions- Have unique shapes, specificity, and function- Provide a target site for substrates (enzymes are larger)- Can by recycled- Greatly affected by temperature & pH- Can be regulated- Enzymes do not actually add any energy to a reaction- 2 parts:- Simple protein- Conjugated (holozyme) protein (apoenzyme) & nonprotein molecules (one or more cofactors)- Apoenzyme and cofactor(s) either associated by covalent or noncovalent bonds - Cofactors are either organic molecules (coenzymes) or inorganic elements (metal ions)- Induced fit: enzymes help substrates move into active sites by slightly changing the shape- Coenzymes transfer chemical groups from one substrate to another- Vitamins are a common component of coenzymes- Metallic cofactors activate enzymes and bring enzyme/substrate together- Exoenzymes break down large molecules extracellularly- Endoenzymes function intracellularly- Constitutive enzymes have either repressed or induced production in response to substrate/product concentrationCondensation reactions: require ATP and release a water molecule for each bond madeHydrolysis reaction: addition of a water molecule to break a bond- Enzymes become unstable, or labile, when changes in normal conditions occur- Competitive inhibition: a mimic substrate effectively shuts down enzyme by occupying space but not releasing product- Regulatory/allosteric site: binding of molecules other than the substrate – changes shape of active site so substrate can’t enter- Negative feedback loop- Noncompetitive inhibition- Enzyme repression/induction based on cell demand/environmentForms of energy: thermal, radiant, electrical, mechanical, atomic, chemicalExergonic reaction: releases (produces) energyEndergonic reaction: requires energy to produce something- Extract chemical energy already present in nutrients of cellOxidation: the loss of electronsReduction: the gain of electrons- Together, they are a conjugate/redox pairHydrogen = singly proton and single electron  electron transfer- Carrier molecules shuttle electrons and hydrogens between substrates to facilitate the transferof redox energy- Coenzyme NAD+ is most common carrier – carries hydrogens and an electron pair- Others: FAD, NADP, coenzyme A - Electrons are passed to a final electron acceptor to complete a reaction- Aerobic metabolism = molecular O2- Anaerobic metabolism = other organic or inorganic compound- Cyclic process- Phosphorylation adds an inorganic phosphate to ADP, converting it to ATP- Oxidative phosphorylation: how most ATPs are formed – a series of redox reactions occurring during the final phase of the respiratory pathway- Substrate-level phosphorylation: ATP is formed by transfer of a phosphate group from a phosphorylated compound (substrate) directly to ADPCatabolism: a series of three pathways1. Glycolysis – 2 pyruvates per glucose, 4 ATPs – 2 = 2 ATPs- In cytoplasm of prokaryotes/eukaryotes2. Krebs Cycle - In mitochondrial matrix of eukaryotes & cytoplasm of bacteria3. Respiratory Chain (electron transport and oxidative phosphorylation)- In mitochondrial membrane of eukaryotes and cell mambrane of bacteria- Aerobic Respiration: converts glucose to CO2, produces H2O, and generates energy- O2 is final electron acceptor- Larger ATP amount (36-38)- Facultative and aerotolerant anaerobes only use glycolysis to ferment glucose- O2 not required (organic compounds are the final electron acceptors)- Small ATP amount- Glucose is a great hydrogen and electron donorGlycolysis: anaerobic process that converts glucose to pyruvate1. Glucose is phosphorylated by an ATP to prime the system- Glucose 6 P is produced2. G6P is converted to Fructose-6P (its isomer)3. An ATP phosphorylates first carbon of F6P- Fructose-1, 6 diphosphate is produced4. F16DP is plite into G3P and DHAP (isomers)- DHAP converted to G3P5. Both G3Ps become involved in redox of glycolysis- NAD+ picks up hydrogens from G3P, forming NADH- Single inorganic phosphate is added to G3P- DPGA is produced6. One P from DPGA is donated to ADP (sub-level phosphorylation)- 1 ATP is produced- 3 PGA is produced7, 8. 3 PGA Is coverted to 2 PGA and removal of a H2O from 2 PGA converts it to PEPA- Results in a high energy P bond9. Second ATP is produced (sub-level phosphorylation)- Pyruvic acid is produced – 2 pyruvatesKrebs Cycle1. Oxaloacetic acid (oxaloacetate – 4 C) reacts with acetyl group (2 C) on acetyl CoA- Citric acid is formed (citrate – 6 C)- CoA is released2. Citric acid is coverted to isomer, isocitric acid (isocitrate – 6 C)3. Isocitric acid is acted on by an enzyme with NAD+ or NADH- NADH or NADPH is generated - CO2 is split- Alpha-ketoglutaric acid is produced (Alpha-ketoglutarate – 5 C)4. Alpha-ketoglutaric acid – substrate… CoA involved- NADH produced- Succinyl CoA (4 C) is produced5. Succinyl-CoA = sub. Level phosphorylation- ATP produced in bacteria – CoA regenerated- GTP produced in eukaryotes- Succinic acid produced (succinate – 4 C)6. Succinic acid undergoes redox – FAD is electron & hydrogen acceptor- Succinyl dehdrogenase = enzyme in reaction - Found in membrane of bacteria & mitochondrial cristae of eukaryotes- FADH2 generated and enters ETS- Fumaric acid (fumarate – 4 C) is produced7. H2O + fumaric acid- Matlic acid produce (malate – 4 C)8. Malic acid is dehydrogenated- Final NADH is formed- Oxaloacetic acid is producedRespiratory Chain- Electron carriers: NADH dehydrogenase, flavoproteins, CoQ, & cytochromes- Sequence of electron carriers:1. NADH dehydrogenase2. Flavin mononucleotide (FMN)3. CoQ4. Cytochrome b5. Cytochrome c16. Cytochrome c7. Cytochrome a & a3- NADHs from glycolysis and Krebs cycle are set into ETS to start it off – each NADH = 3 ATP- FADH2 = 2 ATPs- ATP synthase complexes along cristae captures energy- Oxidative phophorylation: ATP synthesis + electron transportChemiosmosis: as electron transport carriers