Chapter 24 study guide PDF

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Study outline: Chapter 24. Metabolism What is an anabolic reaction? What is an example? Synthesis of larger molecules from simpler reactants Example: protein synthesis What is a catabolic reaction? What is an example Breakdown of larger molecules into smaller ones Example: cellular respiration What are the three types of metabolic reactions that occur in the body/cell? What is the definition of each? 1. Hydrolysis (breakdown) and condensation (dehydration) 2. Phosphorylation (adding phosphate) and dephosphorylation (removing phosphate) 3. Oxidation- reduction: transfer of electrons and hydrogens

What is an endergonic reaction? Is energy required or released during an endergonic reaction? Do the products contain more or less energy than the initial reactants? What is an example of an endergonic reaction? Anabolic (synthesis of proteins from amino acids) Energy in reactants < energy in products Energy input required Reactants + energy  products What is an exergonic reaction? Is energy required or released during an exergonic reaction? Do the products contain more or less energy than the initial reactants? What is an example of an exergonic reaction? Catabolic (breaking down proteins into shorter polypeptides or amino acids = protein catabolism) Change in potential energy Energy in reactants > energy in products Reactants  products + energy Released energy may power an energy- requiring reacting we call this “energy coupling” Which type of reaction, endergonic or exergonic, are anabolic or catabolic reactions? Endergonic = anabolic Exergonic = catabolic Negative ∆E (change in energy during the reaction) is associated with which type of chemical reaction endergonic or exergonic? How about a positive ∆E? Negative: exergonic Positive: endergonic What is the activation energy barrier? How is this barrier overcome in the cell?

(exergonic reactions are not spontaneous in the body) Is the energy required to start a reaction, enzymes are proteins that bind to a molecule, or substrate, to modify it and lower the energy required to make it react What are trace metals and coenzymes? How do they facilitate chemical reactions? Coenzymes: organic molecules derived from vitamins that transfer chemical groups during chemical reactions Example: NADH, FAD Trace Metal: allow the substrate to bind the active site Example: Mg, Fe, Cu, Zn Which vitamins (B3, B2, B5) serve as which coenzymes in metabolism? B3 = niacin B2 = riboflavin B5 = pantothenic acid What is ATP? What is ATP’s role in energy coupled reactions? (adenosine tri- phosphate) Essentially the energy currency of the body, it is the breakdown of ATP that releases energy which the body’s tissues such as muscle can use ADP is combined with a phosphate to form ATP in the reaction, ADP + Pi + free energy  ATP + H20, the energy released from the hydrolysis of ATP into ADP is used to perform cellular work (usually by coupling the exergonic reaction of ATP hydrolysis with endergonic reactions) donate energy Glucose oxidation: the central reaction of energy metabolism About how much of the energy in a molecule of glucose is available to do work in the cell and how much is lost as heat? About 1/3 capture 2/3 loss of heat

What is the initial substrate for glycolysis? What is the product of glycolysis? Where in the cell does glycolysis occur?

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Glucose 2 molecules of pyruvate anaerobic occur in the cytoplasm

Does glycolysis require oxygen? What do we call processes that do not require oxygen? What do we call processes that require oxygen? No energy required Anaerobic: without oxygen Aerobic: with oxygen Is carbon dioxide produced by glycolysis? How many molecules of ATP are gained in the cell for each glucose molecule from glycolysis? What coenzyme is produced by glycolysis?   

No carbon dioxide produced by glycolysis 2 molecules of ATP are gained Coenzyme produced = 2 molecules of NADH

Where does the pyruvate from glycolysis go if there is sufficient oxygen in the cell? Mitochondria Where does the Krebs cycle occur? How many molecules of ATP are made per glucose that entered the cell from the Krebs cycle? What is the main function of the Krebs cycle? What is the initial substrate?  Inside matrix of mitochondria  Molecules of ATP = 2 ATP  Main function: transfer electro hydrogen  FAD  Initial substrate: acetyl group Cyclical metabolic pathway that uses acetyl CoA as the initial substrate (reactant) and reduces coenzymes NAD+ and FAD All carbon from pyruvate leaves mitochondria as CO2, electrons transferred to electron carriers: NADH, FADH2 Where are all of the carbon dioxide molecules formed from the carbons that were initially part of glucose molecule? Mitochondria, 6 carbon molecules 1 glucose = 6 carbon dioxide

Where are the molecules of the electron transport chain located? As electrons, donated from NADH and FADH2, move through the electron transport chain, what ions are pumped from the matrix to the intermembrane space?

Located: inner mitochondria matrix Ions pumped: hydrogen ions

What is oxidative phosphorylation? What enzyme is responsible for the synthesis of ATP in the mitochondrion as a result of the diffusion of hydrogen ions from the intermembrane space to the mitochondrial matrix? What is the final electron acceptor of the electron transport chain? What product is formed as a result? The synthesis of ATP by phosphorylation of ADP for which energy is obtained by electron transport and which takes place in the mitochondria during aerobic respiration  Atom of oxygen = molecule of water  Molecules undergo oxidation/reduction reactions from high to low energy  Energy released is to pump H+ from matrix to intermembrane space  Last electron acceptor = oxygen Lactic acid fermentation: If oxygen is absent in the cell, how does the cell continue to make ATP? What is the substrate for this process and what is the product? 

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Low oxygen availability o Electrons transport chain back up o Krebs cycle stops Glycolysis can continue only if cytoplasmic NADH is in oxidized form (NAD+)

Which process is more efficient at synthesizing ATP from the breakdown of glucose, glucose oxidation or lactic acid fermentation? Glucose oxidation How many calories per gram are released as a result of catablyzing carbohydrates, proteins, or fats? Carbohydrates: 4 kcal/gram Proteins: 4 kcal/gram Fats: 9 kcal/gram If the body has sufficient stores of ATP on hand, what is done with excess glucose – short term? How about long-term? Short term: synthesis glucose Long term: synthesis fat

What is gluconeogenesis? What is its function? Where does it occur in the body? Gluconeogenesis: synthesis of new glucose from non-carbohydrate sources Function: insures a supply of glucose for central nervous system

Occurs: liver, small extent in kidneys Substrates:  Glycerol  Lactate  Amino acids

Energy Storage:  Most energy is stored as triglycerides  Most triglycerides stored within adipose cells...