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Bio Test 4
ATP
| Question | Answer |
|---|---|
| Anabolic Pathway | Consumes energy to make complicated molecules from simpler ones: making proteins from amino acids |
| Catabolic Pathways | Breaking down complicated molecules to simpler ones--cellular respiration |
| Is anabolic pathway endothermic or exothermic? | Endothermic |
| Is catabolic pathway endothermic or exothermic? | Exothermic |
| Kinetic Energy | Energy of motion |
| Potential energy | Energy that is available to do work, and is based on location and structure--it is the energy stored by matter |
| Give an example of Heat or Thermal Energy | random movement of atoms |
| Give an example of chemical energy | The break down of food |
| Energy | ability to rearrange a collection of matter |
| What are the laws of thermodynamics? | Energy cannot be created or destroyed, but transferred. The second law is that every transfer must increase entropy of the universe |
| How do the laws of thermo apply to biology? | Biologist want to understand the chemical reactions of life; which ones are exothermic or endothermic. |
| How do biologists figure out which reactions are endothermic or exothermic? | They assess the energy and entropy changes in the entire universe for seperate reactions |
| Entropy | Disorder, must be increased |
| Free Energy: | measures a system's instability--its tendancy to change to a more stable state |
| Delta H | Change in system's enthalpy (total energy) |
| Delta S | Change in entropy |
| Because a system has less free energy in its final state, will it be more likely or less likely to change at that point? | Less likely |
| What is the relationship between free energy and stability? | As free energy decreases, stability increases |
| Complicated sugar molecules | want to be broken down into simpler, stabler molecules |
| As a reaction proceeds toward equillibtium, what happens to the free energy of products and reactents? | They decrease |
| Stability: | Less free energy, doesn't want to change, borken down |
| Equillibrium: | Systems naturally want to decrease in free energy to become more stable and decrease work capacity |
| Exergonic Reaction; | Where energy is released |
| Endergonic reaction: | Where energy is gained |
| Reactions in a closed system are eventually going to reach | equillibrium |
| Chemical reactions of metabolism are and they would reach if they occured in the isolation of a test tube | reversible; equillibrium |
| At eqillibrium, is the cell able to or unable to do work? | Unable to do work, so it's dead |
| A cell is an open or closed system? | An open system |
| What are the three functions of ATP? | Transport work, mechanical work, and chemical work |
| What is important to note about catabolic pathways? | Reactions products provide the power of the next reaction;...a series or reactions |
| Give an example of each of the three types of work that ATP must perform | MechanicaL: Beating of cillia, contraction of muscle cells Transport Work: Pumping substances accross membrane Chemical Work: Pushing endergonic reactions--synthesis of polymers |
| Energy Coupling: How fast does ATP act in this case? | Using an exothermic process to drive an endothermic process. ATP is an immidiate source of energy |
| The structure of ATP contains...what? | A ribose sugar (like pentose, so it's the lone ring), three phosphate groups, and the nitrogenous base adenine |
| Hydrolysis: (What kind of a reaction is this?) | Allows the bonds between the three phosphate groups to be broken to exothermically force a phosphate to leave |
| When, with respect to ATP, can you be certain a reaction is spontaneous? | When ATP is involved |
| How is ATP able to perform work? | With the help of enzymes, the cell couples the enrgy of ATP to endothermic processes through the breaking of the phosphate bonds |
| Phosphorelated? | The recipient of the phospate group broken off from ATP. This is more reactive than the original unphosphorylated molecule |
| How does ATP perform mechanical work? | Atp phosphorlyates motor proteins |
| How does ATP perform transport work: | ATP phosphorylates transport proteins |
| How does ATP perform chemical work: | ATP Phosphorylates key reactents |
| How does ATP drive cellular work? | It powers certain molecules by phosphorylization perform work, and it is replenished by cellular respiration |
| How does ATP get regenerated? | Energy released by breakdown reactions in the cell is used to phosphorylate ADP; regenerate it to ATP. |
| Catalyst: | A chemical agent that speeds up a reaction without being consumed in the process |
| Enzyme: | catalystic proteins that speed up reactions by lowering the activation energy of a reaction |
| Activation Energy: | The energy that needs to be overcome so the downhill reaction can begin. |
| What is the standard three letter ending for an enzyme? | ase-----sucrase... |
| What are the two processes involved with chemical reactions? | Bond breaking and bond forming |
| What does changing one molecule into another involve? | transforming the reactent into a highly unstable state before the reaction can begin--the key ring analogy |
| In order for molecules to reach the transforming state where bonds can change.... | they need to absorbd energy from surroundings |
| How do enzymes lower the activation energy? | Enzymes enable the reactant to absorb enough energy to reach the transition state, cannot make an endothermic reaction exothermic, Enzymes simply incrase the rate of reaction |
| Enzymes are very selective...why does this matter? | they determine which chemical processes will be going on in the cell at a certain time |
| Substrate: | The enzyme acts on this |
| Enzymesubstrate complex: | When an enzyme binds to substrate |
| When the enzyme and substrate are bound, what happens to the substrate? | The enzyme converts it into the product of a reaction |
| Substrate Specificity: and give an example | The ability of an enzyme to recognize its substrate amoung isomers Sucrase will only act on sucrose not maltose |
| Active Site: and what is its shape | Where the enzyme molecule binds to the substrate. It is usually a picket or groove |
| Talk about the shape of an enzyme with respect to its active site | When a substrate enters the active site, interactions between the amino acids of proteins (that make up an enzyme) and chemical groups force the enzyme to alter its shape |
| Induced Fit: | Brings chemical groups into positions that enhance their ability to catalyze a chemical reaction |
| What are the first two steps of the catalytic cycle of an enzyme | Substrates enter active site; enzyme changes shape so induced fit exists. The second step is that substrates are held to active site by weak interactions, such as hydrogen bonds and ionic bonds |
| What is the third step of the catalytic cycle of an enzyme? | Active site can lower Eact and speed up a reaction by: orienting a substrate correctly, stretching and bending substrate bonds, providing a favorable microenvironment (by serving as a pocket of low pH in a neutrol cell), and covalently bonding to substrat |
| What are the final three steps of the catylitic cycle? | Substrates are converted into products, they are released, and the active site is now able to have two more substrates enter |
| What is the rate at which enzymes convert substrates into products | The more substrate available, the more frequently they mind to active site |
| What does it mean to have a limit to the rate adding more substrates | Eventually, the enzyme will be saturated, and the only way to increase rate of reaction is to add more enzymes |
| What are the three local conditions that alter enzymic activity? | Temp and pH, Cofactors, and Enzyme inhibitors |
| What is the optimal temp for human enzyme? Bacteria enzyme? | 40 degrees; 80 degrees |
| What is the optimal pH in stomach? In intestines? | 2; 8 |
| What are cofactors and how do cofactors alter the enzyme activity? | nonprotein helpers of enzymes that help catalyze reactions, maybe bound tightly to the enzyme permanently, may bind loosely and reversible the enyme along with the substrate, and can be inorganic (zinc, Iron, copper) |
| Co enzymes: and give an example | Cofactors that are organic, like vitamins |
| Enzyme inhibitors: | Selectively inhibit activity of an enzyme, (if attached with covalent bonds, irriversible) |
| What are the two types of enyme inhibitors | competitive inhibitors and noncompetitive inhibitors |
| nonCompetitive inhibitors: | do not directly compete with the substrate to bind to active site of enyme, can bind to other parts and changes the shape and function of the enyme--irriversible |
| competitive inhibitors: (and how can they be overcome) | compete to bind in the active site of an enzyme, are reversible. Bock the substrates ability to enter enzyme..can be overcome by increasing the concentration of substrate |
| How do cells regulate their metabolism? | either switching on or off genes that encode enzymes or by regulating the activity of the enzyme once it is made |
| Allosteric regulation | a protein's function at one site is affected by binding of a regulatory molecule at another site, most enzymes are like this |
| Allosteric activators and inhibitors: | regulatory molecules that change an enzyme's shape and the function of the active site by binding to a site elsewhere on the enzyme via noncovalent bonds |
| What are allosterically regulated enzymes made of? | two or more polypeptide chains or subunitis...where each subunity has its own active site |
| What happens when an allosteric activator binds to active form? | It stabillizes the active form? |
| What happens the inactive form binds with an inbititor? | stabilize the inactive form |
| When do activators and inhibitors dissociate? | At low concentrations |
| How does ATP bind to catabolic enzymes? | Allosterically |
| What happens when the supply of ATP is greater than demand? | the catabolism slows down ATP production, and binds same enzymes |
| Cooperativity: | Binding of one substrate molecule to active site of one subunit locks all subunits in active conformation. |
| Cooperativity serves to increase or decrease enyme activity? | increase |
| Feedback inhibition: and give an example | a metabolic pathway is switched off by the inhibitory bindoing of its end product to an enzyme that acts early in that pathway. ATP allostratically inhibits an enzyme in an ATP generating pathway resulting in its own feedback inhibition |
| Enzyme localization: | Enzymes can be grouped into complexes, incorporated into membranes and organelles , and inside the organelles are enzymes that carry out specific functions |
| Energy usually escapes in what form? | Heat |
| Fermentation: | partial degradation of sugars that occurs without the use of oxygen |
| Cellular respiration: | most important catabolic pathway, and occurs when oxygen is present and gets consumed (mostly in mitochondria) |
| Redox reactions | Transfer electrons from one reactent to another by oxidation and reduction reactions |
| Oxidation: | Loss of electrons |
| Reduction: | Gain of electrons |
| Reducing Agent | Electron donor |
| Oxidizing Agent: | Electron acceptor |
| Why are organic molecules a good source of fuel? | H bonds are a source of hilltop electrons |
| During oxidation reactions, what comes along with electrons? | Protons |
| Nad+ | A co enzyme that accepts the hydrogens before they are passed to oxygen |
| What does NAD+ function as? | It functions as an oxidizing reagent |
| How does NAD+ accept electrons? | Dehydrogenases remove a pair of hydrogen from a substrate, it delivers two electrons along with one proton ot its coenyme NAD+...and the leftover proton is released as a hydrogen ion into the surrounding solution |
| NADH | Reduced form of NAD+, passes the elctrons to the electron transport chain |
| Electron transport chain: | Passes electrons in a series o steps by using electron transfer energy to form ATP |
| What are the three states of cellular respiration? | Glycolysis, citric acid cycle, and oxidative phosphorylation |
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talkglitter2486
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