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62 Cards in this Set
- Front
- Back
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What is potential energy?
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Energy of position. (How much energy an object has the ability to have, for example, a book sitting on a shelf has more potential energy because of the energy it would have if it fell, as oppose to a book sitting on the floor)
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What do cells use energy for?
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•chemical work
•mechanical work •electromechanical work -electricity drives chemicals |
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What is the 1st Law of Thermodynamics?
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•total amount of energy in the universe remains constant
•energy can undergo conversions from one form to another, but it cannot be created or destroyed |
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What is the 2nd Law of Thermodynamics?
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•no energy conversion is ever 100% effective
•the total amount of energy is flowing from high energy forms to forms lower in energy |
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What is entropy?
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•measure of degree of disorder in a system
•cells are resupplied with energy from other sources |
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How do energy changes in cells tend to run?
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Spontaneously; in a direction that results in a decrease in usable energy (like going down a slide)
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What is an endergonic reaction?
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Energy input required, products contain the most energy
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What is an exergonic reaction?
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Energy is released, products have less energy than reactants (reactants have more energy)
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In which type of reaction is ATP "earned?"
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exergonic
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In which type of reaction is ATP "spent?"
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endergonic
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What is the relationship between energy and ATP?
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ATP transfers energy by one of three phosphate bonds breaking + forming new bonds
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When are electrons transferred?
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Electrons are transferred in virtually every reaction that harnesses energy for use in the formation of ATP.
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What are co-enzymes?
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"helper" molecules, assist in electron transfers
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What is an electron transfer?
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•necessary for formation of ATP, creation of energy
•electrons are transferred by a membrane |
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What is the role of the cell membrane?
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•site of arrangement of enzymes, co-enzymes
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What is concentration gradient?
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• the number of molecules or ions in one region is different than the number in another region
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What is a "down" gradient?
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when, in the absence of other forces, a substance moves from a more concentrated region to a less concentrated region
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What is diffusion?
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•simplest type of movement in a molecule
- the net movement of like molecules or ions down a concentration gradient (happens away from the place with the most collsions) |
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What is equilibrium NOT EQUAL to?
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no movement
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Steeper gradient results in...
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faster diffusion
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Smaller molecules result in...
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faster diffusion
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Higher temperature results in...
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faster diffusion (molecules aqcuire energy as heat is applied)
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What is the function of electrical or pressure gradients?
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chase molecules from one region to another
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What does the direction a reaction will run depend upon?
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product ratio, energy content of participants
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Nearly all chemical reactions are...
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reversible
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What is chemical equilibrium?
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energy in reactants is pretty much equal to energy in products (almost never exactly equal)
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What is a substrate?
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•molecule the enzyme acts upon
•reactant •intermediate |
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What is an enzyme?
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•speeds up the rate at which reactions (which will eventually happen anyway) approach equilibrium
-usually proteins •co-factors •are recycled AN ENZYME IS LIKE AN ALARM CLOCK! |
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What is a spontaneous reaction?
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• reaction occurs without input of energy
-will probably output heat ~slope of slide=spontaneous reaction (RELEASE OF ENERGY) |
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What is a non-spontaneous reaction?
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•input of energy
~the stairs leading to the top of the slide (ENERGY NEEDED) |
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How are substrates described in an induced fit model?
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•substrate molecules are brought together
•substrates are oriented in ways that favor reactions |
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How are active sites described in a induced fit model?
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•active sites may promote acid-based reactions
•active sites may shut out water |
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What is the induced fit model?
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mechanism that allows enzymes to function
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What is the active site?
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area where substrate-enzyme bonding occurs
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What dictates the ability of a substrate to bond with an enyme?
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shape
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The fit between substrate and enzyme is...
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conformational
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Substrate-enzyme bonds are least stable when they are in the...
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transition state
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What are the factors that influence enzyme activity?
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1. Temperature
2. pH 3. salt concentration 4. allosteric regulators 5. coenymes + cofactors |
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What happens when bonds break?
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the function is changed
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The breakage of the peptide bonds by temp, etc. which hold enzyme together break due to a process called...
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de-naturing (without native shape)
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What is a competitive inhibitor?
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Competes with the substrate for the active site
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The competitive inhibitor slows...
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the rate at which product is formed
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Excess substrate is added to a reaction to...
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overcome competitive inhibition
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What is allosteric activation?
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•changes to something that will allow substrate to bond
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Allosteric inhibitors...
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cause peptide bonds to change, changing the shape of the "substrate acceptor" so that substrate cannot remain bonded.
KICKS THAT SUBSTRATE OFF THE ENZYME! |
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What is feedback inhibition?
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when end product builds up, inhibits enzyme/substrate in pathway, more end products are no longer made.
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What effect does an increase in temperature have on enzymes?
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•increase in temperature ---> increase in molecular collisions (and therefore reaction rates)
•disrupts bonds and destroys shape of active site |
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What effect does pH have on enzymes?
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decrease in pH, increase in hydrogen ions
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The phospholipid membrane is non-polar, meaning it will attract...
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O2, CO2, H2O and other small non-polar molecules (like attracts like)
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These will not be granted entry into phospholipid membrane...
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large, polar, water soluble molecules
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molecules are granted entry into phospholipid membrane one at a time via...
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1. diffusion across lipid bylayer
2. passive transport 3. active transport |
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molecules are granted entry into phospholipid membrane via "bulk transport," examples of which are...
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1. endocytosis
2. exocytosis |
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What are transport proteins?
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• span the lipid bylayer
• change shape when they interract with solute •plays role in active/passive transport |
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What is passive transport?
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•protein opens to allow molecule in through an entry point in one side which closes once the molecule is being harbored by the protein. Then, exit point leading into cell opens to eject molecule (goes from areas of high concentration to low concentration)
•DOES NOT REQUIRE ENERGY INPUT •DIFFUSION REJECTS SMUGGLED IN THROUGH PROTEIN |
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What is active transport?
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•goes against concentration gradient, REQUIRES ENERGY INPUT via ATP!
• transport protein activated by ATP |
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What is the role of ATP in active transport?
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Changes shape of transport protein so that molecules are released at opposite membrane surface
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What is the definition of osmosis?
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• diffusion of WATER molecules across a selectively permeable membrane
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Direction of net flow of water in osmosis is determined by...
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concentration gradient
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In Osmosis, the side with the most solute molecules has the least...
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H20 concentration
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What does tonicity refer to?
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Relative solute concentration
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What is exocytosis?
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Molecules are escorted out of the cell via vesicles more than one molecule at a time
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What is endocytosis?
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Molecules are escorted into the cell via vesicles more than one molecule at a time
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