CH 8 Flashcards
Intro to metabolism
Metabolism
-Totality of an organism’s chemical reactions
Metabolic pathway
-Begins with a specific molecule ends with a product
-each step catalyzed by a specific enzyme
Catabolic Pathways
-release energy by breaking down complex molecules into simpler compounds
-EX. cellular respiration
Anabolic Pathways
-consume energy to build complex molecules from simpler ones
-EX. the synthesis of proteins from amino acids
Bioenergetics
-the study of how energy flows through living organisms
energy
-the capacity to cause change
-various forms, some can perform work
Kinetic energy
-energy associated with motion
Thermal energy
-kinetic energy associated with the random movement of atoms or molecules.
Heat
-thermal energy in transfer between objects
Potential energy
-energy that matter possesses because of location or structure
Chemical energy
-potential energy available for release in a chemical reaction
Thermodynamics
-the study of energy transformations
isolated system
-unable to exchange energy or matter with surroundings
-EX. liquids in thermos
open system
-energy and matter can be transferred between the system and its surroundings
-EX. organisms
First law of thermodynamics (principle of conservation of energy)
-the energy of the universe is constant
-energy can be transferred and transformed but cannot be destroyed or created
Second law of thermodynamics
-every energy transfer or transformation increases the entropy of the universe
Entropy
-measure of molecular disorder, or randomness
spontaneous processes
-occur without energy input
-can happen quickly or slowly
-must increase entropy in universe
nonspontaneous processes
-decrease entropy
-will only occur if energy is provided
Free energy
-energy that can do work when temperature and pressure are uniform
Exergonic reaction
-proceeds with a net release of free energy and is spontaneous
Endergonic reaction
-absorbs free energy from its surroundings and is nonspontaneous
Energy coupling
-use of an exergonic process to drive an endergonic one
-cells use it to manage energy recourses
-mediated by ATP
ATP (Adenosine triphosphate)
-cells energy shuttle
-composed of a ribose, adenine, and three phosphate groups
phosphorylated intermediate
-recipient molecule
Catalyst
-a chemical agent that speeds up a reaction without being consumed by the reaction
Enzyme
-a catalytic protein
-EX. sucrase, an enzyme that catalyzes
Activation energy
-the initial energy needed to start a chemical reaction
-also called, the free energy of activation
Catalysis
-enzymes or other catalysts speed up specific reactions by lowering activation energy
Substrate
-reactant that an enzyme acts on
Enzyme-substrate complex
when enzymes bind to its substrate
Active site
-the region on the enzyme where the substrate binds
Induced fit
-brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
Cofactors
-nonprotein enzyme helpers
-may be inorganic or organic
Coenzyme
-organic cofactor
-EX. vitamins
Competitive inhibitors
-binds to the active site of an enzyme, competing with the substance
Noncompetitive inhibitors
-bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
Allosteric regulation
-may either inhibit or stimulate an enzyme’s activity
-occurs when a regulatory molecule binds to a protein at one site and affects the proteins function at another site
Cooperativity
-form of Allosteric regulation that can amplify enzyme activity
Feedback inhibition
-the end product of a metabolic pathway shuts down the pathway
-prevents cells from wasting chemical resources by making more than needed
