Lecture 10 Flashcards
how are polymers synthesized
dehydration
how are polymers broken down
hydration
what is a catabolic pathway
energy is released by the breakdown of complex molecules to simpler compounds; overall ΔG is negative
what is an anabolic pathway
energy is used to build complicated molecules from simpler ones; overall ΔG is positive
what is kinetic energy
the energy of an object in motion
what is potential energy
stored energy
what is thermal energy
kinetic energy associated with random movement of atoms or molecules
what is chemical energy
is potential energy availablefor release in a chemical reaction
what are the four forms of energy
light, electricity, motion, heat
what is the first law of thermodynamics
Energy can be changed from one form to another, but it cannot be created or destroyed
what is the second law of thermodynamics
Every energy transfer or transformation increases the disorder (entropy) of the universe
what causes a reaction to be spontaneous
the products are less ordered than the reactants; the products have less energy than the reactants
what does it mean for a reaction to be spontaneous
a process that can occur without an input of energy; must increase the entropy of the universe
how can a non-sponatanous reaction occur
can only occur if energy is added to the system
what does it mean when an reaction is exothermic
reactions release energy; the products have less potential energy than the reactants; spontaneous; more stable
what does it mean when an reaction is endothermic
reactions absorb energy; the products have more potential energy than the reactants; not spontaneous; less stable
how does a reaction end with a negative delta-G, the system must…
give up enthalpy, give up order, or both
what is free-energy
energy available to do work
what is ΔG
is a measure of a system’s instability – its tendency to change to a more stable state
what type of systems are living organisms
open systems
what is the ultimate source of energy for most organisms
the sun
a cell does what three main kinds of work
chemical, transport, and mechanical
why is ATP important
temporarily stores chemical potential energy that drives most cellular work
what is phosphorylation
Terminal phosphate group is transferred to a reactant molecule involved in an endergonic reaction
what are catalysts
chemical agent that speeds up a reaction without being consumed by the reaction
what is activation energy
The initial energy needed to start a chemical reaction is called the free energy of activation
how are enzymes beneficial to reactions
enzymes reduce activation energy and speed up metabolic reactions
what is the active site
The substrate interacts with a small pocket or groove in the enzyme molecule
how do enzymes lower activation energy
Bringing the reacting molecules together; Changing the shape of the substrate molecules; Providing a microenvironment that promotes catalysis; Participating directly in the chemical reaction
what determines enzyme activity
initial substrate concentration, environmental conditions, cofactors, enzyme inhibitors
what are cofactors
non-protein helpers
what are enzyme inhibitors
competitive and noncompetitive
what are competitive inhibitors
they bind to the active site of an enzyme, competing with the substrate- can be overcome by increase [substrate]
what are noncompetitive inhibitors
they bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
what is allosteric regulation
Enzyme’s function at one site is affected by the binding of a regulatory molecule at another site; activation and inhibitors
what is feedback inhibition
End product switches off the metabolic pathway
what is allosteric activation
enzyme binds allosteric activators; binding activator converts enzyme to high-affinity state; in high-affinity state, enzyme binds substrate
what is allosteric inhibition
enzyme binds allosteric inhibitor, binding inhibitor converts enzyme to low-affinity state; substrate is released
why is feedback inhibition important
prevents a cell from wasting chemical resources
