Energy and Enzymes Flashcards
Define enzyme
a catalyst that speeds up chemical reactions
what enzyme catalyses the removal of a phosphate group from most molecules
phosphotase
What is the central mechanism for most intracellular communication
removal of a phosphate group
What type of reactions do enzymes play a key role in
Metabolic reaction (eg. growth, reproduction, respond to stimuli, movement)
Define energy
the capacity to do work or transfer heat
what is the kinetic energy of electricity
flow of e-
what is kinetic E
the E of movement; the E possessed by and object in motion
Define potential energy
E stored in objects giving them the capacity for work; E an object has bc of its chemical structure or position
Where is Ep stored within mlcls
within bonds between atoms of that moleculew
As e- move closer to the atomic nucleus, the atom…
loses Ep
What is the first law of thermodynamics
Energy can be transformed from one form to another but it cannot be created or destroyed
what is the second law of thermodynamics
every energy transfer or transformation makes the universe more disordered or increases entropy
define entropy
the tendency of energy to become dispersed and spread out
Biological systems transfer E from what two main sources?
light and catabolism
what is the main E driver in biological systems
photosynthesis
define Catabolism
the chemical breakdown of organic and inorganic molecules
define enthalpy
the heat content of a system (△H)
△H=
△Hproduct - △Hreactant
enthalpy reflects
the number and kinds of chemical bonds that exist between atoms
what is the overall △H of an endothermic reaction
positive
what is the overall △H of an exothermic rxn
negative
define spontaneous rxn
a reaction in which free E of the products is less than free E of the reactants
Spontaneous rxns tend to occur when…
a) reactions are exothermic
b) △Sproducts > △Sreactants
Entropy is increased when…
a) chem rxns result in an increase to the number of mlcls
b) when solids turn to liquids or when liquids turn to gas
Define free energy (△G)
the portion of a systems energy that can perform work when temperature is uniform throughout the system
△G=
△H-T△S
Define exergonic reaction
reaction where the free energy of the reactants ism greater than the free energy of the products
in exergonic rxns, is△G neg or pos
neg
are exergonic rxns energy consuming or energy releasing
energy consuming
what is another term for spontaneous reaction
exergonic process
define endergonic reaction
reaction where the free energy of the products is greater than the free energy of the reactants
In endergonic reactions is △G pos or neg
pos
are endergonic rxns energy consuming or energy releasing
consuming
Do endergonic or exergonic rxns result in a higher state of free E
endergonic rxns
what is the basis of an energy coupling rxn
production of E from exergonic rxn is available to run an endergonic rxn
do rxns tend to be more spontaneous when △S is pos or neg?
pos
define equilibrium
maximum stability of a rxn where △G=0, concentrations aren’t necessarily equal
