29 terms

Chapter 8

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What is metabolism?
the sum of the physical and chemical processes in an organism by which its material substance is produced, maintained, and destroyed, and by which energy is made available
What catalyzes metabolic reactions in the cell?
They are called enzymes; each one is specific for one metabolic reaction.
First law of thermodynamics
ENERGY CAN NOT BE CREATED OR DESTROYED, ONLY ALTERED IN FORM
Second law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe
Entropy
is how disordered or random matter is
Catabolic pathways
is the energy being released and they are downhill reactions
Anabolic pathways
require energy to build the complex molecule
Energy is being stored
They are the uphill reactions
Energy
is the capacity to cause change
Potential Energy
is energy that matter contains because of its location of structure (stored energy)
Kinetic Energy
is the energy of motion (release energy)
Chemical Energy
is the energy a molecule possesses because of the way the electrons in their bonds are arranged
Light energy
energy in photons can be converted to chemical energy such as photosynthesis
Thermal energy
heat is random movement of atom and molecules
What is free energy?
Is the measurement of a molecule's potential energy at uniform pressure and temperature
How do we calculate the change in free energy (G)?
G (final state) - G (initial state
What is exergonic reaction?
REactions in which the delta G is less than 0
Downhill
What is Endergonic?
Reactions in which the delta G is greater than 0
What is energy coupling?
raises the free energy of the reactants
ATP is hydrolyzed
ATP is regenerated energy from food
what is the process of regenerating ATP?
Reductive phosphorylation
How is ATP used to drive cellular work?
releasing free energy that can be coupled to other reactions
What is the activation energy barrier in reactions?
There is an energy barrier that separates the energy levels of the reactants and products. Energy must be added to the reactants to overcome the energy barrier, which is recovered when products are formed.
How can heat overcome the activation energy barrier?
Add heat. This will increase the average energy of the substance and enable more substance to overcome the barrier.

or Add a catalyst. Catalysts lower the activation energy by 'stabilizing the intermediate
What are enzymes?
Enzymes are proteins that acts as biological catalyst
They lower the energy of activation
Describe the energy profile of an exergonic reaction with and without enzymes.
then it would not lower the energy of activation
An Enzyme- substrate
complex forms when the stubstrate weakly bonds to the enzyme
It induces the enzyme's shape to shift and form more bonds to hold the substrate tighter
What are substrate
they are reactants that bind enzymes
How do enzymes help substrates reach the transition state?
the active site is the specific region of the enzyme that can bind the substrate
why is heat still a necessary component of the enzyme catalytic cycle?
...
Factors that influence enzyme activity
1) Temperature- as the temperature increases reactions move faster and enzyme will denature or deactivate the enzyme

2) pH affects the charge on those R-groups and can result in a change of shape for the enzyme

3) Cofactors are non- protein molecules that bind and assist enzymes. May bind permanently or transiently for the reaction

4) Enzyme inhibitors bind an enzyme and decreases its activity