Chapter 8 - Metabolism Flashcards
metabolism
the totality of an organism’s chemical reactions
Metabolism as a whole manages the material and resources of the cell
catabolic pathway
leads to the release of energy by the breakdown of complex molecules to simpler compounds
(ex. breakdown of sugars to release energy)
anabolic pathway
consume energy to build complicated molecules from simpler ones
(creation of glucose in plants or amino acids linked together to form muscle protein in response to physical exercise )
Energy
the capacity to do work
kinetic energy
Anything that’s moving possesses kinetic energy
potential energy
stored energy that results from position or structure
chemical energy
a form of potential energy that is stored in molecules
The amount of chemical energy a molecule possesses depends on its number of bonds
Thermodynamics
The study of energy transformations that occur in matter
The first law of thermodynamics
the energy of the universe is constant and can be transferred. It cannot, however, be created or destroyed.
The second law of thermodynamics
every energy transfer or transformation increases the entropy, or the amount of disorder or randomness in the universe
What does the free energy change of a reaction tell us?
Whether or not the reaction occurs spontaneously
Free energy
defined as the part of a system’s energy that is able to perform work when the temperature of a system is uniform
exergonic reaction
energy is released. Spontaneous (not necessarily mean quickly) and release free energy to the system
endergonic reaction
One that requires energy in order to proceed.
Endergonic reactions absorb free energy; that is, they require free energy from the system
Energy coupling
the use of an exergonic process to drive an endergonic one
Primary source for energy in cells in energy coupling:
ATP
Made of from the nitrogenous base Adenine bonded to ribose and a chain of three phosphate groups
When a phosphate group is hydrolyzed, energy is released in an exergonic reaction
ATP becomes what when one phosphate group is hydrolyzed
ADP
Enzymes speed up metabolic reactions by
lowering the activation energy
what is activation energy
the amount of energy requiems to start a reaction
the amount of energy it takes to break the bonds of the reactant molecules
WITHOUT changing the free energy change of the reaction
What is a substrate
The reactant that the enzyme acts on
active site
where the enzyme binds to the substrate
Enzyme and substrate form a complex called
enzyme-substrate complex
What kind of bonds hold together the enzyme-substrate complex
weak bonds such as hydrogen bonds
What are the substrates converted into
products which are then released by the enzyme
What are the factors that can affect the activity of an enzyme
pH & temperature
changes in the precise shape of an enzyme will usually mean that the enzyme will not be as effective
What are cofactor
nonprotein helpers that help the enzyme to function properly. Often include metal ions such as zinc, iron or copper
What is an organic cofactor called?
Coenzyme
Competitive Inhibitors
Compete with the substrate for the active site
Noncompetitive inhibitors
do not directly compete with the substrate molecule but impede with enzyme activity by binding to another part of the enzyme
This causes the enzyme to CHANGE SHAPE and renders the active site nonfunctional
allosteric site
Another specific binding site on the enzyme that is not the active site.
what binds to the allosteric site
enzyme regulators will bind to the allosteric site, changing its shape. This can either stimulate or inhibit enzyme activity
feedback inhibition
the end product of the enzymatic can switch off its pathway by binding to the allosteric site of the enzyme in the pathway
by turning it off when when the product accumulates in the cell it increases the efficiency of the pathway
prevents the enzyme from wasting materials by overproducing
open system
energy and matter can be transferred between the system and its surroundings
ORGANISMS ARE OPEN SYSTEMS
pH that most enzymes function best at
6-8
induced fit
change in the shape of the enzyme at the active site that is induced by the substrate
brings chemical groups at the active site into positions that enhance their ability to catalyze the reaction
