lecture 10 Flashcards
What are competitive inhibitors?
they bind the active site of an enzyme, competing with the substrate
What are noncompetitive inhibitors?
they bind to another part of an enzyme, making the active site less effective
Which inhibitor competes with the substrate?
competitive inhibitor
Which inhibitor makes the active site less effective?
noncompetitive inhibitor
What are some examples of inhibitors?
toxins, poisons, pesticides, and antibiotics
What is Vmax on a Reaction Rate vs Substrate Concentration graph?
the saturation point for a particular amount of enzyme.
the maximal reaction rate when substrate is not limiting.
What is Km on a Reaction Rate vs Substrate Concentration graph?
substrate concentration at which reaction velocity is half maximal.
inversely related to enzyme affinity.
Compared to a normal enzyme on a graph: competitive inhibitors have the same __ but different ___.
same Vmax, different Km
Compared to a normal enzyme on a graph: noncompetitive inhibitors have the same __ but different ___.
same Km different Vmax
Definition of thermodynamics
the study of energy transformation
What is an isolated (closed) system?
A system is unable to exchange energy or matter with its surroundings
What is a closed system?
A system is able to exchange energy and matter between the surroundings
What is the first law of thermodynamics?
Energy can be transferred and transformed, but it cannot be created nor destroyed.
What is kinetic energy?
energy associated with motion
What is thermal energy?
kinetic energy associated with random movement of atoms or molecules
Are organisms and life an open or closed system?
Open
What is Potential energy?
the energy that matter possesses because of its location or structure
What is Chemical energy?
the potential energy available for release in a chemical reaction
True/False: Energy cannot be converted into other forms.
False. Energy CAN be converted into other forms
Total Entropy (S) can only increase in a ___ system.
isolated (closed)
True/False: During every energy transfer or transformation, some energy is unusable and is often lost as heat to the universe
True
What does the second law of thermodynamics state?
Every energy transfer or transformation increases the entropy of the universe
What property is associated with disorder?
Entropy (S)
What is entropy?
“waste heat” or energy loss, from heat engines and other mechanical devices which could never run with 100% efficiency in converting energy into work, a measure of molecular disorder or randomness
How do spontaneous reactions occur?
without energy input
What is the rate of spontaneous reactions?
quickly OR slowly
For a process to occur spontaneously, what must happen?
it must increase the entropy of the universe
What are nonspontaneous reactions?
Reactions that decrease entropy of a system
How do nonspontaneous reactions occur?
Only if energy is provided
What are anabolic processes?
When organisms create ordered structures from less organized forms of energy and matter
What are catabolic processes?
When organisms replace ordered forms of matter and energy in their surroundings with less ordered forms
The evolution of more complex organisms does not violate the ____ law of thermodynamics.
second
True/False: Entropy may decrease in a particular system, such as an organism, as long as the total entropy of the system and surroundings increases
True
What does the free energy change (G) of a reaction tell us?
whether or not the reaction occurred spontaneously
True/False: Spontaneous processes occur without energy input.
True
What is a systems free energy (G)?
energy that can do work when temperature and pressure are uniform, as in a living cell
What is the change in free energy related to during a process?
change in total energy (H), change in entropy (S), the temperature in Kelvin (T)
___ is negative for all spontaneous processes.
delta G
Processes with zero or positive deltaG are ____.
never spontaneous
What can spontaneous reactions be harnessed for?
to perfrom work
A systems free energy (G) is a measure of what?
the systems instability, its tendency to change to a more stable state
During a spontaneous change, free energy ___ and the stability of a system ____.
free energy decreases and the stability of a system increases
What is the only time a spontaneous reaction can occur?
When it is moving toward equillibrium
Does higher free energy mean more or less stable?
less
Does lower free energy mean more or less stable?
more
What happens when reactions in a closed system reach equillibrium?
They can do no more work
True/False: Cells are not in equilibrium. Why?
True, they are open systems experiencing a constant flow of materials
What is a defining feature of life?
metabolism is never at equilibrium
Are chemical reactions reversible or irreversible?
reversible
What do the two opposite-headed arrows indicate in reaction sequence
a reaction is reversible
When is chemical equilibrium reached?
when the forward and reverse reactions occur at the same rate
What is the concentration of reactants and products ta equilibrium?
they do not change
What is metabolism?
the totality of an organism’s chemical reactions, an emergent property of life that arises from orderly interactions between molecules
What does an organisms metabolism do?
transforms matter and energy
How does the metabolic pathway begin and end?
begins with a specific molecule and ends with a product
What do catabolic pathways do?
release energy by breaking down complex molecules into simpler compounds
What do anabolic pathways do?
consume energy to build complex molecules from simpler ones
What is an example of a catabolic pathway?
cellular respiration
What is an example of an anabolic pathway?
synthesis of proteins from amino acids
How does an exergonic reaction proceed?
with a net release of free energy and is spontaneous (Delta G negative)
How does an endergonic reaction proceed?
absorbs free energy from its surroundings and is nonspontaneous (delta G positive)
What is ATP?
adenosine triphosphate, cells energy currency
What is ATP composed of?
ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
How can the bonds between the phosphate groups of ATP’s tail be broken?
by hydrolysis
What happens when the terminal phosphate bond is broken in ATP?
energy is released
Where does the release of energy come from when the terminal phosphate bond is broken in ATP
the chemical change to a state of lower free energy, NOT from the phosphate bonds themselves
What does ATP power, and how?
ATP powers cellular work by coupling exergonic reactions to endergonic reactions
What are the 3 kinds of work cells do?
chemical, transport, and mechanical
What is chemical work in cells?
pushing endergonic reactions to be net exergonic reactions
What is transport work in cells?
pumping substances against the direction of spontaneous movement
What is an example of mechanical work in cells?
contraction of muscle cells
What is energy coupling?
the use of an exergonic process to drive an endergonic one
How do cells do work?
by managing energy resources by energy coupling
Majority of energy coupling in cells is mediated by ___.
ATP
Are coupled reactions endergonic or exergonic?
exergonic
True/False: Endergonic reactions can be coupled to exergonic ones to drive them forward.
True
What is phosphorylation?
transferring of a phosphate group to some other molecule, such as a reactant
What is a phosphorylated intermediate?
The recipient molecules of phosphorylation
What is the sign of G in phosphorylation?
negative
