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exam 2: chapter 6-metabolism
Terms in this set (82)
The energy that sustains most of earths life form comes from
The study of energy through a flow system
Refers to all chemical reactions of a cell or organism
Series of biochemical reactions that converts one or more substrates into final product
metabolic pathway (ex. Photosynthesis and cellular respiration)
Energy from sun is captures during photosynthesis to covert
CO2 and h2o to glucose
The energy stores in glucose released during cellular respiration rates
CO2 and h2o
Small molecules are assembled into large ones. Energy is required
Large molecules are broken down into small ones. Energy is released
What provides evidence that organisms evolved from common ancestors?
All types of life share some of same metabolic pathways
As organisms evolved, they developed ____
Specialized enzymes to help them adapt to their environments
Ability to do work
Objects in motion have
Objects that have potential to move have
Energy stores in chemical bonds (potential); energy released (kinetic)
Example of potential and kinetic energy in cells
Energy of chemical/electrochemical gradients across the plasma membrane
The potential energy stored in the chemical bonds of gasoline is used for what?
It is transformed into kinetic energy that allows the car to go
Amount of energy available to do work (usable energy)
Gibbs energy equation
ΔG = ΔH - TΔS
Change in total energy of a system
Temperature in kelvin
Change in entropy
If energy is released, delta G must be what?
negative/less than 0
Spontaneous reactions that occur without the addition of energy
Products of these reactions have less free energy than substrates
If a chemical reaction requires an input of energy, then G
Is greater than 0
Products of these reactions have more free energy than substrates
The energy required for a reaction to proceed (hump in diagram)
Activation energy causes reactant to become contorted and unstable leading to what
Allows bonds to be broken or made
What is the unstable state during activation energy called?
Main source for activation energy in cell
How does heat help reactants?
It helps reactants reach their transition state
Activation energy is lower if
the reaction is catalyzed (catalysts speed up reactions)
How is the breakdown of gasoline in a car an Exergonic reaction?
A spark is required to provide sufficient heat to exceed the activation energy. Once the reaction begins, enough heat is released to drive additional reactions
study of energy and energy transfer involving physical matter
What are the two laws of thermodynamics?
1. Energy can't be created or destroyed
2. The second law of thermodynamics states that the transfer of energy is not completely efficient. With each chemical reaction, some energy is lost in a form that is unusable, such as heat energy. The result is increased entropy (disorder).
How is heat energy also lost?
When plants utilize sunlight during photosynthesis
What provides the energy for a cells endergonic reactions?
hydrolysis of ATP
Composed of an adenosine backbone with three phosphate groups attached
Nucleoside consisting of nitrogenous base adenine and a five carbon sugar, ribose
alpha, beta, gamma
Three phosphate groups
Bonds that link the phosphate groups are
High energy bonds
When the bonds are broken between the phosphate groups, what happens?
Products have lower free energy than reactants
What is the reaction for ATP hydrolysis?
ATP + h2o = adp + Pi + free energy
Delta g =
If atp is not coupled with an endergonic reaction
Energy is lost as heat
If atp is coupled with an endergonic reaction
Energy can be transferred to drive that reaction
Energy derived from Exergonic atp hydrolysis is used by the integral proteins to pump 3 sodium ions out and 2 potassium ions into the cell
Sodium potassium pump
Protein catalysts that speed up reactions by lowering the required activation energy
How do enzymes work?
They will bind with reactant molecules promoting bond breaking and bond forming processes
Are enzymes specific?
yes, very specific
reactant of an enzyme-catalyzed reaction
reactant of an enzyme-catalyzed reaction
Substrate molecules interact at the enzymes
Can enzymes catalyze variety of reactions?
Yes, in some cases two substrates bond together to form a larger molecule. In other cases molecule down into smaller product
Prevent and orient substrate
Reduce chemical activation energy
At active site, there is a mild shift in shape that optimizes the reactions
What do slight changes at the active site do?
Maximizes the catalysis
How is the shape of a protein determined?
sequence of amino acids
What is important for the enzymes function of binding with unique substrates?
Amino acids of active site
How is the cellular environment important for enzyme function?
1. Suboptimal temps can denature the enzyme (loss of shape)
2. Suboptimal ph can reduce substrate enzyme binding
How can the enzyme help the substrate reach its transition state?
1. Position two substrates so they align perfectly
2. Provide an optimal environment (acidic or polar)
3. Comfort/stress the substrate so it is less stable and more likely to react
4. Temporarily react with the substrate making the substrate less stable and more likely to react
After a catalyzed reaction, what happens to the enzyme?
The product is released and it becomes available to catalyze another reaction
Regulation of enzyme activity helps cells
control their environment to meet their specific needs (ex. Digestive enzymes work harder after you eat than when you sleep)
Enzymes can be regulated by
1. Modifications in temperature and/or pH
2. Production of molecules that inhibit or promote enzyme function
3. Availability of coenzymes or cofactors
Have a similar shape to the substrate, competing with the substrate for the active site
Bind to the enzyme at a different location causing a slower reaction rate
Slow reaction rates but do not affect maximal rate
Slow rates and reduce maximal rate
Speed of a reaction when substrate is not limited
modify the active site of the enzyme so that substrate binding is reduced or prevented
Modify the active site of the enzyme so that the affinity for the substrate increases
Inorganic ions that some enzymes require to function. Work with enzymes in order to function (get them through diet)
cofactors (ex. Fe++, mg++)
Organic molecules including atp, NADH+, and vitamins that some enzymes need to function (get them from diet)
Where the end product of the pathway inhibits an upstream step, an important regulatory mechanism in cells (ex. ATP is an allosteric inhibitor for some enzymes involved in cellular respiration)
How do pharmaceutical drugs work?
They alter the binding site of the enzyme that is causing pain which will reduce the pain. Drugs are target for the enzyme in order to reduce pain, fever, etc
Series of reactions catalyzed by multiple enzymes
Which of the following molecules is likely to have the most potential energy?
Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule.
Which of the following is not true about enzymes?
- they don't change a reactions G value
- they are usually made of amino acids
- they lower the activation energy of chemical reactions
- none of the above (correct)
none of the above
An allosteric inhibitor does what?
Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate
Enzymes are catalysts that lower which type of energy?
why is energy coupling necessary?
ensures the energy generated in the first reaction does not go to waste as heat. Instead, it can be used as fuel for the second reaction that requires energy
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