Bioenergetics, Enzymes And Metabolism Flashcards
Define Transduction
Transformation of energy from one form to another
Define Exothermic
Flow of energy from the systems surroundings (out put of energy)
Define Endothermic
Flow of energy from the systems surroundings (input of energy)
Define system
A sub component of the universe
What are the 2 laws of Thermodynamics?
1st Conservation-energy cannot be created or destroyed only changed
2nd Direction-events move towards states of lower energy and greater disorder (entropy)
What is free energy and what does it tell us?
The measure of energy available to do work
Tells us how much energy is needed, or released by the system
States that are _______ have high energy
Unstable
States that are are stable have ______ energy.
Low
How does Delta G work in a system?
Amount of energy in our system
Delta G=Gb-Ga
Where is the energy Gb and Ga located? (5)
- chemical bonds
- accumulated charges
- ordered system
- intrinsic energy
- measured in calories
Delta G can have 3 values what are they?
Positive
Negative
Zero
A negative Delta G means?
The system releases energy (exergonic)
The reaction is considered spontaneous/favorable
A positive Delta G tells us?
The system requires energy (endergonic)
The reaction is considered non-spontaneous/unfavorable
A Delta G at zero tells us?
The system is at equilibrium
What is coupling?
Ability of an enzyme to link an energy consuming reaction (endergonic) with an energy releasing reaction (exergonic) to allow a reaction to proceed.
What does any enzyme need? (4)
- active site
- substrate
- specificity
- catalytic power
What is an active site?
Binding site in which ligands go to be acted on
How do enzymes increase rates up to a million times?
By controlling the components of the chemical reactions
- stabalizing/inducing charges
- stressing/aligning substrates
- reduce the entropy of the system
What are the 3 types of inhibitors?
- Competitive
- Noncompetitive
- Irreversible
Tell me about competitive inhibition?
- inhibitor looks like a substrate and competes for the active site
- inhibitor cannot be catalyzed by the enzyme
What does competitive inhibition do to the values of Km and Vmax?
Km increases
Vmax does not change
What is Noncompetitive (Allosteric) inhibition?
- inhibitor does not look like substrate
- binds at a different site, not the active site
What do Noncompetitive inhibitors do to the values of Km and Vmax?
Km remains unchanged
Vmax drops
What happens in irreversible inhibition?
Binds very tightly often covalently, decreases all activity of the enzyme
What does a catabolic pathway do?
Breakdown materials to release energy or form building blocks
Converge to common metabolites
What are metabolites?
Intermediate substances in each step of a pathway
What does an anabolic pathway do?
Uses energy to construct macromolecules from building blocks
What is Oxidation?
The loss of electrons
What is reduction?
The gaining of electrons
Where does energy come from?
- carbohydrates
- proteins
- Nucleic acids
- fats
What to know about glycolysis?
Can consume 2 ATP per glucose Can generate 4 ATP per glucose Can generate NADH Can occur in the absence of oxygen Releases lactic acid Consumes NADH produced
What are some high energy compounds? (3)
ATP
NADH(used for energy systems)
NADPH(used in biosynthesis)
Photosynthesis, plugging in a clock, and heat released during muscle contraction are all examples of what?
Transduction
What is true regarding active sites? (4)
- the importance of the individual side chains of the active site can be evaluated by site-directed mutagenesis
- the structure of the active site accounts not only for catalytic activity of the enzyme, but also for specificity
- active site and substrates have complementary shapes
- active site is typically buried in a cleft or crevice that leads from the aqueous surroundings into the depths of the protein
__________ are reversible inhibitors that compete w/a substrate for access to the active site of an enzyme.
competitive inhibitors
_________ lead to the synthesis of more complex compounds from simpler starting materials.
Anabolic pathways
The more ____________ that can be stripped from a fuel molecule, the more ATP that can be produced.
Hydrogen atoms
The magnitude of __________ indicates the maximum amount of energy that can be passed on for use in another process but tells us nothing about how rapidly the process will occur.
Delta G
What are true of catalysts?
- they are not altered irreversibly during the reaction
- they are required only in small amounts
- they have no effect on the thermodynamic of the reaction
The conversion of metallic iron (Fe) to ferrous state (Fe2+) in which the iron atom loses a pair of electrons, thereby attaining a more positive state is said to be _______.
Oxidized
All chemical reactions within a cell are reversible, and therefore the must consider two reactions occurring simultaneously, one forward and the other in reverse. According to the _____________ the rebate of a reaction is proportional to the concentration of the reactants.
Law of Mass Action
Since each enzyme molecule is only able to catalyze a certain number of reactions in a given amount of time, the velocity of the reaction approaches a maximal rate as the substrate concentration increases. The substrate concentration at which the reaction is at half-maximal velocity is called ____________ and has the symbol Km.
Michaelis Constant
What is meant in terms of concentration ratios when the Delta G of ATP hydrolysis in the cell is approximately -12kcal/mol, whereas Delta Gā is 7.3kcal/mol?
-the ratio of ATP/ADP in the cell is much greater then that at standard conditions.
A Noncompetitive inhibitor does not prevent the enzyme from binding its substrate. What will be the effect of increasing the substrate concentration in the presence of a Noncompetitive inhibitor? Do you expect a Noncompetitive inhibitor affect the enzyme Vmax? Km?
-the Km would be unaffected and the rate of the activity will increase towards the new Vmax.
What is an example of Allosteric modulation?
Feedback inhibition
_________ is the total chemical reactions occurring within the cell.
Metabolism
In the cell, energy from ATP hydrolysis may be used to? (4)
- drive unfavorable chemical reactions
- donate a phosphate group to a protein
- concentrate a particular solute within the cell
- separate charge across a memebrane
Pyruvate the end product of glycolysis, is a key compound because it stands at the junction between anaerobic and aerobic pathways. In the absence of molecular oxygen, pyruvate is subjected to ________.
Fermentation
The further a reaction is kept away from ___________ the more capacity it has to do work.
Equilibrium state
What two parameters are we most interested?
Maximal Velocity (Vmax) Strength of binding of the substrate for the enzyme
Michaelis Constant (Km)
(Km= k2+k3/k1)
Concentration of [S] required for 1/2 maximal activity an enzyme
Estimate of strength of binding
Michaelis-Menten Equation:
Velocity(V)=Vmax[S]/[S]+Km
If Km is a small number:
- it takes low levels of [S] to fill the active site and the ES complex is strong (inverse relationship)
- enzyme has HIGH affinity for the substrate
If Km is a large number:
- take high levels of [S] to fill active site and ES complex is weak
- enzyme has LOW affinity for the substrate
Km is analogous to Affinity why?
It allows comparison of enzymes and prediction of enzyme kinetic based on cellular concentrations of substrates
Equation Rearrangement to find Km:
Km=(Vmax[S])/(V)-[S]
What kind of bond is formed between enzyme and substrate why?
Noncovalent, this allows the release of product after the enzyme has catalyzed the reaction. Breaking of covalent one could be too energetically unfavorable and the product may not be released.
What is a feedback loop and how does it work?
When an end product effects production either positively or negatively
Define Energy
Capacity to do work, instability of a system
How is entropy decreased in an organism?
They increase the entropy of their environment. Simple molecules are ordered into complex molecules these complex molecules are then converted into smaller less ordered compounds and are then released into the environment.
