Enzymes Flashcards
Define enzyme?
A protein biological catalyst that speeds up reactions,
- Breaks down macromolecules,
- Combines micromolecules
What is an active site?
The area is an enzyme that binds to a substrate
What is denaturing?
When an enzyme loses its shape from heat or PH change,
- This can be reversed by changing the environment back to optimum conditions because the shape of the enzyme is coded into the primary structure
What is induced fit?
The dynamic fit between the substrate and enzyme, both components modify their structure for ideal binding
What is a substrate?
The molecule on which the enzyme acts binds to the active site of an enzyme
What is kinetic energy?
The energy present in an object in motion
What is the lock and key method?
The model that shows the substrate fitting perfectly into an enzyme
Why does the rate of reaction increase in enzymes that are heated, but then reduce after a certain point?
With an increase in temperature, molecules move faster because there is more energy,
- Increases the number of collisions between molecules and enzymes
- Increases the amount of energy each molecule has so they have the required activation energy for the reaction,
- Until temp rises too much and the enzyme denatures
What is the optimum PH in the stomach and small intestine?
Stomach - PH 2
Small Intestine - PH 7-8
What is the biochemical pathway?
A specific sequence of reactions where the product of one enzyme-catalyzed reaction becomes the substrate of the next enzyme-catalyzed reaction.
Why is it beneficial to stop a biochemical pathway?
AS a product becomes available in the environment, it is wasteful and unnecessary to continue making the product through enzyme catalyzing reactions.
How are biochemical pathways inhibited?
- After the final stage of the pathway, the product goes back to the first enzyme in the biochemical pathway,
- It then binds to the enzyme’s allosteric site, the enzyme undergoes a conformational change,
- The change in shape causes a change in function, and the enzyme can no longer be used
What is allosteric inhibition?
Al-lost-eric
FMAB, Al literally lost his whole body lol
When a biochemical pathway is stopped by a final product binding to an allosteric site on the first enzyme, changing its conformation and preventing enzyme activity
What does anabolic mean? (anabolism in an enzyme)
Pathways that require an input of energy to synthesize complex molecules from simpler ones
- Making up molecules, using inputted energy
- Remember anabolic steroids build those PHAT arms
What is bioenergetics?
The study of energy flowing through living systems
What does catabolic mean? (Catabolism in an enzyme)
Pathways in which complex molecules are broken down into simpler ones
What is a coenzyme?
An organic molecule that helps the enzyme,
- They can add or remove chemical groups from the substrate
- Participate in many different reactions
What is a cofactor?
An inorganic ion that help enzymes
What is competitive inhibition?
A type of inhibition in which the inhibitor competes with the substrate molecule by binding to the active site of the enzyme,
- The active site is physically blocked and cannot be accessed by the substrate
What is feedback inhibition?
Allosteric inhibition,
- Using the product of a reaction sequence to inhibit the first enzyme by binding to it and changing the conformation of the enzyme, resulting in no function
What is metabolism?
The sum of chemical reactions that take place inside cells, including anabolism and catabolism
What is activation energy?
Necessary energy for reactions to occur
What is chemical energy?
Energy stored in chemical bonds and released when broken
What does endergonic mean?
Chemical reactions that require an input of energy
- Endothermic reactions but with energy not heat
What does enthalpy mean?
The total energy of a system
What is entropy (S)?
The measure of randomness or disorder within a system
What does exergonic mean?
Chemical reactions that release free energy
- Exothermic reactions but with energy
What is free energy?
Energy available to do work
What is heat energy?
Energy transferred from one system to another that is not work, energy of the motion of molecules or particles,
What is potential energy?
Energy that has the potential to do work,
- Stored energy
What is thermodynamics?
The study of energy and energy transfer involving physical matter
What is the transition state?
High energy in an unstable state,
- A form between the substrate and product,
- Occurs during a chemical reaction, at the peak of the energy transfer
For reactions to occur, what must happen to the potential energy?
It will decrease
What is an example of work in biology?
Biosynthesis, molecules need energy to be built up
What happens to energy change when heat is added to the system?
- Increases
- Less activation energy is required b/c the molecules are moving faster
- More energy means a high rate of reaction, so an increased number of reactants can create products.
What causes the activation energy barrier?
The transition state,
- When the enzyme-substrate complex is held together in a strained manner,
- The enzyme-substrate complex becomes unstable,
- Energy is needed to break this strain and allow the reactants to become products easily after
How do catalysts increase the rate of reaction?
Decreases the activation energy by creating another pathway for the reaction
Why do enzymes not affect the energy of the products or the reactants?
Only a new pathway is created for the reaction so that it requires less energy, meaning more reactants can create more products with equal energy,
- This works in both directions of the reaction
What are oxidation and reduction?
- Oxidation is the loss of hydrogen
- Reduction is gaining a hydrogen
OILRIG
How does an enzyme assist oxidation and reduction in NAD+?
- A substrate and the NAD+ molecule enter binding sites of an enzyme,
- The enzyme assists the substrate in transferring the hydrogen to the NAD+
- The substrate is oxidized, the NAD is reduced to NADH
What factors denature proteins?
- Temperature
- Concentration of H+ (PH)
- High concentration of polar substances
- Nonpolar substances
What are the two biological catalysts in the human body?
- Enzymes
- Ribozymes
What is an enzyme-substrate complex?
The combination of a substrate and an enzyme due to the substrate binding to the enzymes active site
What holds together the enzyme-substrate complex?
- Hydrogen bonds
- Electrical attratcion
- Or temporary covenant bonding
How is the reaction between an enzyme and a substrate written?
E + S → ES → E + P E = Enzyme S = Substrate ES = Enzyme-substrate complex P = Product
With what two methods do enzymes catalyze reactions?
- Strain
- Substrate orientation
How do enzymes “strain” substrates to catalyze reactions?
Bonds of the substrate are stretched, putting it in an unstable transitional state, which allows the bonds to be broken
How does an enzyme use substrate orientation to catalyze reactions?
Substrates are brought together so that bonds can form
How does an enzyme use chemical groups to catalyze a reaction?
The enzyme could replace or add R-groups to a substrate
What is the induced fit model?
When an enzyme changes the shape of its binding site to accommodate a substrate
What are prosthetic groups?
Non-Amino acid groups that permanently bind to their enzyme so can affect the function of the enzyme
What does it mean for an enzyme to be saturated?
The enzyme is bound to a substrate
When is the maximum rate of reaction in the presence of an enzyme?
When all enzymes are saturated
How can we measure the rate of reaction in an enzyme?
- Rate at which products are formed
- Rate at which substrates disappeared
- The reaction rate of the enzyme is taken by measuring the slope of the steepest part of the graph
What is non-competitive inhibition?
When the substrate cannot access the active site because another substrate is bound to an allosteric site, changing the shape of the enzyme and its function
Describe the process of glucose decomposition in aerobic respiration?
- Glucose is the first substrate and is broken down into the final product of pyruvate,
- The intermediate substrates between glucose (including glucose) and Pyruvate are oxidized, while NAD+ is reduced,
- An electron and hydrogen are transferred from the substrate to NAD+ with the assistance of an enzyme to create a new substrate and NADH,
- The NADH is then oxidized by transferring an electron to an O2 molecule which gets reduced to water, as it collects hydrogen floating around in the cell
- The NADH reverts back to NAD+
- The cycle restarts with the next substrate, which is the product of the last enzyme reaction.
What is chemical potential energy?
Energy stored in the bonds in molecules
What is the final electron acceptor?
The last molecule to be reduced in a sequence of enzyme reactions
What type of reaction is aerobic respiration?
- Exergonic
- Catabolic
What is the coenzyme of aerobic respiration?
NAD+
