Enzymes and Metabolism Flashcards
Unit 2: Biomolecules
Define Catalysts
Substances that speeds up a chemical reaction but is unchanged by the reaction
Pros of catalysts
They can be used over and over
Less of them required relative to the reactants
Define enzymes
They are biological catalysts made by cells that convert substrates into products
What would happen if there were no enzymes in life
The life’s processes would be very slow
Define Metabolism
Complex network of interdependent and interacting chemical reactions occurring within cells/living organisms
What happends during metabolism
Transform one type of molecule into another in a series of small steps
They allow cells to make energy, build and deassemble
What causes metabolism?
Most are by an enzyme
What does each enzyme catalyze?
They catalyze a specific reaction or a specific group of reactions
What are non-biological catalysts
They are not specific like enzymes
What does specificity of enzymes allow?
They allow organisms to control metabolism
What is controlling the rate of reaction?
Organism making more, making less or temporarily stopping the reaction.
Example of a metabolic cycle?
The calvin cycle, a part of photosynthesis
Example of a metabolic chain?
Glycolysis, a part of respiration
Define anabolic reactions
Building up of complex molecules from simpler ones
How does anabolic reactions occur?
They occur via condensation reactions (water being produced as a result)
What is required for an anabolic reactions to occur?
Energy
Example of an anabolic reactions
The production of glucose by photosynthesis and then in to the polymers starch, cellulose
Define catabolic reactions
Breaking down of complex molecules into simpler ones
How does catabolic reactions occur?
They occur via hydrolysis reactions (Water is consumed)
What happends to the energy during catabolic reactions
Energy is released
Example of a catabolic reactions?
Cell respiration
Define substrate
Substance that enzymes convert into products
Define active site
A special region on surface of enyme that binds to the substrate
What is required for active site reaction to take place?
Binding is required
How do substrate and active site bind?
When a substrate is near the enzyme the surface properties attract the substrate
What happes when the product detach from the active site?
The active site returns to its original state
What happens when a second substrate exists the active site?
It binds to another part of the active site and again, changes in both allows bonding
What is needed for an enzymatic reaction to occur?
The substrate and enzyme must physically collide in the correct orientation to facilitate binding to the active site
How can the rate of enzyme catalysis increased?
By increasing the molecular motion of the particles (thermal energy)
Increasing the concentration of particles
What makes the enzymatic reaction possible?
They are possible in aqueous solutions where molecucels are in a constant motion (brownian motion)
How to motions of substrates and enzymes differ?
Substrate are usually smaller so they mvoe more and faster than enzymes.
But some substrates are large and do not much
Sometimes an enzyme is at a particular site and is fixed to a position
How can enzyme structures be modified?
They can be modified by external factors such as high temperatures and extreme pH
What do external factors that modify the enzyme disrupt?
They can disrupt the chemical bonds which are necessary to maintain the shape and chemical properties of the enzyme
What is denaturation?
What the changes are too great it can’t be reversed
What can prevent catalysis after binding?
Any changes to the structure of the active site
What can also happen by obstructing the active site or altering its shape?
Certain molecules (inhibitors) reducing enzyme-substrate interactions
Define independent variable (IV)
The factor you deliberately change to see what the effect is, usually just one
Define control variables (constants)
The factors kept the same/constant to ensurea fair test.
Define dependent variable
The results of the experiment
Define reaction rates
speed at which substances are converted to products
Equation to calculate the reaction rate
Reaction rate = Quantity of substance/time
What is logarithmic scales
Each interval is 10x the previous one
When is logarithmic scales useful?
Useful when data has large ranges and is difficult to plot the small numbers/see differences
Useful to test if a relationship is truly exponential. Using a log scale a truly exponential scale will be linear
Define activation energy
The initial rise in energy seen in the graph in the energy input needed before the reaction will occur
What happens before being converted to product?
Substrates pass through a transition state
What is the subsequent drop in energy?
It is the energy released by the reaction
Define extracellular enzyme
Made by ribosome on the rER but released from cells and work outside (exoenzymes)
Example of an extracellular enzyme
Breakdown of macromolecules during digestion
Define intracellular enzymes
Made by free ribosomes and used inside the cell (endoenzyme)
Example of an intracellular enzymes
Enzymes are in the cytoplasm needed for glycolysis
What happens in generation of heat energy by the reactions of metabolism?
The products contain less energy than the reactants due energy loss being converted to heat
What happens when the temperatures drop?
Muscles contract, generating heat
How is heat generated without making ATP?
Brown fat metabolizes when its cold, the fat is then broken down
Define pathway
Linked series of chemical reactions occurring within a cell
What’s a linear pathway?
Called a chain
What’s a cyclical pathway?
Intermediate products are the reactants for the step in the reaction
Example of an allosteric site
A second active site that some enzymes have where a different specific substanes can bind and unbind, this binding causes interactions that lead to a shape changes in the enzyme
What is the allosteric inhibitor?
Prevents the original substrate from binding (by chaing enzyme shape)
Catalysis is prevented
The inhibitor in this situation does not compete with the original substrate
What is non-competitive inhibitors
Inhibitors that does not compete with the original substate, allosteric inhibitor
What is an allosteric activator?
They bind to the allosteric site but cause activation of the reaction
What happens when allosteric inhibitor is bind to an active site?
Catalysis is prevented, changing the enzyme’s shape
Why are allosteric inhibitors caleld non-competitve inhibitors?
The inhibitors do not compete with the original substrate as it has a spot in the opposite side of the active site to connect.
What is allosteric activator?
Bind to the allosteric site but cause activation of the reaction. Causes the reaction to occur by altering the shape of the active site
What is a competitive inhabitor
They bind to the active site/ They have similar structure to the substrate, but no reaction will occur when bound.
What controls many metabolic pathways?
They are controlled by feedback inhibition
What is a mechanism based inhibition?
Some irreversible inhibitors that target specific substrates, but they remain bonded to the active site
