Enzymes Flashcards
What is metabolism?
-describes all the chemical reactions occuring constantly in the cell that maintain homeostasis`
What are metabolic pathways?
- the orderly step-wise series of chemical reactions from the initial reactants to the final products
- one reaction leads to the next
- controlled by enzymes; each step requires a specific enzyme
Why do metabolic pathways exist?
- it’s impossible to have a single reaction that could produce complex molecules from simple reactants
- one pathway can lead to several others(intermediate products of one pathway can be starting reactant for another pathway)
- having more than one step means that there are more places where the overall reaction can be controlled
What is an enzyme?
- a globular protein that acts as a catalyst of chemical reactions
- sites of chemical reactions but aren’t used up in the reaction or permanently changed by the reaction
- can hold reactant molecules together long enough for them to react
- highly specific; each enzyme speeds up only one reaction
- enzymes names usually end with the suffix “ase” or “sin”
What is the equation for an enzyme-catalyzed reaction?
E + S –> ES –> E + P
“E” = enzyme
“S” = the reactant(s) in an enzyme’s reaction
“ES” = enzyme substrate complex(chemical reaction occurs)
“P” = product
What is the active site?
- a region on the surface of an enzyme to which substrates bind and which catalysts a chemical reaction involving the substrates
- allows related molecules to bind but possibly preventing undesirable substrates from binding
- the shape of the active site only corresponds to the shape of the substrate when the substrate binds
Describe the structure of an enzyme
- a protein part called an apoenzyme that gives it its specificity(i.e. exactly what reaction it will catalyze)
- a non-protein group called a coenzyme which may help out the reaction by accepting or donating atoms(eg H)
What is coenzyme?
- large non-protein molecules
- many are vitamins(nicotonic acid, vitamin B2, vitamin H, vitamin B1)
- may help reaction by participating in reaction by accepting or donating atoms to the reaction
What is apoenzyme?
- protein part of enzyme
- gives specificity to particular reaction
What are the factors that change the shape of the enzyme?
- pH
- temperature
- concentration
What happens when pH is too low or high?And what is the most ideal pH for enzyme
- pH 6-8(except for stomach acid)
- if the pH is too low or high, the enzyme denatures(the structure of the enzyme changes in which it can no longer carry out its function
What happens when the temperature changes?
- decreasing temperature will slow rate of reaction; the lower the temperature, the lower the rate of reaction
- low temperatures don’t normally denature the enzyme
- increasing the temperature will at first increase the rate of reaction, but when temperature gets too high(above 45 degrees)the enzyme will denature
What happens when the concentration of substrates change?
- if the concentration of substrate increases, the amount of product increases as well; however after a certain concentration the rate won’t increase anymore as all the enzymes are already being used
- if the concentration of substrate decreases the rate of product formation will decrease as well
What happens when the concentration of enzyme change?
- limits the overall rate of reaction
- if concentration of enzyme increases, rate of product formation increases
- if concentration of enzyme decreases, the rate of product formation decreases as well
How do enzymes work?
When substrates bind to the active site, the enzyme changes shape slightly to bind the substrate more tightly. This is due to changes in the R groups of amino acids as they interact with the substrate. And when the product is produced, the enzyme changes back to its original shape.
