Enzymes Flashcards
What is an anabolic reaction
Chemical reactions required for growth
Building up
What is a catabolic reaction
Breaking down
Enzymes can only increase the rate of reaction up to a certain point, what is this called?
Vmax
What energy is needed to be supplied for start of most reactions
Activation energy
How do enzymes help molecules
Help them collide more successfully so reduce activation energy needed
Deacribe the lock and key hypothesis
Area within tertiary structure of enzyme that has a a shape that is complimentary to a specific substrate molecule
‘Lock and key’
When substrate is bound to active site an enzyme substrate complex is formed. Substrate reacts and forms a enzyme-product complex.
Product is then released,leaving enzyme unchanged
Substrate held in a way atom groups interact
R group on active site interact with substrate too
Describe the induced fit model
Active site of an enzyme changes shape as substrate enters. Initial reaction between enzyme and substrate is weak, so change enzyme tertiary structure that strengthen binding on substrate molecule
Weakens a particular Bon in substrate so lower activation energy needed
What do all reaction in cells need
Substrates
Raw materials need to be supplied to cells, what can supply these materials
In our diet
Proteins
Polysaccharides
Enzymes break down large nutrient molecules into smaller ones
What are extra ellipse enzymes
Break down large nutrient molecules into smaller ones by digestion
They work outside of the cell that made them
What relies on extra cellular enzymes to make use of polymers for nutrition
Single and multicellular organisms
Describe digestion of starch
Begins in mouth to small intestines
Starch polymers are broken down partially into maltose by analyse (produce by pancreatic juice/saliva InMouth)
Maltose is then broken into glucose
Enzyme maltase used.
Glucose absorbed by cell lining to digestive system and absorbed into blood stream
Describe digestion of proteins
Trypsin is a protease that catalyses digestion of protein into smaller peptides, which are then broken down into amino acids
Trypsin is produced in prancreas in small intestines where acts as proteins
Amino acids made are absorbed by blood stream of cell lining of digest for system
How does temperature affect enzymes
Increase kinetic energy as particles move faster
What is temperature coefficient
Measure of how much the rate of reaction increases with a 10c rise in temp.
What happens if temperate is too hot in enzyme
Bonds become strained and break, changing tertiary structure
Denature for enzyme
What is an optimum temperature of an enzyme?
Enzymes highest activity rate
How are enzymes in the metabolic activities, for example, adapted to the cold?
More flexible Structures e.g. At active site- makes less stable than enzymes at higher temperatures
How do organisms that are adapted to the cold, denature?
When there are small subtle temperature changes
What’s a thermophile
Organism that’s adapted to live in high temperatures like hot springs
How do thermophile a survive in high temperatures
More bonds so more stable
E.g more h and sulfar bonds in tertiary structure
What does a change in pH often refer to in enzymes
Change in hydrogen ion concentration
What is the difference between low and high pH referring to hydrogen ions
Low PH- more hydrogen ions present
High pH- fewer hydrogen ions
What is the optimum pH
Had the right shape for active site at a specific hydrogen ion concentration
What is renaturation
When the next me becomes too acidic or alkalin, altering the structure
But then returns back to the optimum pH and the protein carries on normal shape and catalysing reactions
What happens when the pH changes more significantly?
Structure of enzyme irreversible
Substrate can’t join active site
Therefore denatured
Reduces rate of reaction
What do hydrogen ions react with (pH)
Polar and charged r groups
When hydrogens interact with polar and charged R groups, what do they change?
The concentration of hydrogen ions, changing the degree of reaction
The more hydrogen ions present, this means less….interact with eachother
R groups
From the result of more hydrogen bonds therefore less R groups interacting with eachother, what does this lead too?
Leads to bonds breaking and shape of enzymes changing
From the shape changing due to lots of hydrogen ions, when is it more like to be reversible
When there is fewer hydrogen ions present (high pH)
Site of action for saliva
PH?
Mouth
7- neutral
What enzyme is in salvia and salvias function
Amylase
Starch I maltose
Where’s the site of action or gastric juice
pH level?
Stomach
1-2 acidic
Enzyme in gastric juice
Function of gastric juice
Pepsin
Proteins to polypeptides
Where’s the site of action for pancreatic juice
pH level
Small intestine
8 slightly alkaline
What enzyme is involved in pancreatic juice
What’s its function
Trypsin -proteins to polypeptides
Maltase- maltose to glucose
What happens when the concentration of a substrate is increased?
Number of molecules in particular area increases, therefore more number of substrate particles leading to higher collision rate with active site to form a enzyme-substrate complex.
What happens when the enzyme concentration is increased?
More available active sites in an area, leading faster reactions of enzyme-substrate complexes
Where does the rate of reaction increase up to
The max known as V max
What is v max
Where all active sites are occupied by a substrate molecule and no more can be made.
What is a way you could increase reaction when it has reached V max
Add more enzymes or increase temp
If
Concentration of enzymes increased =more active sites, reaching a higher V max
By controlling the activity of enzymes at crucial points in the reaction pathway allows it too…
Regulates the rate and quantity of product formation.
What can activate enzymes
What can deactivate them
Cofactors
Inhibitors
What are inhibitors
Molecules that prevent enzymes from carrying out function as catalysts
What are the two types of inhibitors
Competitive
Non competitive
How does a competitive inhibitor work
A molecule that has a similar shape to active site so blocks the substrate from entering it.
Enzyme is now inhibited as can’t carry out catalyst functions
What happens when a substrate and a competitive inhibitor is involved in a solution
Both compete to bind to active site of enzyme, therefore reducing the amount of substrate molecules binding to active site; slowing rate of reaction.
Describe competitive inhibitors
Compete for active site
Only temporary so reversible
Example of a competitive Inhibitor that ISNT reverisble
Aspirin
How does a competitive inhibitor affect the rate of reaction?
Reduces rate of reaction.
But doesn’t change v max of enzyme it inhibits
If substrate concentration is increased enough there will be more substrate than inhibitor so original v max can still be reached
Examples of competitive inhibitors
Statins
Aspirin
What are statins
Synthesise cholesterol
Prescribed to reduce blood cholesterol concentration
Describe aspirin
Inhibits active site of COX enzyme
Prevents synthesis of prostaglandins and thromboxane- chemical that reduces pain and fever
How do non competitive inhibitors work
Binds to active site at anywhere but active site. (Allosteric site)
The binding causes tertiary structure of enzyme to change, altering shape
Substrate can’t bind anymore
Affect of increasing concentration of enzyme or substrate to overcome non competitive inhibitors
No effect of
Over coming inhibitor
What happens if you increase amount of non competitive inhibitors
Decreases rate of reaction as more active sites aren’t available
Example of non competitive inhibitors
Organophosphates- insecticides- inhibits enzyme for nerve transmission
Proton pump inhibitors
Used to treat long term indigestion
Block enzyme system that secretes hydrogen ions in stomach.
What does end product inhibition mean
Term used for enzyme inhibition Occurs when product of a reaction acts as an inhibitor to the enzyme that produce it. - serves as negative feed back control mechanism
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