M2, C4 Enzymes Flashcards
define enzyme
Enzymes are proteins used in metabolic pathways, they increase the rate of metabolic reaction by finding an alternative pathway with a lower activation energy.
what are enzymes made of
globular proteins
define anabolic
reactions of metabolism that construct molecules from smaller units
they require energy from the hydrolysis of ATP
define active site
area of an enzyme with a shape complementary to a specific substrate, allowing the enzyme to bind a substrate with specificity
define activation energy
the energy required to initiate a reaction
define catabolic
reactions of metabolism that break molecules down into smaller units
these release energy
define substrate
a substance used, or acted on, by another process or substrate
eg. a reactant in an enzyme catalysed reaction
how does an enzyme speed up a reaction
it lowers the activation energy
this means it takes less energy to initiate a reaction hence speeding the reaction up
what is the lock and key hypothesis
- an enzyme has a specific active site which is complementary to the shape of the substrate
- when the substrate is bound to the active site and enzyme-substrate complex is formed
- the substrates then react forming an enzyme-product complex
- the products are released leaving the enzyme unchanged
- temporary bonds are also formed when the R groups of the enzymes interact with the substrate which helps the reaction along
what is the induced fit hypothesis
Substrate is complementary to active site of enzyme
Substrate bind to active site of the enzyme
The shape of the active site of the enzyme changes slightly to form a tighter fit between the substrate and enzyme (the induced fit)
This forms an enzyme substrate complex
Straining of bonds in the substrate forms an enzyme product complex
Products leave active site
how would you work out metabolism
catabolic reactions + anabolic reactions
how is starch digested
starch polymers are broken down into maltose by amylase
amylase is produced by the salivary glands and pancreas and released in the saliva and pancreatic juice in the small intestine
maltose is then broken down into glucose by maltase
maltase is present in the small intestine
glucose is then absorbed into the bloodstream
how is protein digested
give an example of protease
trypsin is a protease
it catalases proteins into smaller peptides
peptides are broken into amino acids
trypsin are produced in the pancreas and released in the pancreatic juice in the small intestine
amino acids are absorbed by cells lining the digestive system and go into the bloodstream
As temperature increases how does enzyme activity change?
What’s the optimum temp in humans?
Increasing temp, increases kinetic energy in particles. The particles collide more frequently. This would mean more successful collisions between the substrate and the enzyme which increases the rate of reaction.
Optimum temperature in humans is 37
Why do enzymes denature at a too high temp?
As temperature gets high the bonds between proteins vibrate more. Bonds will then strain and break. This changes the shape of the tertiary structure of the protein.
The active site changes shape so won’t fit with the substrate so the enzyme can no longer act as a catalyst.
What does the graph look like of temperature against rate of reaction
Slow increase up to the optimum temp and then a rapid decrease
What adaptions do enzymes have which are in the cold and in the hot?
More flexible structures making them less stable
Enzymes at high temp have more bonds so are more stable and are more resistant to change
What is pH and what is its relation to hydrogen ions
It’s the measure of hydrogen ion concentration
The lower the pH, the more hydrogen ions are (more acidic)