Enzymes Flashcards
Enzymes are globular proteins that act as what?
Enzymes are globular proteins that act as catalysts
Catalysts do what without doing what themselves?
Catalysts alter the rate of a chemical reaction without undergoing permanent changes themselves
Catalysts can be reused how many times?
Catalysts can be reused repeatedly
Are therefore effective in small amounts
Enzymes do not make reactions happen - they do what?
Enzymes do not make reactions happen - they speed up reactions that already occur
Enzymes do not make reactions happen - they speed up reactions that already occur, sometimes by a factor of what?
Enzymes do not make reactions happen - they speed up reactions that already occur, sometimes by a factor of many millions
Sucrose + what —> what + what? (substrates) —> (products)
Sucrose + Water —> Glucose + Fructose (substrates) —> (products)
Sucrose + Water —> Glucose + Fructose (substrates) —> (products)
For reactions like this to take place naturally, a number of conditions must be satisfied:
The sucrose and water molecules must collide with what?
The sucrose and water molecules must collide with sufficient energy to alter the arrangement of their atoms to form:
Glucose
Fructose
The free energy of the products of a reaction (eg. glucose and fructose from sucrose) must be what?
The free energy of the products (glucose and fructose) must be less than that of the substrates (sucrose and water)
Many reactions require an initial what to start?
Many reactions require an initial amount of energy to start
What is activation energy?
Activation energy is the minimum amount of energy needed to activate the reaction in this way
There is an activation energy level, which must initially be overcome before what?
There is an activation energy level, which must initially be overcome before the reaction can proceed
Enzymes work by doing what?
Enzymes work by lowering this activation energy level
Enzymes allow reactions to take place at…. what ….than normal?
In this way, enzymes allow reactions to take place at a ….lower temperatures…. than normal
What is the human body temperature
37 C
Is the human body temperature relatively low in terms of activation energy?
Yes, this is why enzymes are important.
Without enzymes what would happen
the reactions required to sustain life wouldn’t happen.
Enzymes, being globular proteins, have a specific what?
Enzymes, being globular proteins, have a specific 3-D shape
Enzymes, being globular proteins, have a specific 3-D shape that is the result of their what?
Enzymes, being globular proteins, have a specific 3-D shape that is the result of their sequence of amino acids (primary protein structure)
A specific region of the enzyme is what?
The Active Site
The active site is made up of a relatively small number of what?
The active site is made up of a relatively small number of amino acids
The active site forms a small what within the much larger enzyme molecule?
The active site forms a small depression within the much larger enzyme molecule
The molecule on which the enzymes does what is called the substrate?
The molecule on which the enzymes acts is called the substrate
This substrate fits nearly into this depression and forms what?
Forms an enzyme-substrate complex
The substrate molecule is held within the active site by what?
The substrate molecule is held within the active site by bonds
The substrate molecule is held within the active site by bonds that do what?
The substrate molecule is held within the active site by bonds that temporarily form between:
- Certain amino acids of the active site
- Groups on the substrate molecule
What does the induced fit model of enzyme action propose?
The induced fit model of enzyme action proposes that the active site forms as the:
Enzyme +
Substrate
Interact
The proximity of the substrate (a change in what) leads to what?
The proximity of the substrate (a change in the environment of the enzyme) leads to a change in the enzyme
The proximity of the substrate (a change in the environment of the enzyme) leads to a change in the enzyme that forms what?
The proximity of the substrate (a change in the environment of the enzyme) leads to a change in the enzyme that forms the functional active site
The proximity of the substrate (a change in the environment of the enzyme) leads to a change in the enzyme that forms the functional active site.
In other words, the enzyme is what?
The enzyme is flexible
The enzyme is flexible and can mould itself around what in the way that a glove moulds itself to the shape of the hand?
In other words, the enzyme is flexible and can mould itself around the substrate in the way that a glove moulds itself to the shape of the hand
As it changes its shape, the enzyme does what to the substrate molecule?
As it changes its shape, the enzyme puts a strain on the substrate molecule
This strain does what?
This strain distorts:
- A particular bond
OR
- Bonds
In teh substrate
This strain distorts a particular bond or bonds in the substrate and consequently does what?
This strain:
- Distorts a particular bond or bonds in the substrate
- Consequently lowers the activation energy needed to break the bond
Any change in an enzyme’s environment is likely to do what?
Any change in an enzyme’s environment is likely to change its shape
The very act of doing what is a change in its environment?
The very act of colliding with its substrate is a change in its environment
The very act of colliding with its substrate is a change in its environment and so what?
The very act of colliding with its substrate is a change in its environment and so its shape changes - induced fit
One earlier model of enzyme action proposed that enzymes work in the same as what?
One earlier model of enzyme action proposed that enzymes work in the same as a key operates a lock
Each key has a partiuclar shape and fits a particular lock.
One limitation of the Lock and Key model is that the enzyme, like a lock, is considered to be what?
One limitation of this model is that the enzyme, like a lock, is considered to be a rigid structure
One limitation of this model is that the enzyme, like a lock, is considered to be a rigid structure.
However, scientists had observed that other molecules could do what?
Scientists had observed that other molecules could bind to enzymes at sites other than the active site
Scientists had observed that other molecules could bind to enzymes at sites other than the active site.
In doing so, they altered what?
In doing so, they altered the activity of the enzyme
The induced fit model is therefore a what version of the lock and key model?
The induced fit model is therefore a modified version of the lock and key model
which better reflects the observations of scientists regarding the flexibility of the enzyme structure.