Enzymes Flashcards
What happens in a dipeptide formation
A condensation reaction
H20 is made
A peptide bond is formed
Molecule made is called a dipeptide
Describe hydrolysis
H20 is used
Peptide bond is broken
Amino acids are formed from the dipeptide
Define primary structure
The specific sequence of amino acids in a polypeptide chain
Define secondary structure
The cooling and pleating of parts of the polypeptide chain to form an alpha helix or a beta pleated sheet
Held together by hydrogen bonds
Define tertiary structure
When the secondary alpha helix and beta pleats fold to five a complex 3D specific shape
Describe the bonds that hold the tertiary structure in place
Hydrogen bonds between polar groups
Disulphides bonds are covalent bonds formed between sulphurs in the r group of the amino acid cytesine
Ionic bonds between r groups of amino acids
Hydrophobic interactions between non polar r groups
Hydrophilic r groups on the outside of molecule in contact with water
What is the job of a catalyst
To speed up the rate of reaction
What type of molecule is an enzyme
A protein
What enzyme does protein synthesis use
Peptidyl transferase
Name a product which enzymes are used in
Biological washing powders
Give an advantage of a biological washing powder
Can sometimes work at low temperatures which can save energy and the environment
Some only work well at 40°
What type of protein are enzymes
Globular
Describe globular proteins
Have a specific 3D shape
Soluble in water
Have an active site
Ball like structure
Name the enzyme used in photosynthesis
Rubisco
Name the substrate that
Amylase creates from starch
Maltase creates from maltose
Maltose
Alpha glucose
Give another name for :
A hydrolysis reaction
A condensation reaction
Catabolic
Anabolic
Where do reactions occur in:
Extracellular enzymes
Intercellular proteins
Outside a cell
Inside a cell
Name the product and the bond broken for:
Proteins
Fats
Polysaccharides
Amino acids - peptide bond
Glycerol and fatty acids- Ester bonds
Disaccharides- glycosidic
What are extracellular enzymes
Enzymes that catalyse reactions outside of the cell
What enzyme hydrolyses proteins into amino acids in the stomach
Pepsin
What is a phagosome like
A vesicle
They engulf and digest pathogens
What is the function of catalase
Breaks down hydrogen peroxide into water and oxygen
Define activation energy
The minimum energy needed to start a chemical reaction
How do enzymes lower activation energy
Forming enzyme-substrate complexes
Which speeds up metabolic reactions
Describe lock and key theory
The shape of the active site of the enzyme is always complimentary to the shape of the substrate
Like a lock it is complimentary to its key
Shape of active site does not change
Describe induced fit model
The model is based on more evidence and suggests the active site of the enzyme is not fully complimentary to the substrate
But as the substrate collided with the active site the enzyme active site changes shape
Causing the active site to fit more closely with the substrate
Puts strain on bonds in the substrate meaning they break more easily
Describe the process of induced fit model
The active site is not fully complimentary shape to the shape of substrate. But the active site has charged amino acids r groups which are attracted to the substrate.
Substrate collides randomly with active site
Enzyme changed shape and active site becomes fully complimentary
This puts strain on the bonds meaning they break more easily
Produces enzyme product complexes
How do low temperatures effect enzyme activity
Low temps have less kinetic energy
Decreasing random collisions of substrate and active site
Less ESC firmed per second
Slower rate of reaction
Enzyme is not denatured
How do high temperatures effect enzyme action which are still BELOW optimum
Higher temperatures have more kinetic energy
More random collisions of active site and substrate per second
More ESC
Increased rate of reaction
What does Q10=3 mean
For every 10°c rise in temp - the rate of reaction trebled (x3 fast)
What is the optimum temp of enzymes in the human body
40°c
Describe what happens to enzymes when temperature increases
The enzyme molecules have increased KE
The enzyme molecule vibrates more
Too much KE causes the hydrogen and ionic bonds to break
The 3D shape changes
Active site is altered
No longer complimentary
Less ESC
What type of ions are present in:
Acids
Alkalis
Acids-H+ ions
Alkalis-OH-
How do ions affect the active site
Charged ions attract or repel from charges in the protein structure
Changes the charge of active site
Bonds break
3D structure changes (inc active site)
Fewer ESC
What happens in denaturation due to pH
Too many bonds break beyond the point of returning to original shape
What is renaturation
Where small changes in the pH away from optimum temperature are followed by a return in pH to its optimum
Fill in the blanks:
\_\_ group interactions are disrupted \_\_\_\_\_\_ and \_\_\_\_\_\_ bonds break The tertiary structure and \_\_\_\_ \_\_\_\_\_\_\_\_\_ of enzyme changes Change shape of \_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_ Prevents substrate from bonding
R
Hydrogen and ionic
3D shape
Active site
What are extracellular enzymes
Enzymes that catalyse reactions outside of the cell
What enzyme hydrolyses proteins into amino acids in the stomach
Pepsin
What is a phagosome like
A vesicle
They engulf and digest pathogens
What is the function of catalase
Breaks down hydrogen peroxide into water and oxygen
Define activation energy
The minimum energy needed to start a chemical reaction
How do enzymes lower activation energy
Forming enzyme-substrate complexes
Which speeds up metabolic reactions
Describe lock and key theory
The shape of the active site of the enzyme is always complimentary to the shape of the substrate
Like a lock it is complimentary to its key
Shape of active site does not change
Describe induced fit model
The model is based on more evidence and suggests the active site of the enzyme is not fully complimentary to the substrate
But as the substrate collided with the active site the enzyme active site changes shape
Causing the active site to fit more closely with the substrate
Puts strain on bonds in the substrate meaning they break more easily
Describe the process of induced fit model
The active site is not fully complimentary shape to the shape of substrate. But the active site has charged amino acids r groups which are attracted to the substrate.
Substrate collides randomly with active site
Enzyme changed shape and active site becomes fully complimentary
This puts strain on the bonds meaning they break more easily
Produces enzyme product complexes
How do low temperatures effect enzyme activity
Low temps have less kinetic energy
Decreasing random collisions of substrate and active site
Less ESC firmed per second
Slower rate of reaction
Enzyme is not denatured
How do high temperatures effect enzyme action which are still BELOW optimum
Higher temperatures have more kinetic energy
More random collisions of active site and substrate per second
More ESC
Increased rate of reaction
What does Q10=3 mean
For every 10°c rise in temp - the rate of reaction trebled (x3 fast)
What is the optimum temp of enzymes in the human body
40°c
Describe what happens to enzymes when temperature increases above optimum
The enzyme molecules have increased KE
The enzyme molecule vibrates more
Too much KE causes the hydrogen and ionic bonds to break
The 3D shape changes
Active site is altered
No longer complimentary
Less ESC
What type of ions are present in:
Acids
Alkalis
Acids-H+ ions
Alkalis-OH-
How do ions affect the active site
Charged ions attract or repel from charges in the protein structure
Changes the charge of active site
Bonds break
3D structure changes (inc active site)
Fewer ESC
What happens in denaturation due to pH
Too many bonds break beyond the point of returning to original shape
What is renaturation
Where small changes in the pH away from optimum temperature are followed by a return in pH to its optimum
Fill in the blanks:
\_\_ group interactions are disrupted \_\_\_\_\_\_ and \_\_\_\_\_\_ bonds break The tertiary structure and \_\_\_\_ \_\_\_\_\_\_\_\_\_ of enzyme changes Change shape of \_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_ Prevents substrate from bonding
R
Hydrogen and ionic
3D shape
Active site
When will the reaction be the quickest
When the enzyme and substrate are mixed together
Describe the effect of increasing substrate concentration
More enzyme substrate complex is the forms therefore the reaction increases
Eventually all active sites will be occupied and therefore the reaction will reach v max
Enzyme concentration is the limiting factor
Define in inhibitor
A substance that slows down the rate of an enzyme catalysed reaction by affecting the enzyme in some way
Describe competitive inhibitors
Have a similar shape to the substrate that are complimentary to the active site they fit into the active site forming an enzyme inhibitor complex which blocks the substrate from binding
this means there are fewer active sites available and fewer enzyme substrate complex is which reduces the rate of reaction
Describe a non-competitive inhibitor
Binds away from an active site at an allosteric site which is a different shape to the active site
Causing changes to the Tertiary structure in 3-D shape of the enzyme
the active site shape alters which are no longer complimentary to the substrate this can sometimes be permanent and reduces the rate of reaction
Give an example of a competitive inhibitor
Statins
which is used to synthesise cholesterol
How does penicillin work as an inhibitor in medicine
It penicillin helps form the cell walls of bacteria
The cell wall protein not constructed so results in bursting of the bacteria
How does ethanol work as a competitive inhibitor (in antifreeze)/
Higher the ethanol conc the greater chance of ethanol binding with active site
Less chance of ethylene glycol binding to active site and is broken down
Less production of oxalis acid (toxic)
Give two examples of non competitive inhibitors
Organophosphates> found in insecticides
Inhibits enzyme used in nerve impulse conduction
Proton pumps are used to treat long term indigestion
What are cofactors
A non-protein helper that must be present for the enzyme reaction to take place at the appropriate rate
Describe coenzymes
Often made from vitamins
they are small organic non-protein molecules that bind loosely with the active site
they are charged and are recycled so can be used again
Describe inorganic ions which are used as cofactors
Charged particles which can affect the charge distribution and sometimes the shape of the active site
the ions bind to the enzyme making enzyme substrate complexes form more easily
Maltase and amylase both require what ion
Chloride ions
describe prosthetic groups
Permanent parts of an enzyme molecule that helps with the 3-D shape
They are sometimes required by certain enzymes in order to function
What is a inactive precursor enzyme
Enzymes which are produced in an inactive form
They often need to undergo a change in shape - once this happens the enzyme becomes activated (could be achieved by adding a cofactors or another enzyme/ or through a change in conditions such as pH or temp)
