Enzymes Flashcards
What are enzymes?
Enzymes are biological catalysts made of protein
what is a catalyst?
A catalyst is a substance that speeds up reactions without
themselves being used up in the reaction
What does an enzyme have in the words that make them an enzyme?
Most enzymes have the suffix ‘ase’ at the end.
but there are some that don’t eg pepsin, rennin, and trypsin,
Define metabolism
Metabolism is the sun of all chemical reactions in the body of an organism
How is the function of a protein decided?
The function of a protein is decided by the sequence
of amino acids but also by the way the protein folds
What type of protein are most enzymes?
Globular proteins
How do enzymes work?
Enzymes have a specific shape that means that it will fit neatly and react only with a substance whose shape matches the
enzyme.
What is a substrate?
Substrate is the substance that an enzyme reacts with.
What is a product?
Product is the substance the enzyme forms.
What are the two categories of enzyme?
Catabolic and Anabolic enzymes
What are catabolic enzymes?
A catabolic enzyme breaks down a substance into smaller
parts.
Amylase (produced in the mouth & pancreas) converts Starch
into Maltose.
Pepsin in the stomach breaks down proteins into peptides
Catalase breaks don hydrogen peroxide in water and oxygen
what are anabolic enzymes?
anabolic enzymes use anabolism which is where simple chemicals are changed into
complex chemicals using enzymes & energy.
DNA polymerase forms and repairs DNA. DNA polymerase is anabolic as it converts simpler molecules into more complex molecules.
what is formed when the correct enzyme and substrate come together?
When enzymes and their substrates meet and come together they form an Enzyme/Substrate complex
what is the induced fit model?
When the substrate enters the active site it causes it to
change shape slightly.
The enzyme then fits more precisely around the substrate
this is known as the Induced Fit model of enzyme action.
are enzyme reactions reversible or irreversible?
Enzyme Reactions are reversible
What are inhibitors?
Inhibitors attach to enzymes and destroy their shape
When this happens the enzymes are said to be denatured
eg Cyanide denatures an enzyme involved in respiration
Give an example of a beneficial enzyme inhibitor
Insecticides affect enzymes in insects causing their death
Drugs can affect enzymes involved in pain causing the pain
to stop
Antibiotics can affect enzymes in bacteria causing the
bacteria to die
What factors influence enzyme activity?
Factors that affect enzymes include-
Temperature
pH
Substrate concentration
Enzyme concentration
How does temperature affect enzyme activity?
At very low temperatures ice forms, liquids become solids
and enzymes can’t work.
As temperature increases molecules gain kinetic energy which increases the enzymes and the substrates chances of a successful collision. Rate of reaction increases
What is the optimum temperature of plant enzymes and animal enzymes?
Human enzymes work best at body temperature (37°C)
Plant Enzymes work best at 20-30 °C
This is the enzymes optimum temperature (the temp it works best at)
What is enzyme denaturation?
When the shape is fully lost the enzyme is said to be
denatured this is usually a permanent condition.
What causes an enzyme to become denatured?
Enzymes can be denatured by:
-Heating to very high temperatures.
- Very high or low pHs
- Radiation
How does increased substrate concentration affect rate of reaction?
If there are a lot of substarte molecules it increases the chnaces of there being a sucessul collisions between the substarte and the enzymes so the rate of reaction increases
How does Ph affect rate of reaction for enzymes?
Most enzymes work at ph 6-8. Outisde of this the enzymes become denatured. Their optimum ph is usually 7
