1.4 - Biological reactions are regulated by enzymes Flashcards
What is metabolism?
a series of enzyme-controlled reactions in the body
What are the two main types of reaction?
Anabolic reaction
Catabolic reaction
What does an anabolic reaction do? What does a catabolic reaction do?
Anabolic: protein synthesis where amino acids are built up into more complex polypeptides
Catabolic: digestion of proteins, where complex polypeptides are broken down into simple amino acids
what are enzymes?
all enzymes are tertiary globular proteins where the protein chain is folded back on itself into a spherical or globular shape
what can enzymes be described by and what does this mean?
can be described as biological catalysts as they speed up the rate of metabolic reaction, but they are not changed by the reaction and do not get used up.
where are all enzymes made?
inside the cell
what are the sites of enzyme action?
extracellular
intracellular
What are the two different models for enzyme reaction?
- lock and key theory
- induced fit hypothesis
What does the lock and key model suggest?
that the substrate has a complementary shape to the enzymes active site and therefore that many enzymes only catalyse one substrate
What does the induced fit hypothesis suggest?
active site of enzyme changes shape slightly to accommodate the substrate to form an enzyme substrate complex, the reverts to it’s original active site shape
what is the example for the induced fit hypothesis? And how does it work?
the enzyme lysozyme
it is an antibacterial enzyme in human saliva, tears and mucus
it attaches to the wall of bacteria and breaks glycosidic bonds
what does itt mean if an enzyme has disulphide bonds present?
it is likely to withstand quite high temperatures
Enzymes are biological catalysts. How do they bring about the effect of speeding up a reaction?
The substrates fit into the active site of the enzyme and therefore lowers the activation energy
What are the four factors affecting enzyme rate of reaction?
- substrate concentration
- temperature
- pH
- enzyme concentration
- presence of inhibitors
how does substrate concentration effect the enzyme rate of reaction?
when the substrate increases in an enzyme-controlled reaction, there is a greater chance of a successful collision between the substrate and the enzyme, resulting in more enzyme-substrate complexes forming.