4.1 Enzyme Action Flashcards
What are enzymes?
Biological catalysts.
They are globular proteins that interact with substrate molecules causing them to react at much faster rates
What reactions are enzymes involved in?
Anabolic (building up) reactions for growth
Catabolic (breaking down) reactions e.g. for energy to be released from glucose stores
What does ‘specificity of the enzyme mean’?
Each enzyme catalyses one biochemical reaction
Describe the lack and key hypothesis
The substrate fits into the enzymes complementary active site, an area within the tertiary structure, the same way the right key will fit into a lock
When the substrate is bound to the active site and enzyme-substrate complex is formed. The substrate then reacts and products are formed and released
describe the induced fit hypothesis
- evidence has suggested that the active site of the enzymes actually change shape slightly as the substrate enters
- the initial enzyme - substrate interaction is relatively weak but this induces change in the enzyme’s tertiary structure which strengthens binding, putting strain on substrate molecule
What are intracellular enzymes?
Enzymes that act within cells
e.g. catalyse ensures hydrogen peroxide, a toxin by product of metabolism, is broken down
What are extracellular enzymes?
They work outside the cell that made them
Describe the digestion of starch
- the digestion of starch begins in the mouth and continues in the small intestine
Starch is digested n two steps (involving two different enzymes):
1) starch polymers are partially broken down into maltose by the enzyme amylase. Amylase is produced by salivary glands and the pancreas
2) maltose is the broken down into glucose, by the enzyme maltase. Maltase is present in the small intestine
Glucose is small enough to be absorbed by the cells lining the digestive system and therefore can be absorbed into blood stream
Describe digestion of proteins
Trypsin (a protease) catalyses the digestion of proteins into smaller peptides and then into amino acids
