Biology 1 Ezymes - Carbs and Digestion Flashcards
Activation energy
the minimum energy needed to start a reaction
Why are enzymes described as being biological catalysts?
they lower the activation energy and increase the rate of reaction but remain unchanged by the reaction.
Lock and Key Theory
- substrate enters the active site and fits exactly.
- Products form and no longer fit active site
- Enzyme free to take part in another reaction.
Suggests that the active site is a fixed rigid shape.
Effect of Temperature on enzyme catalysed reaction
As temp. increases there is more kinetic energy.
More successful collisions between enzyme and substrate.
More enzyme substrate complexes form.
Increased rate of reaction.
Induced Fit Model
- Substrate enters enzyme active site
- Induces change in the shape of the active site, making it complementary.
- When substrate leaves the active site returns to its original shape.
Effect of competitive inhibitors on rate of reaction
- Inhibitor is similar shape to substrate
- Binds to active site and blocks it
- No more enzyme substrate complexes form.
- Reduced rate of reaction.
Effect of substrate concentration on enzyme catalysed reaction
- Rate of reaction increases as substrate conc. increases because not all active sites are filled. Substrate conc. limiting factor.
- Graph levels off as substrate conc. continues to rise - enzyme has reached saturation point where all active sites are filled.
Enzyme is limiting factor.
Effect if Non Competitive inhibitors on rate of reaction
- Inhibitor not similar shape to substrate
- Binds away from active site
- Alters tertiary structure of enzyme
- Changes shape of active site
- Fewer enzyme substrate complexes form.
Effect of pH or temperature above optimum on rate of reaction
- Hydrogen, ionic and disulphide bonds start to break
- Tertiary structure changes shape
- Active site changes shape
- Less enzymes substrate complexes
- Lower rate of reaction
What are the two polymers of starch and their properties?
Amylose: Coils into a helix so is compact and good for storage.
Amylopectin: Branched chain, large SA for rapid hydrolysis by enzymes.
What type of bond is formed by condensation reaction between disaccharides
Glycosidic bond
Test for starch
Add iodine solution, turns from light brown to blue/black if starch present.
Which sugar is the only non reducing sugar
Sucrose
Describe the digestion of starch
Starch
Amylase (salivary)
Maltose
Pancreas
Amylase
Maltose
Maltase
Epithlial lining of small intestine
Glucose
Glucose + Glucose forms
Maltose
