Chapter 4 - Enzymes Flashcards
What is the purpose of enzymes?
To provide a biological catalyst, and to speed up reactions within the body.
What are enzymes?
- Globular Proteins
- Biological Catalyst
What is the Vmax?
The maximum initial velocity of the rate of the enzyme-catalysed reaction, under constant temperature, pH, and pressure.
How do Enzymes catalyse reactions?
Enzymes help molecules collide successfully, therefore lowering the activation energy necessary for the reaction to occur.
What is Lock and Key Hypothesis?
The theory that the enzyme and the substrate are directly complimentary to one another, like a lock and a key.
What is formed when the enzyme and the substrate bond?
Enzyme-Substrate Complex.
True or False - The enzyme is included as one of the reactants in the reaction.
False - after catalysing the reaction, the products are released and the enzyme is left unchanged, therefore meaning it is not included as a reactant.
What is the Induced Fit Hypothesis?
The theory that the enzyme and the substrate are only partially complimentary, but the kinetic energy of the substrate colliding with the enzyme causes change in its tertiary structure.
How does the induced fit theory lower activation energy?
The weak interactions between the enzyme and the substrate change the tertiary structure of the enzyme, making the bonds stronger, which puts strain on the substrate, therefore reducing the activation energy for the reaction.
What is an Intracellular Enzyme?
An enzyme that acts within a cell.
What is an example of an intracellular enzyme?
Catalase - ensures breakdown of toxic Hydrogen Peroxide.
What is an Extracellular Enzyme?
An enzyme that works outside of the cell that created it.
What are examples of an extracellular enzyme?
Amylase + Trypsin - Used for digestion in the breakdown of big nutrient and vitamin molecules so that they can become useful to the body.
What is the first step of starch digestion?
Amylase (salivary gland) breaks down starch into maltose, a dissacharide.
What is the second step of starch digestion?
Maltase (small intestine) breaks down Maltose into Glucose, a monosaccharide; This is useful to the body, as glucose is small enough to be absorbed through small intestine lining.
How are proteins digested?
- Digested by Proteases, e.g. Trypsin, which catalyses the digestion of proteins into smaller peptides.
- Other proteases break these peptides down further into amino acids; These are small enough to be absorbed into the bloodstream.
What are some of the factors affecting enzyme activity?
- Temperature
- pH
- Concentration
How does temperature increase affect enzyme activity?
It accelerates the rate.
What is the Temperature Coefficient?
- Denoted by symbol Q10
- Shows how much the rate increases with a 10°C temperature increase.
What happens when the temperatures surpasses the optimum value?
The enzyme begins to denature, meaning that the vibrations caused by KE from the temp. increase changes the tertiary structure of the enzyme, meaning that it is no longer complimantary to the substrate.
What is the Optimum Temperature for most enzymes in the human body?
40°C
What is the Optimum Temperature for most enzymes in thermophilic bacteria?
70°C
What is the Optimum Temperature for most enzymes in psychrophilic bacteria?
> 5°C
What is the structure of enzymes in cold extremes?
Flexible structures, particularly at active site. This is good for cold temps, but means that any slight temperature change will be enough to denature the enzyme.
