Lab 1: Enzyme Metabolism Flashcards
Enzymes are an example of what kind of interaction%
Protein-protein interaction
How do enzymes speed up the rate of a reaction?
By lowering the activation energy
Enzymes can catalyze reactions at rates up to ________ billion times higher than comparable non-catalyzed reactions
10 billion times
How do enzymes lower the energy of activation? (2)
By their specific configuration, they can:
1) Hold the reactant molecules in close proximity
2) Hold the reactant molecules in the correct orientation
Where do substrates and enzymes combine?
Active site
The specificity of an enzyme is due to what?
Their structure
What happens when an enzyme is subjected to high temperatures?
The enzyme ceases to function
What happens when an enzyme is subjected to low temperatures?
The enzyme is inactive, but not permanently denatured
What is lactose composed of?
Glucose and galactose
Lactose has been shown to aid in the absorption of several minerals, such as what?
- Calcium
- Magnesium
- Zinc
What is the cause of lactose intolerance?
Due to little or no activity of lactase, which prevents lactose from being broken down into glucose and galactose
What happens if there is low lactase activity in the small intestine?
Undigested lactose is passed into the colon where bacteria ferment the sugar to hydrogen gas and organic acids
An inadequate intake of calcium can lead to which kinds of diseases?
- Rickets
- Osteoporosis
- Hypertension
Where is the gene for the production of lactase located on?
Chromosome 2
What is the difference in DNA in individuals with lactase activity and without?
There isn’t any
What does the difference in mRNA in individuals with lactase activity and without indicate?
Indicates that the primary regulation of the enzyme occurs during translation
What type of sugars are located in cow, soy, and rice milks?
- Cow: lactose
- Soy: sucrose
- Rice: glucose
What was the glucose composition of soy milk before lactase was added? What about after?
- Before: negative
- After: negative
What was the glucose composition of cow’s milk before lactase was added? What about after?
- Before: negative
- After: positive (1/4)
What was the glucose composition of rice milk before lactase was added? What about after?
- Before: positive (2)
- After: positive (2)
How did the relative amount of glucose change depending on the pH of lactase?
2: negative
5: 1/10
7: 1/4
9: 1/4
12: negative
At which pH is lactase optimally active?
7-9
What is sucrose composed of?
Glucose and fructose
Why did lactase not function on sucrose?
Since the enzyme is specific to lactose
How do monosaccharides join to form the disaccharide lactose? What kind of bond is formed?
- Glucose and galactose undergo condensation to form lactose.
- An OH group from one monosaccharide and an H from the other combine to form water, which prompts the formation of the disaccharide
- β-1→4 glycosidic bond
Where is lactase produced? What is its role?
- Produced in the brush border of the small intestine
- Hydrolyzes the β-1→4 glycosidic bond in lactose into glucose and galactose
How does a hydrolase enzyme function?
- Through the addition of water, hydrolase enzymes cleave bonds
- One end receives an OH group, and another end receives the H+
How does pH affect enzymatic activity?
- pH may affect the charge/shape of the substrates
- If so, they cannot bind to the active site and cannot undergo catalysis
How does cold temperature affect enzymatic activity?
- Cold temperatures slow molecular movement
- Decreases enzyme activity due to less enzyme-substrate collisions
At what temperature is lactase optimally functional? What was the optimal temperature in this experiment?
- 37oC
- 25oC in this experiment (room temperature)
