BI 255 EXAM QUESTIONS AND ANSWERS
LATEST UPDATE
What is the enzyme that breaks down lactose?
lactase
If you are lactose tolerant, do all the cells of your body produce lactase?
no, only the small intestine
Is it normal to make lactase in adulthood?
no, it typically goes away after infancy
- producing lactase in adulthood is considered to be a mutation and is called lactase
permanence
What does cobra venom do to anything it touches?
it melts everything
- it digests the cell membranes
What enzyme is in cobra venom? What does it do?
- contains Phospholipase A2
- clips one of the fatty acid tails off a phospholipid --> because of this the phospholipids
don't want to form a lipid bilayer spontaneously and instead form a micelle
- in a micelle, they can not hold in cellular material and therefore let all material out
Which is more stable: a micelle or a lipid bilayer?
lipid bilayer
What does the drug sildenafil (Viagra) do?
- binds to the active site of phosphodiesterase 5 (PDE5) causing inhibition
- causes widening in arteries to the penis
What is a coenzyme?
a small (non-protein) organic molecule that enhances protein activity
What does a coenzyme do?
- Acts as a "helper" in order for the substrate to bind (modifies the active site)
- Fills in part of the active site in order for different substrates to work
What are typically considered to be coenzymes in the human body?
vitamins
What is the role of folic acid?
a coenzyme that is required for neural tube development (helps to prevent misfiling of
the neural fold and neural groove during early development)
- commonly found in prenatal vitamins
What is the role of vitamin C (ascorbic acid)?
a coenzyme required for collagen synthesis (btw collagen is needed for structure all
throughout your body)
- lack of vitamin c leads to scurvy
What is the role of thiamine (vitamin B1)?
LATEST UPDATE
What is the enzyme that breaks down lactose?
lactase
If you are lactose tolerant, do all the cells of your body produce lactase?
no, only the small intestine
Is it normal to make lactase in adulthood?
no, it typically goes away after infancy
- producing lactase in adulthood is considered to be a mutation and is called lactase
permanence
What does cobra venom do to anything it touches?
it melts everything
- it digests the cell membranes
What enzyme is in cobra venom? What does it do?
- contains Phospholipase A2
- clips one of the fatty acid tails off a phospholipid --> because of this the phospholipids
don't want to form a lipid bilayer spontaneously and instead form a micelle
- in a micelle, they can not hold in cellular material and therefore let all material out
Which is more stable: a micelle or a lipid bilayer?
lipid bilayer
What does the drug sildenafil (Viagra) do?
- binds to the active site of phosphodiesterase 5 (PDE5) causing inhibition
- causes widening in arteries to the penis
What is a coenzyme?
a small (non-protein) organic molecule that enhances protein activity
What does a coenzyme do?
- Acts as a "helper" in order for the substrate to bind (modifies the active site)
- Fills in part of the active site in order for different substrates to work
What are typically considered to be coenzymes in the human body?
vitamins
What is the role of folic acid?
a coenzyme that is required for neural tube development (helps to prevent misfiling of
the neural fold and neural groove during early development)
- commonly found in prenatal vitamins
What is the role of vitamin C (ascorbic acid)?
a coenzyme required for collagen synthesis (btw collagen is needed for structure all
throughout your body)
- lack of vitamin c leads to scurvy
What is the role of thiamine (vitamin B1)?
