Enzymes and Energy 105- What two pH values produce half-maximal activity of
salivary amylase? - What two pH values produce half-maximal activity of
pepsin? - At what pH is the activity of pepsin and salivary amylase
equal? - Gastric juice normally has a pH of 2. Given this, what
happens to the activity of salivary amylase, a starch-
digesting enzyme in saliva, when it arrives in the stomach?
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pHEnzyme activity6810Pepsin Salivary
amylaseTrypsin- A student, learning that someone has an elevated blood level
of lactate dehydrogenase (LDH), wonders how the enzyme
got into this person’s blood and worries about whether it will
digest the blood. What explanation can you give to allay the
student’s fears? - Suppose you come across a bottle of enzyme tablets at your
local health food store. The clerk tells you this enzyme
will help your digestion, but you notice that it is derived
from a plant. What concerns might you have regarding the
effectiveness of these tablets? - Describe the energy transformations that occur when sunlight
falls on a field of grass, the grass is eaten by a herbivore (such
as a deer), and the herbivore is eaten by a carnivore (such as
a cougar). Use the laws of thermodynamics to explain why
there is more grass than deer, and more deer than cougars (in
terms of their total biomass). - Use the reversible reactions involving the formation and
breakdown of carbonic acid, and the law of mass action,
to explain what would happen to the blood pH of a
person who is hypoventilating (breathing inadequately) or
hyperventilating (breathing excessively).
Test Your Quantitative Ability
Use the graph here and in figure 4.4 to answer the following
questions:
- What are the pH optima of these three enzymes?
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