unit 1 test Flashcards
homeostasis definition
maintenance of a constant internal environment
relationship between insulin and glucagon
glucagon keeps blood glucose going too low.
insulin is to keep blood glucose from rising too high.
They stabilize blood glucose together.
Name 2 examples of altered homeostasis
Diabetes, hyperthermic, hypothermia
Compare and contrast positive and negative feedback loops
Positive is to increase the change or output.
Negative is to reduce the change or output (back to stable state).
negative or positive feedback:
If blood temperature rises too high, specialized neurons in the hypothalamus of the brain sense the change. These neurons signal other nerve centers, which in turn send signals to the blood vessels of the skin. As these blood vessels dilate, more blood flows close to the body surface and excess heat radiates from the body.
negative feedback
negative or positive feedback
Part of the complex biochemical pathway of blood clotting is the production of an enzyme that forms the matrix of the blood clot. This has a self- catalytic, or self-accelerating effect, so that once the clotting process begins, it runs faster and faster until, ideally, bleeding stops.
positive feedback
negative or positive feedback:
During childbirth stretching of the uterus triggers the secretion of the hormone oxytocin, which stimulates uterine contractions and speeds up labor.
positive feedback
negative or positive feedback:
The walls of arteries stretch in the presence of high blood pressure. Baroreceptors located in these walls also stretch and as a result, a signal is sent to the brain which in turn slows down the body’s heart rate. This slows the flow of blood through the arteries causing less pressure. As BP drops the baroreceptors become flaccid and a signal is sent to speed up the heart rate.
negative feedback
Endotherm vs ectotherm
Endotherms use internal heat for body temperature.
Ectotherms use external heat, and their body temperature changes with the temperature of the environment.
How does pH affect enzyme activity?
differences in pH can denature the enzyme
How does temperature affect enzyme activity?
increasing the temperature increases rate of the reaction, but there’s an optimal temp for each enzyme. Once the temperature exceeds it, the enzyme starts to denature
How does substrate concentration affect enzyme activity?
increases the rate of the reaction but once all of the active sites are occupied, then the rate of the reaction begins to plateau
How does enzyme concentration affect enzyme activity?
increases rate of the reaction b/c there are more active sites available
Where does a noncompetitive inhibitor bind to an enzyme?
allosteric site
Compare and contrast competitive and noncompetitive inhibitors
both stop the enzyme from doing its job.
The competitive occupies the active site and prevents the substrate from binding.
The noncompetitive attaches to the allosteric site, which changes the shape of the active site and the substrate can no longer bind.
True or False: An enzyme is one size fits all
False. An enzyme is substrate specific.
Name the two hypotheses used to describe how a substrate fits into an enzyme. Which one is the more widely accepted explanation?
lock and key hypothesis and induced fit model. The induced fit model is the one most widely accepted
What is the purpose of an enzyme?
speed up chemical reactions by lowering activation energy
Enzymes are known as ________
biological catalysts
Because anabolic reactions require/consume energy, they are classified as ____________ reactions
endothermic
Anabolic reactions are carried out by this process
dehydration synthesis
Anabolic reactions _________energy
require/consume
Anabolic reactions (anabolism) is ______
A chemical reaction that builds more complex organic molecules from simpler substances
Catabolic reactions are carried out by this process
hydrolysis
because catabolic reactions release energy, they are classified as _________ reactions
exothermic
