AP Bio Chapter 9 Quiz
What is the function of a phosphatase?
A phosphatase removes the phosphate group from phosphorylated amino acid residues in a protein.
The bioluminescent bacteria Vibrio fischeri produces luminescence only if the population reaches a certain density. What is the advantage of an autoinducer?
An autoinducer allows a positive feedback loop, which increases the response in proportion to the population size.
. The secretion of hormones by the pituitary gland is an example of which type of signaling?
Endocrine Signaling
Why are ion channels necessary to transport ions into or out of a cell?
Ions are charged particles and cannot diffuse through the hydrophobic interior of the membrane.
Aldosterone is a steroid hormone that regulates reabsorption of sodium ions in the kidney tubular cells. What is the probable mechanism of action of aldosterone?
It binds to an intracellular receptor and activates gene transcription.
The gas nitric oxide has been identified as a signaling molecule. Which of the following mechanisms of action would you expect from a gaseous molecule?
It binds to an intracellular receptor.
How does NF-κB induce gene expression?
Phosphorylation of the inhibitor IκB dissociates the complex between it and NF-κB, allowing NF-κB to enter the nucleus and stimulate transcription.
Why are endocrine signals transmitted more slowly than paracrine signals?
The ligands are transported through the bloodstream and travel greater distances.
Which of the following properties prevents the ligands of cell-surface receptors from entering the cell?
The molecules are hydrophilic and cannot penetrate the hydrophobic interior of the plasma membrane.
The hormone insulin binds to a receptor tyrosine kinase on the surface of target cells. Which of the following steps takes place before phosphorylation of tyrosine residues?
The receptor forms a dimer.
Where do DAG and IP3 originate?
They are the cleavage products of the inositol phospholipid, PIP2.
What property enables the residues of the amino acids serine, threonine, and tyrosine to be phosphorylated?
They contain a hydroxyl group.
When is quorum sensing triggered to begin?
a sufficient number of bacteria are present
Epinephrine mediates the fight-or-flight response of the body. One of the effects is to increase the amount of glucose available to muscles. What does the signaling pathway triggered by epinephrine cause to occur in liver cells?
activation of metabolism
Cancer cells that continue to divide when defective often show changes in what cellular function?
apoptosis
Dopamine is a neurotransmitter in the brain that causes long-term responses in neurons and binds to a G-protein-linked receptor. Which of the following chemicals would you expect to increase in concentration after dopamine binds its receptor?
cAMP
Target Cell
cell that has a receptor for a signal or ligand from a signaling cell
Endocrine Cell
cell that releases ligands involved in endocrine signaling (hormones)
Dimer
chemical compound formed when two molecules join together
Growth Factor
ligand that binds to cell-surface receptors and stimulates cell growth inhibitor molecule that binds to a protein (usually an enzyme) and keeps it from functioning
Calvin Cycle
light-independent reactions of photosynthesis that convert carbon dioxide from the atmosphere into carbohydrates using the energy and reducing power of ATP and NADPH
Which type of molecule acts as a signaling molecule in yeasts?
mating factor
Quorum Sensing
method of cellular communication used by bacteria that informs them of the abundance of similar (or different) bacteria in the environment
Inhibitor
molecule that binds to a protein (usually an enzyme) and keeps it from functioning
Yeast releasing mating factor can be classified as which type of signal?
paracrine
Carbon Fixation
process of converting inorganic CO2 gas into organic compounds
Apoptosis
programmed cell death
Signal Transduction
propagation of the signal through the cytoplasm (and sometimes also the nucleus) of the cell
Receptor
protein in or on a target cell that bind to ligands
Autoinducer
signaling molecule secreted by bacteria to communicate with other bacteria of its kind and others
Mating factor
signaling molecule secreted by yeast cells to communicate to nearby yeast cells that they are available to mate and communicating their mating orientation
