Chapter 11 Cell Communication
Chapter 12 Cell Cycle
an enzyme that converts ATP to cyclic AMP in response to a signal
the strengthening of stimulus energy during transduction
a program of controlled cell suicide, which is brought about by signals that trigger the activation of a cascade of suicide proteins in the cell destined to die
a surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation
cyclic AMP (cAMP)
a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells
the contents of the cell, exclusive of the nucleus and bounded by the plasma membrane
a second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane
a catecholamine that, when secreted as a hormone by the adrenal medulla, mediates "fight-or-flight" responses to short-term stresses
a GTP-binding protein that relays signals from a plasma membrane signal receptor to other signal transduction proteins inside the cell
a type of intercellular junction in animals that allows the passage of materials between cells
an extensively branched glucose storage polysaccharide found in the liver and muscle of animals
inositol trisphosphate (IP3)
a second messenger that functions as an intermediate between certain nonsteroid hormones and a third messenger, a rise in cytoplasmic Ca2+ concentration
a molecule that binds specifically to another molecule, usually a larger one
ligand-gated ion channel
a protein pore in cellular membranes that opens or closes in response to a signaling chemical (its ligand), allowing or blocking the flow of specific ions
a secreted molecule that influences cells near where it is secreted
nitric oxide (NO)
a gas produced by many types of cells that functions as a local regulator and as a neurotransmitter
an enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein
an enzyme that removes phosphate groups from (dephosphorylates) proteins, often functioning to reverse the effect of a protein kinase
receptor tyrosine kinase
a receptor protein in the plasma membrane, the cytoplasmic part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein
a type of large relay protein to which several other relay proteins are simultaneously attached, increasing the efficiency of signal transduction
a small, nonprotein, water-soluble molecule or ion that relays a signal to a cell's interior in response to a signaling molecule bound by a signal receptor protein
the linkage of a mechanical, chemical, or electromagnetic stimulus to a specific cellular response
signal transduction pathway
a series of steps linking a mechanical or chemical stimulus to a specific cellular response
a steroid hormone required for development of the male reproductive system, spermatogenesis, and male secondary sex characteristics
a regulatory protein that binds to DNA and affects transcription of specific genes
the conversion of a signal from outside the cell to a form that can bring about a specific cellular response
Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because (?)
they amplify the original signal manyfold
Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
ligand-gated ion channel
The activation of receptor tyrosine kinases is characterized by (?)
dimerization and phosphorylation
Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?
Glycogen breakdown was observed only when epinephrine was administered to intact cells.
Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because (?)
intracellular receptors are present only in target cells
Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.
Which of these is a receptor molecule? (A-E)
A signal transduction pathway is initiated when a (?) binds to a receptor.
Which of these is a signal molecule? (A-E)
A signal molecule is also known as a(n) (?).
Which of these receptors is NOT a membrane receptor? (A-E)
Which of these is a G-protein-linked receptor? (A-E)
Which of these is a receptor tyrosine kinase? (A-E)
Which of these is an ion-channel receptor? (A-E)
The binding of signal molecules to (A-E) results in the phosphorylation of tyrosines.
Which of these receptor molecules would allow Na+ to flow into the cell? (A-E)
Which extracellular signal molecule could diffuse through a plasma membrane and bind to an intracellular receptor?
A(n) (?) is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.
(?) is a signal molecule that binds to an intracellular receptor.
Thyroid hormones bind to (?) receptors.
Which of these acts as a second messenger? (A-E)
Calcium ions that act as second messengers are stored in (?).
(1) catalyzes the production of (2), which then opens an ion channel that releases (3) into the cell's cytoplasm.
1) Phospholipase C 2) IP3 3) Ca2+
A protein kinase activating many other protein kinases is an example of (?).
The cleavage of glycogen by glycogen phosphorylase releases (?).
Epinephrine acts as a signal molecule that attaches to (?) proteins.
A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to (?) receptors.
Evidence that cell signaling evolved early in the history of life comes from (?).
the similarity of the mechanisms in organisms that have a very distant common ancestor
When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane A2. Thromboxane A2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example thromboxane A2 is acting as a (?).
Early work on signal transduction and glycogen depolymerization by Sutherland indicated that (?).
the signal molecule did not interact directly with the cytosolic enzyme, but required an intact plasma membrane before the enzyme could be activated
Certain yeast cells secrete a molecule called the α factor. The purpose of this molecule is to (?).
stimulate an a yeast cell to grow toward the α cell
Cells use different signaling strategies to achieve different goals. In hormonal signaling, (?).
specialized cells release hormone molecules into the circulatory system, permitting distant cells to be affected
Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence?
Nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell's nucleus.
Steroid hormones can enter a cell by simple diffusion. Therefore steroids (?).
do not initiate cell signaling by interacting with a receptor in the plasma membrane
A small molecule that specifically binds to a larger molecule is called a(n) (?).
Receptors for signal molecules (?).
can be found as part of the plasma membrane or found within the cytoplasm
Testosterone does not affect all cells of the body because (?).
not all cells have cytoplasmic receptors for testosterone