Biology (Raven), 10th Edition

Chapter 9: Cell Communication


Which of the following is usually NOT true of the protein kinase cascade?
A)The signal is amplified.
B)A second messenger is formed.
C)Target proteins are phosphorylated.
D)The cascade ends up in the nucleus where gene transcription is altered.
E)The cascade begins outside the plasma membrane
A protein kinase is an enzyme that
A)becomes active in all signal transduction events.
B)adds phosphate groups to certain proteins.
C)cannot be part of an actual receptor.
D)only activates target proteins.
E)is not affected by second messengers.
Which of the following are common secondary messengers?
D)Nitric Oxide
E)All of the above
Why are some ligand substances potential carcinogens?
A)They can stimulate the cell to divide too often.
B)They can trick a cell into creating more surface receptors.
C)By binding to a receptor, they have ambiguous messages.
D)The binding of ligand causes the release of mutagens.
E)The bind of ligand causes the release of free radicals.
Why are receptor proteins important to a cell's well-being?
A)Some messengers cannot cross the plasma membrane and therefore need a mechanism to activate a response
B)Cells are very busy centers of activity and therefore need to have a mechanism to "wake them up" and respond
C)Proteins are simple structures and need sophisticated mechanisms to enable them to do their job
D)Proteins accidentally bind to sugars, and it's the receptor proteins which correct these mistakes
E)Receptor proteins stimulate ribosomes to create proteins appropriate for the signaled event
A ligand is most accurately defined as a(n)
A)transcription factor that promotes increased production of a particular protein in response to an environmental change.
B)receptor molecule that binds a signaling molecule sent from another cell.
C)enzyme that alters cellular metabolism as a response to a received signal.
D)cytoskeletal element that alters its shape to promote movement of a cell.
E)signaling molecule that binds to a cellular receptor.
Which method of communication is most often observed between nerve cells?
B)Direct contact
What is a ligand?
A)Something that crosses the plasma membrane
B)A molecule which infuses itself into the fatty acid region of a phospholipids bilayer
C)Structures which contain a lot of energy
D)A substance which binds to receptors on the surface of a cell
E)A chemical which alters the primary structure of a protein
Recall from chapter 3, that protein domains are important in the function of the protein. What is the minimum number of functional domains required for a typical intracellular receptor protein?
What is the purpose of signal amplification?
A)It stimulates many pathways that will all result in the same outcome.
B)It allows for different messages to be created during a signaling event.
C)It is the mechanism of protein phosphorylation.
D)It allows a threshold to be achieved so that a dilute ligand can quickly cause a reaction.
E)to cause positive feedback creating an ever increasing reaction rate.
Neurotransmitters being released from a nerve cell and binding to another nerve cell or a muscle cell would be an example of which one of the following types of cell communication?
A)endocrine signaling
B)autocrine signaling
C)paracrine signaling
D)direct intercellular signaling
E)contact dependent signaling
Which of these activates G proteins by binding to them?
Arrange the stages of cell signaling in order from first to last.
i. cellular response
ii. receptor activation
iii. signal transduction
A)i, ii, iii
B)ii, iii, i
C)iii, i, ii
D)iii, ii, i
E)ii, i, iii
The receptor for the steroid hormone estrogen is found
A)at the extracellular face of the cytoplasmic membrane.
B)at the cytosolic face of the cytoplasmic membrane.
C)in the cytoplasm.
D)at the outer membrane of the nuclear envelope.
E)in the nucleus.
An enzyme that transfers a phosphate group to another molecule is called a ________, and an enzyme that removes a phosphate group from another molecule is called a ________.
A)kinase; phosphatase
B)phosphatase; dephosphatase
C)phosphodiesterase; kinase
D)cyclase; phosphodiesterase
E)phosphatase; kinase
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