Biology (Raven), 9th Edition

Chapter 9: Cell Communication

Post-Test

1
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
2
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.
3
Which of the following are common secondary messengers?
A)DAG
B)cAMP
C)Calcium
D)Nitric Oxide
E)All of the above
4
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.
5
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
6
Which type of cell junction would best serve to prevent cardiac (heart muscle) cells from separating?
A)Tight junctions
B)Gap Junctions
C)Desmosomes
D)Communicating junctions
E)All of the above are equally effective in preventing separation
7
Which method of communication is most often observed between nerve cells?
A)Paracrine
B)Direct contact
C)Synaptic
D)Endocrine
E)Electrical
8
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
9
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?
A)1
B)2
C)3
D)4
E)5
10
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.
11
The term "glycolipid" refers to a molecule constructed from which macromolecule classes?
A)Polysaccharides and nucleotides
B)Nucleic acids, polypeptides, and polysaccharides
C)Polypeptides, lipids, and nucleotides
D)Only polysaccharides and lipids
E)Only lipids and polypeptides
12
Which of these activates G proteins by binding to them?
A)GTP
B)GDP
C)ATP
D)ADP
E)CAMP
13
The receptor proteins that bind neurotransmitters
A)have multiple transmembrane domains.
B)are intracellular.
C)are translocated to the nucleus.
D)are autophosphorylated on the intracellular domain.
E)are protein kinases.
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