Mastering Biology 4

Created by Livs93 

Upgrade to
remove ads

A signal transduction pathway is initiated when a _____ binds to a receptor.
a) cyclic AMP
b) tyrosine kinase
c) signal molecule
d) G protein
e) calmodulin

c) signal molecule

A signal molecule is also known as a(n) _____.
a) initiator
b) receptor
c) key
d) ligand
e) protein

d) ligand

Which of these is the second of the three stages of cell signaling?
a) gene activation
b) reception
c) binding of a neurotransmitter to a plasma membrane receptor
d) transduction
e) cell response

d) transduction

Paracrine signaling
a) has been found in plants but not animals.
b) involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid.
c) occurs only in paracrine yeast cells.
d) requires nerve cells to release a neurotransmitter into the synapse.
e) involves mating factors attaching to target cells and causing production of new paracrine cells.

b) involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid.

From the perspective of the cell receiving the message, the three stages of cell signaling are
a) the paracrine, local, and synaptic stages.
b) signal reception, nucleus disintegration, and new cell generation.
c) the alpha, beta, and gamma stages.
d) signal reception, signal transduction, and cellular response.
e) signal reception, cellular response, and cell division.

d) signal reception, signal transduction, and cellular response.

The process of transduction usually begins
a) when the signal molecule changes the receptor protein in some way.
b) after the third stage of cell signaling is completed.
c) after the target cell divides.
d) when the chemical signal is released from the alpha cell.
e) when the hormone is released from the gland into the blood.

a) when the signal molecule changes the receptor protein in some way.

When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signaling is
a) endocrine signaling.
b) synaptic signaling.
c) typical of hormones.
d) autocrine signaling.
e) paracrine signaling.

e) paracrine signaling

In general, a signal transmitted via phosphorylation of a series of proteins
a) cannot occur in yeasts because they lack protein phosphatases.
b) requires binding of a hormone to a cytosol receptor.
c) allows target cells to change their shape and therefore their activity.
d) requires phosphorylase activity.
e) brings a conformational change to each protein.

e) brings a conformational change to each protein.

The general name for an enzyme that transfers phosphate groups from ATP to a protein is
a) protease.
b) phosphorylase.
c) phosphatase.
d) ATPase.
e) protein kinase.

e) protein kinase

An inhibitor of phosphodiesterase activity would have which of the following effects?
a) decrease the amount of cAMP in the cytoplasm
b) block the activation of G proteins in response to epinephrine binding to its receptor
c) block the activation of protein kinase A
d) block the response of epinephrine
e) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm

e) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?
a) Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding.
b) Estrogen is kept away from the surface of any cells not able to bind it at the surface.
c) Estrogen is produced in very large concentration and therefore diffuses widely.
d) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding.
e) Estrogen has different shaped receptors for each of several cell types.

d) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding.

Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because
a) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.
b) only target cells possess the cytosolic enzymes that transduce the testosterone.
c) most cells lack the Y chromosome required.
d) intracellular receptors are present only in target cells.
e) only target cells retain the appropriate DNA segments.

d) 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.
a) adenylyl cyclase
b) GTP
c) G protein
d) cAMP
e) G protein-coupled receptor

d) cAMP

Use the following information to answer the following question.

Affinity chromatography is a method that can be used to purify cell-surface receptors, while they retain their hormone-binding ability. A ligand (hormone) for a receptor of interest is chemically linked to polystyrene beads. A solubilized preparation of membrane proteins is passed over a column containing these beads. Only the receptor binds to the beads.

This method of affinity chromatography would be expected to collect which of the following?
a) hormone-receptor complexes
b) molecules of the hormone
c) molecules of purified receptor
d) assorted membrane proteins
e) G proteins

c) molecules of purified receptor

Adenylyl cyclase has the opposite effect of which of the following?
a) protein phosphatase
b) phosphodiesterase
c) GTPase
d) phosphorylase
e) protein kinase

b) phosphodiesterase

Which of the following is a substance that acts at a long distance from the site at which it is secreted?
a) hormone
b) neurotransmitter
c) synaptic signal
d) local regulator
e) paracrine signal

a) hormone

To what does the term "ligand" refer in cell biology?
a) the bond that forms between a signaling molecule and its receptor
b) the target cell of a signal molecule
c) any small molecule that can bind in a specific manner to a larger one
d) the change in shape that occurs when a signaling molecule binds to its receptor
e) a molecule that can occupy a receptor site while not activating the receptor

c) any small molecule that can bind in a specific manner to a larger one

Why can a signaling molecule cause different responses in different cells?
a) Different cells have membrane receptors that bind to different sides of the signaling molecule.
b) Different cells possess different enzymes, which modify the signaling molecule into different molecules after it has arrived.
c) The transduction process is unique to each cell type; to respond to a signal, different cells require only a similar membrane receptor.
d) The transduction pathway in cells has a variable length.
e) All of the above are correct.

c) The transduction process is unique to each cell type; to respond to a signal, different cells require only a similar membrane receptor.

What is apoptosis?
a) a metabolic step in blood clotting
b) a way to stimulate transcription
c) a type of second messenger
d) controlled cell suicide
e) a type of membrane receptor

d) controlled cell suicide

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because
a) only target cells retain the appropriate DNA segments.
b) intracellular receptors are present only in target cells.
c) most cells lack the Y chromosome required.
d) only target cells possess the cytosolic enzymes that transduce the testosterone.
e) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.

b) intracellular receptors are present only in target cells.

What are the functions of signal transduction pathways?
a) Signal transduction pathways allow different types of cells to respond differently to the same signal molecule.
b) Signal transduction pathways convert a signal on a cell's surface to a specific cellular response.
c) Signal transduction pathways amplify the effect of a signal molecule.
d) all of the above

d) all of the above

Which statement correctly distinguishes the roles of protein kinases and protein phosphatases in signal transduction pathways?
a) Protein kinases activate enzymes by phosphorylating or adding phosphate groups to them. Protein phosphatases dephosphorylate or remove phosphate groups from enzymes, including protein kinases.
b) Protein kinases are involved in signal transduction in unicellular eukaryotes such as yeast. Protein phosphatases are involved in signal transduction in multicellular eukaryotes.
c) Protein kinases are more critical than protein phosphatases to signal transduction enzymes.

a) Protein kinases activate enzymes by phosphorylating or adding phosphate groups to them. Protein phosphatases dephosphorylate or remove phosphate groups from enzymes, including protein kinases.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set