MCB 150 Quest #3 With Complete Solutions
signals are relayed between cells in five common ways - ANSWER direct
intercellular signaling, contact-dependent, autocrine, paracrine, endocrine
direct intercellular signaling - ANSWER cells adjacent to each other may have
cell junctions that enable them to pass ions, signaling molecules, and other
materials between the cytosol of one cell to the cytosol of another cell
Contact-Dependent signaling - ANSWER One cell has a membrane-bound
signaling molecule that is recognized by a receptor on the surface of another
cell
autocrine signaling - ANSWER a cell secretes signaling molecules that bind to
receptors on its own cell surface and on the surface of neighboring cells of the
same cell type, stimulating a response
paracrine signaling - ANSWER a specific cell secretes a signaling molecule that
does not affect the cell secreting the signal but instead influences the behavior
of target cells in close proximity
endocrine signaling - ANSWER occurs over relatively long distance
Hormones - ANSWER long-distance signaling in both animals and plants
-last longer than signaling molecules involved in autocrine and paracrine
signaling
Cells respond to signals via a three-stage process: - ANSWER receptor
activation, signal transduction, cellular response
Receptor Activation - ANSWER A signaling molecule binds to a receptor of the
target cell, causing a conformational change in the receptor that activates it
Signaling Transduction - ANSWER The initial signal is converted or transduced
to a different signal inside the cell carried out by a group of proteins
Cellular Response - ANSWER -Altering the activity of one or more enzymes
-Altering the functions of structural proteins
-The function of transcription factors - proteins that regulate the transcription of
genes. May activate gene expression.
Mode of cell communication depends on... - ANSWER distance
, The signaling molecule, _________, binds noncovalently to the receptor with a
high degree of specificity - ANSWER ligands
Kon - ANSWER rate at which binding occurs
[Ligand} + {RECEptor} + {Ligand x receptor complex} - ANSWER the brackets
indicate concentration
-after complex forms, the noncovalent interaction between ligand and receptor
remains stable for a finite period of time
Koff - ANSWER The rate constant for dissociation of a ligand from its receptor.
kd - ANSWER dissociation between the ligand and receptor
-low kd indicates that a receptor has a high affinity for its ligand
What happens when the ligand concentration is above the kd value? - ANSWER
most receptors are likely to have ligand bount to them
-if the ligand conc is below the kd value, most receptors will not be bound by
their ligand
enzyme-linked receptors - ANSWER receptors found in all living species, many
human hormones bind to this type of receptor
G-protein-coupled receptors - ANSWER Found in eukaryotic species,
particularly common in animals (ability to bind GTP and GDP)
-GTP --> needed for receptors to cause an intracellular response
1) a signaling molecule binds to a GPCR, causing it to bind to a G protein
2) The G protein exchanges GDP for GTP. The G protein then dissociates from
the receptor and separates into an active a subunit and b/y dimer. The activated
subunits promote cellular response.
Ligand-Gated Ion Channels - ANSWER -Found in the plasma membranes of
animal, plant, and fungal cells
-When ligand (signaling molecule) binds to this recpetor, the ion channel opens
and allows the flow of ions through the membrane, changing the concentration
of ions in the cell
-Changes in the cytosis concentration of Ca+ often play a role in signal
transduction
receptors for steriod hormones are intracellular - ANSWER estrogens
(hydrophobic) and androgens are secreted into the bloodstream from cells of
endocrine glands
1) Estrogen diffuses across the plasma membrane, enters the nucleus, and
binds to estrogen receptor subunits
signals are relayed between cells in five common ways - ANSWER direct
intercellular signaling, contact-dependent, autocrine, paracrine, endocrine
direct intercellular signaling - ANSWER cells adjacent to each other may have
cell junctions that enable them to pass ions, signaling molecules, and other
materials between the cytosol of one cell to the cytosol of another cell
Contact-Dependent signaling - ANSWER One cell has a membrane-bound
signaling molecule that is recognized by a receptor on the surface of another
cell
autocrine signaling - ANSWER a cell secretes signaling molecules that bind to
receptors on its own cell surface and on the surface of neighboring cells of the
same cell type, stimulating a response
paracrine signaling - ANSWER a specific cell secretes a signaling molecule that
does not affect the cell secreting the signal but instead influences the behavior
of target cells in close proximity
endocrine signaling - ANSWER occurs over relatively long distance
Hormones - ANSWER long-distance signaling in both animals and plants
-last longer than signaling molecules involved in autocrine and paracrine
signaling
Cells respond to signals via a three-stage process: - ANSWER receptor
activation, signal transduction, cellular response
Receptor Activation - ANSWER A signaling molecule binds to a receptor of the
target cell, causing a conformational change in the receptor that activates it
Signaling Transduction - ANSWER The initial signal is converted or transduced
to a different signal inside the cell carried out by a group of proteins
Cellular Response - ANSWER -Altering the activity of one or more enzymes
-Altering the functions of structural proteins
-The function of transcription factors - proteins that regulate the transcription of
genes. May activate gene expression.
Mode of cell communication depends on... - ANSWER distance
, The signaling molecule, _________, binds noncovalently to the receptor with a
high degree of specificity - ANSWER ligands
Kon - ANSWER rate at which binding occurs
[Ligand} + {RECEptor} + {Ligand x receptor complex} - ANSWER the brackets
indicate concentration
-after complex forms, the noncovalent interaction between ligand and receptor
remains stable for a finite period of time
Koff - ANSWER The rate constant for dissociation of a ligand from its receptor.
kd - ANSWER dissociation between the ligand and receptor
-low kd indicates that a receptor has a high affinity for its ligand
What happens when the ligand concentration is above the kd value? - ANSWER
most receptors are likely to have ligand bount to them
-if the ligand conc is below the kd value, most receptors will not be bound by
their ligand
enzyme-linked receptors - ANSWER receptors found in all living species, many
human hormones bind to this type of receptor
G-protein-coupled receptors - ANSWER Found in eukaryotic species,
particularly common in animals (ability to bind GTP and GDP)
-GTP --> needed for receptors to cause an intracellular response
1) a signaling molecule binds to a GPCR, causing it to bind to a G protein
2) The G protein exchanges GDP for GTP. The G protein then dissociates from
the receptor and separates into an active a subunit and b/y dimer. The activated
subunits promote cellular response.
Ligand-Gated Ion Channels - ANSWER -Found in the plasma membranes of
animal, plant, and fungal cells
-When ligand (signaling molecule) binds to this recpetor, the ion channel opens
and allows the flow of ions through the membrane, changing the concentration
of ions in the cell
-Changes in the cytosis concentration of Ca+ often play a role in signal
transduction
receptors for steriod hormones are intracellular - ANSWER estrogens
(hydrophobic) and androgens are secreted into the bloodstream from cells of
endocrine glands
1) Estrogen diffuses across the plasma membrane, enters the nucleus, and
binds to estrogen receptor subunits
