MCBL Exam 1 (lecture 2)
The targets that lie at the end of signaling pathways are generally called - correct answer ✔✔effector
proteins
is a type of cell-cell or cell- extracellular matrix signaling in multicellular organisms that requires close
contact. Extracellular signal molecules remain bound to the surface of the signaling cell and influence
only cells that contact it. - correct answer ✔✔contact-dependent signaling
In most cases, however, signaling cells secrete signal molecules into the extracellular fluid. Often, the
secreted molecules are local mediators, which act only on nearby cells in the local environment of the
signaling cell. This is called - correct answer ✔✔paracrine signaling.
The signaling and target cells in paracrine signaling are of different cell types, but cells may also produce
signals that they themselves respond to: this is referred to as - correct answer ✔✔autocrine signaling
Endocrine signaling depends on endocrine cells, which secrete hormones into the bloodstream for
distribution throughout the body. These types of signals usually produce a ___ response but have a
____-lasting effect - correct answer ✔✔slower, longer
Hormones travel the large distances between endocrine cells and their target cells via the ____, which is
a relatively slow way to move throughout the body. Because of their form of transport, hormones get
diluted and are present in low concentrations when they act on their target cells. This is different from
paracrine signaling, in which local concentrations of ligands can be very high - correct answer
✔✔bloodstream
is performed by neurons that transmit signals electrically along their axons and release
neurotransmitters at synapses - correct answer ✔✔Synaptic signaling
A nerve cell consists of a cell body, several short, branched extensions called ___ that receive stimuli,
and a long extension called an ___, which transmits signals to other nerve cells or muscle cells. The
junction between nerve cells where signal transmission occurs is called a ____. - correct answer
✔✔dendrites, axon, synapse
, The distance between the presynaptic cell and the postsynaptic cell—called the _____— is very small
and allows for rapid diffusion of the neurotransmitter - correct answer ✔✔synaptic gap
Enzymes in the ___ degrade some types of neurotransmitters to terminate the signal. - correct answer
✔✔synaptic cleft
Difference between endocrine and synaptic signaling - correct answer ✔✔Endocrine cells secrete
hormones into the blood, which signal only the specific target cells that recognize them. Slow and long-
lasting signal transduction.
In synaptic signaling, by contrast, specificity arises from the synaptic contacts between a nerve cell and
the specific target cells it signals. Fast and short-lived signaling.
Identify each type of intercellular signaling - correct answer ✔✔
Most signal molecules are _____ and are therefore unable to cross the target cell's plasma membrane
directly - correct answer ✔✔hydrophilic
Some ____ signal molecules, by contrast, diffuse across the plasma membrane and bind to receptor
proteins inside the target cell. Many of these small signal molecules are ____ - correct answer ✔✔small,
hydrophobic
Some intracellular signaling molecules are small chemicals, which are often called ____ - correct answer
✔✔second messengers
Some second messengers, such as cyclic AMP and Ca2+, are water-soluble and diffuse in the ___, while
others, such as diacylglycerol, are lipid-soluble and diffuse in the plane of the____. - correct answer
✔✔cytosol, plasma membrane
Most intracellular signaling molecules are proteins, which behave like molecular switches:
Phosphorylation: protein kinase vs protein phosphatase (human genome encodes about 520 protein
kinases and about 150 protein phosphatases) GTP-binding proteins: These proteins switch between an
"on" (actively signaling) state when ___ is bound, and an "off" state when ___ is bound - correct answer
✔✔GTP, GDP
The targets that lie at the end of signaling pathways are generally called - correct answer ✔✔effector
proteins
is a type of cell-cell or cell- extracellular matrix signaling in multicellular organisms that requires close
contact. Extracellular signal molecules remain bound to the surface of the signaling cell and influence
only cells that contact it. - correct answer ✔✔contact-dependent signaling
In most cases, however, signaling cells secrete signal molecules into the extracellular fluid. Often, the
secreted molecules are local mediators, which act only on nearby cells in the local environment of the
signaling cell. This is called - correct answer ✔✔paracrine signaling.
The signaling and target cells in paracrine signaling are of different cell types, but cells may also produce
signals that they themselves respond to: this is referred to as - correct answer ✔✔autocrine signaling
Endocrine signaling depends on endocrine cells, which secrete hormones into the bloodstream for
distribution throughout the body. These types of signals usually produce a ___ response but have a
____-lasting effect - correct answer ✔✔slower, longer
Hormones travel the large distances between endocrine cells and their target cells via the ____, which is
a relatively slow way to move throughout the body. Because of their form of transport, hormones get
diluted and are present in low concentrations when they act on their target cells. This is different from
paracrine signaling, in which local concentrations of ligands can be very high - correct answer
✔✔bloodstream
is performed by neurons that transmit signals electrically along their axons and release
neurotransmitters at synapses - correct answer ✔✔Synaptic signaling
A nerve cell consists of a cell body, several short, branched extensions called ___ that receive stimuli,
and a long extension called an ___, which transmits signals to other nerve cells or muscle cells. The
junction between nerve cells where signal transmission occurs is called a ____. - correct answer
✔✔dendrites, axon, synapse
, The distance between the presynaptic cell and the postsynaptic cell—called the _____— is very small
and allows for rapid diffusion of the neurotransmitter - correct answer ✔✔synaptic gap
Enzymes in the ___ degrade some types of neurotransmitters to terminate the signal. - correct answer
✔✔synaptic cleft
Difference between endocrine and synaptic signaling - correct answer ✔✔Endocrine cells secrete
hormones into the blood, which signal only the specific target cells that recognize them. Slow and long-
lasting signal transduction.
In synaptic signaling, by contrast, specificity arises from the synaptic contacts between a nerve cell and
the specific target cells it signals. Fast and short-lived signaling.
Identify each type of intercellular signaling - correct answer ✔✔
Most signal molecules are _____ and are therefore unable to cross the target cell's plasma membrane
directly - correct answer ✔✔hydrophilic
Some ____ signal molecules, by contrast, diffuse across the plasma membrane and bind to receptor
proteins inside the target cell. Many of these small signal molecules are ____ - correct answer ✔✔small,
hydrophobic
Some intracellular signaling molecules are small chemicals, which are often called ____ - correct answer
✔✔second messengers
Some second messengers, such as cyclic AMP and Ca2+, are water-soluble and diffuse in the ___, while
others, such as diacylglycerol, are lipid-soluble and diffuse in the plane of the____. - correct answer
✔✔cytosol, plasma membrane
Most intracellular signaling molecules are proteins, which behave like molecular switches:
Phosphorylation: protein kinase vs protein phosphatase (human genome encodes about 520 protein
kinases and about 150 protein phosphatases) GTP-binding proteins: These proteins switch between an
"on" (actively signaling) state when ___ is bound, and an "off" state when ___ is bound - correct answer
✔✔GTP, GDP
