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Chupp Biology 121 Test 2
Terms in this set (97)
long and short
Cells can communicate over ________ distances.
bind to and activate cell-surface and intracellular receptors
G protein-coupled receptors
are a large, conserved family of receptors that often lead to short-term responses.
are widespread and often lead to long-term responses.
Signaling cells, Signaling molecule, Receptor molecule, Receptor cell
Communication between cells, whether prokaryotic or eukaryotic, involves these four essential elements.
signaling cell; signaling molecule; receptor protein; responding cell
The _____ releases a __________, which is recognized by the ________ on the __________.
low population density
At ______________, the concentration of the signaling peptide is too low to bind to the receptors and stimulate DNA uptake.
high population density
At _____________ the concentration of the signaling peptide is high enough to bind to the receptors and stimulate DNA uptake
1. receptor activation
2. signal transduction
3. cellular response
4. signal termination
Signaling between cells involves four steps:
Once the signaling molecule is bound to the receptor on the responding cell, the receptor is turned on, or
Once activated, the receptor on the responding cell transmits a message to the cell through the cytoplasm in a process called__________. This message can remain in the cytosol or go to the nucleus.
activate enzymes, turn on genes, signal other cells, and cause the cell to divide or change shape
the cell will RESPOND to the signal depending on what the response should be. It could _________
Once the signal has been received and acted upon, it is
endocrine, paracrine, aurocrine, contact-dependent signaling
signaling over long and short distances
Signaling by means of molecules traveling through the bloodstream is called
estrogen and testosterone
Examples of endocrine signaling molecules
involves two cells that are close to each other.
small, soluble molecule
In paracrine signaling, the signal is usually a
Some paracrine signal molecules are known as _______ because they stimulate cells to grow and divide.
occurs when the signaling cell and the responding cell are one and the same
Paracrine and autocrine signaling are especially important to multicellular organisms during
Some signaling occurs in the absence of a signaling molecule. Instead, it occurs because of direct contact between neighboring cells. This communication is .
the development of the central nervous system in vertebrates
One example of contact-dependent signaling occurs during
In the developing embryo, some undifferentiated cells begin to express a protein called ___on their surface.
This signal is received by all the cells directly touching the Delta-expressing cell, through a surface protein called
supporting glial cells
the Notch expressing cells become ___________ and not neurons.
The Delta-expressing cell develops into a
ligand binds to the ligand binding site
When a _______________ on its receptor, a conformational change in the receptor takes place that triggers chemical reactions to take place in the cytosol.
Small nonpolar signaling molecules
________ can freely pass through the plasma membrane and activate cytoplasmic receptors.
Nonpolar signaling molecules that can pass through the hydrophobic core of the plasma membrane don't need a _____ on the exterior side of the cell.
Polar signaling molecules
______ cannot cross the plasma membrane and rely on cell-surface receptors.
signaling molecule binds to the ligand-binding site
When a ______________, the entire receptor molecule undergoes a conformational change, activating the receptor.
G protein coupled receptors
3 types of cell surface receptors:
G protein-coupled receptors
are found in virtually every eukaryotic organism
G protein-coupled receptors associate with ___________ bound to GTP and GDP in the cytoplasm.
When a G protein is bound to GTP, it is
When a G protein is bound to GDP, it is
G protein-coupled receptor
When a ligand binds to a _______, the receptor binds to and activates the G protein by replacing GDP with GTP.
A ______ is an enzyme that adds a phosphate group to another molecule in a process called __________
have the opposite effect and remove a phosphate group.
active and is switched on
When a protein is phosphorylated by a kinase, it is
When ligand binds the ligand binding site, _______ become active, phosphorylating other proteins and transmitting the signal from outside the cell to inside the cell.
________ alter the flow of ions across the plasma membrane
voltage-gated ion channels
Some ion channels open in response to voltage changes across the membranes and are called
Other ion channels open when bound by their ligand and are called
The ________ is composed of microtubules, microfilaments, and intermediate filaments that help maintain cell shape.
connect cells to one another to form tissues.
provides structural support and informational cues.
shape and internal structural features
The function of a cell is reflected in its
carry oxygen and fit through blood vessels that are much smaller than itself
A red blood cell is shaped like a disk having an indented middle and lacks a nucleus or other organelles. This structure makes it possible for the cell to
Hepatocytes (liver cells) contain large amounts of __________ needed for protein synthesis.
Long, multinucleated muscle cells have a striped appearance and are specialized for
The shape of cells is determined and maintained by structural protein networks in the cytoplasm, the ____________
What structural integrity of a tissue or organ depends on
1. the ability of cells to adhere to one another, through the assembly of cytosolic proteins and other cell adhesion molecules, into cellular junctions.
2. the ability of cells to adhere to a meshwork of proteins and polysaccharides outside the cell called the extracellular matrix.
the _________ of the cytoskeleton provide internal support for cells.
microtubules and microfilaments
All eukaryotic cells have at least two cytoskeletal elements:
long chains made of protein subunits
All of the cytoskeletal elements are
are tubelike structures that are polymers of protein dimers
alpha and beta tubulin
Each dimer is made of two tubulin proteins:
One α tubulin and one β tubulin combine to form a
tubulin dimers assemble to form
are polymers of actin monomers that are arranged into a helix.
are the thinnest of the three cytoskeletal fibers and
are present in various locations in the cytoplasm.
are relatively short and extensively branched just beneath the plasma membrane of a cell.
reinforce the plasma membrane and organize the proteins associated with it.
Microtubules and microfilaments
become longer by the addition of subunits to their ends and shrink by the loss of subunits
Microtubules and microfilaments
Usually, these polymers grow faster at one end than the other.
plus end; minus end
The faster-growing end is called the _____ and the slower-growing end is called the _______
organizing center of the centrosome
In animal cells, the minus ends of microtubules are positioned at the
the plasma membrane.
In animal cells, the plus ends of microtubules project outward toward
The cycles of polymerization (growth) and depolymerization (shrinkage) in microtubules are called
rapid shrinking of microtubules
slower growth of microtubules
dramatic shrinkage is often called ________ and takes place because the plus end of a microtubule is structurally unstable.
________carries cargo, such as vesicles, toward the plus ends of microtubules.
When microtubules and microfilaments are joined by small accessory proteins called ________, they are capable of amazing movement
kinesin and dynein
Two motor proteins
___________ moves the cargo towards the plus end of the microtubule
___________ moves cargo toward the minus end og the microtubule
cilia and flagella
Microtubules are found in _______, which propel the movement of cells or the movement of substances surrounding cells
In cilia and flagella the microtubules associate with the motor protein _______, which causes movement
An _________is a strong fiber composed of intermediate filament proteins.
There are over _____ different kinds of intermediate filaments.
In epithelial cells, the intermediate filament subunits are
In fibroblasts, the intermediate filament are
In neurons, the intermediate filaments are
are intermediate filaments found inside the nucleus, where they support the nuclear envelope.
Many intermediate filaments become attached at the cytoplasmic side of cellular junctions called ___________.
intermediate filaments to cellular junctions (desmosomes)
This anchoring of ____________ provides strong support for the cells, greatly strengthening the epithelial tissue, which allows the skin to withstand the stress it endures daily.
cell adhesion molecules
Cells are attached to one another and to the extracellular matrix by cell-surface proteins called
adherens junctions and desmosomes.
Cadherins are not distributed randomly in the plasma membrane but are located in ________. These complexes anchor cells to one another and are reinforced by the cytoskeleton.
An _________ is a beltlike junctional complex of cadherins that goes around the circumference of the cell.
_________ are buttonlike points of adhesion that hold the plasma membrane of adjacent cells together
Epithelial cells are firmly anchored to the basal lamina by a version of the desmosome called a
______ are the prominent cell adhesion molecules in hemidesmosomes.
Junctional complexes called ____________ establish a seal between cells so that the only way a substance can travel from one side of a sheet of epithelial cells to the other is by moving through the cells by means of one of the cellular transport mechanisms.
Some junctions such as _________ of animal cells and plamodesmata of plant cells are connections between the plasma membranes of adjacent cells that permit materials to pass directly from the cytoplasm of one cell to the cytoplasm of another.
_________ allow plant cells to transfer RNA molecules and proteins because they are much larger than gap junctions.
A _______ is the genetic material of a cell, organism, organelle, or virus, and its sequence is the order of bases along the DNA or (in some viruses) RNA.
Every person's _________ is unique (with the exception of identical twins)
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