Chapter 15 Flashcards
For cells in a multicellular organism to function as an organized group they must be able to recognize, and respond to, what?
Extracellular chemical signals
What three things are necessary for cells in a multicellular organism to be able to recognize and respond to extracellular chemical signals?
- Being able to regulate the signals emitted, 2. Having the released signal recognized by the correct ‘receiving’ cell, 3. Having the signal ‘interpreted’ to generate a change in cell behavior
Most cells in a multicellular organism can release and receive what?
External signals
What kind of cells participate in intracellular communication
Single cells that exist in a community
Bacteria respond to chemical signals secreted by their neighbors for what two functions?
- Controlling population density and coordinating motility 2. Influencing antibiotic production, spore formation and sexual conjugation
The signaling process which controls density, coordinates motility, influences antibiotic production, spore formation and sexual conjugation is called what in bacteria?
‘Quorum sensing’
The general molecular organization of a signaling pathway are similar for what organisms?
Single celled and multicellular organisms
What kind of communication includes receptor proteins, intracellular signaling proteins, and effector proteins?
Cell-cell communication
What proteins are often cell surface proteins (several intracellular receptor proteins exist), and are responsible for recognizing the signaling molecule which leads to receptor activation?
Receptor proteins
What kind of receptors undergo a conformational change that transmits the signal to an intracellular signaling protein?
Activated receptors
The activated intracellular signaling protein passes the signal where?
On to another protein, which in turn passes it on to another protein in the pathway
When a signaling protein passes the signal on to another protein, which in turn passes it on establishes a sequence of intracellular signaling events referred to as what?
A signaling cascade
The terminal target of internal signaling are what?
The effector proteins
When are effector proteins are altered in some way?
Upon their activation
Alteration of effector proteins is necessary for implementing the changes dictated by what?
the original signal
The end result of activation of intracellular signaling may include changes in what?
Metabolism, gene expression, cell shape or cell movement
Identify the structure/signals of the intracellular signaling pathway
A: Extracellular signal molecule B: Receptor protein C: Intracellular signaling proteins D: Effector proteins
Identify the products produced by intracellular signaling pathway
A: Altered metabolism B: Altered gene expression C: Altered cell shape or movement
Give some examples of signaling molecules that use cell surface receptors
- Proteins 2. Peptides 3. Amino acids 4. Nucleotides
Give some examples of signaling molecules that use intracellular receptors
- Steroid hormones 2. Retinoids 3. Vitamin D 4. Nitric oxide (NO) 5. Carbon monoxide (CO)
What are two different types of receptors?
Cell-surface receptors and intracellular receptors
Signals such as proteins, peptides, amino acids, or nucleotides are typically recognized by what?
Cell-surface receptors
Small hydrophobic molecules such as steroid hormones, retinoids, and vitamin D as well as dissolved gases like NO and CO can do what?
Pass through the plasma membrane to directly bind to intracellular receptors
Intracellular receptors may reside where?
Within different compartments of the cell
Signal molecule binding to a receptor is highly what and occurs at what kind of concentrations?
Specific at very low concentrations
Signaling molecules are released by the signaling cell by what process?
Exocytosis
Some signaling molecules can directly diffuse through the cell’s what?
Plasma membrane
Some signaling molecules are transmembrane proteins that do what?
Span the plasma membrane and remain tethered to the signaling cell
What type of cellular receptor is this?
Cell-surface receptor
What type of cellular receptor is this?
Intracellular receptor
What kind of signaling is it when the signaling molecule remains bound to the extracellular surface of a signaling cell, direct interaction between the signaling cell and the target cell is required?
Contact-dependent signaling
Contact dependent signaling is important for what signaling events?
Events that occur during development and in the immune response
What kind of signaling happens when the signaling molecule acts on neighboring cells the process (the signaling molecule is released by the signaling cell) ?
Paracrine signaling
Paracrine signaling occurs between the same or different cell types?
Different cell types
Signaling between the same cell types is called what?
Autocrine signaling
What mechanisms are used to prevent signal molecule diffusion?
- Rapid uptake by neighboring cells 2. Degradation by extracellular proteases, 3. Immobilization by extracellular matrix proteins
Long distance signaling mechanisms include what?
Synaptic and endocrine signaling
Give an example of synaptic signaling:
Axonal signaling in neurons
Long axonal extension make direct contact with a target cell such that chemical signals released are delivered where?
Directly to the target cell
In endocrine signaling, endocrine cells secrete their what into the bloodstream
Signaling molecules (hormones)
How far are hormones carried to act on target cells (short or long distances)
Long distances
Endocrine signaling therefore depends on what? To carry what molecule? To what cells?
Diffusion and blood flow to carry the signaling molecule to the target cells
Identify the intracellular signaling pathways?
A: Contact-dependent B: Paracrine C: Synaptic D: Endocrine
Endocrine signaling depends on blood flow for delivery therefore signal transmission is what (fast or slow)?
Slow
What kind of signaling is triggered by an electrical signal and is therefore much faster?
Synaptic signaling
For endocrine signaling, secreted hormones are diluted in the bloodstream and therefore must be able to function at what concentrations?
Very low concentrations
Endocrine signaling requires that the target cell express receptors with what?
High specificity for a particular hormone
For synaptic signaling, neurons release their signaling molecule at what concentration (low or very high) into the extracellular matrix adjacent to the target cells?
Very high concentration
Synaptic signaling receptors on target cells require what kind of affinity (low or high) for the signal ligand?
Only a low affinity
Endocrine signaling requires that different endocrine cells secrete different hormones to induce what?
A response in different target cells
In synaptic signaling, what cells can use the same signaling molecule to trigger a response in different cells because the synaptic terminii delivers the signal to target cell?
Neuronal cells
What kind of signaling is this?
Endocrine signaling
What kind of signaling is this?
Synaptic signaling
Target cell response time to a molecular signal depends on what
The method of delivery and the target cells intracellular response to the extracellular signal
For signals that induce a change in target cell protein activity, the intracellular response is what (slow or rapid)?
Rapid
Changes in protein activity can be induced by what? (three answers)
- Phosphorylation 2. Changes in a proteins subcellular localization 3. Alterations in protein-protein interactions
Rapid intracellular responses to an extracellular signal is seen when changes in cell movement, secretion or metabolism is what?
The desired target cell response
Besides rapid responses, extracellular signaling molecules can also induce what kind of response within the target cell
A slow response
For these signaling molecules, the target cell response involves changes in what? (three answers)
Gene transcription requiring mRNA processing, mRNA export and then protein synthesis
The two intracellular response pathways [fast (changes in protein activity) or slow (gene transcription)] are not linked to the what?
Delivery method of the signaling molecule [rapid (synaptic signaling) or slow (endocrine signaling)]
What is the speed of changes in protein changes in A?
Fast (
What is the speed of changes in protein changes in B?
Slow (mins to hours)
Transmission of an intracellular response to neighboring cells occurs by the passage of inorganic ions or small water soluble molecules through water-filled channels that directly link adjacent cells. What are these water-filled channels?
Gap junctions
Where are gap junctions found?
Epithelial cells
What is the main function of a gap junction?
Homogenize the cytoplasm of one cell with its neighbor
Signaling pathways that result in the production of what can transmit this signal to a neighboring cell via passage through gap junctions?
Intracellular mediators such as calcium or cyclic AMP
Cell-cell communication mechanism using gap junctions allows one cell innervated by what? That respond to what? Pass the reponse where? which is not what?
A sympathetic nerve to respond to a signal and pass that intracellular response to an adjacent cell that is not innervated
Using gap junctions allow cells can respond to extracellular signals in what kind of manner even if not all target cells have bound the signaling molecule?
A coordinated manner
What is this structure?
Gap junction
A cell in a multicellular organism is exposed to what?
Hundreds of different signal molecules
A cell in a multicellular organism is exposed to hundreds of different signal molecules. It is the combinations of these different signals that induce what?
A target cell response
Differential responses are accomplished by the expression of what?
Different receptors on different target cells
Signal molecules work together to regulate what basic functions of the cell?
Cell survival, growth, division, differentiation and cell death
Multiple extracellular signals illicit what kind of cellular responses?
A: Survive B: Divide C: Differentiate D: Die
Cells have different receptors that allows them to respond to what?
Different combinations of extracellulular signal molecules
Different cell types can respond to the same signal to induce what?
Different target cell responses
When the signal molecule acetylcholine is bound to its receptor on a heart muscle, what are the results?
Decreased cell contraction,
When the signal molecule acetylcholine is bound to its receptor on skeletal muscle cells it induces what?
Muscle contraction
When the signal molecule acetylcholine is bound to cell surface receptors on slaivary gland cells, it results in what?
Secretion
The differences in target cell response when different receptors are bound to acetylcholine may be due to what? (2 answers)
- Differences in receptors (heart muscle and skeletal muscle cells) 2. Differences in the intracellular signaling pathway activated (heart muscle and salivary gland cells)
What are the responses for the heart muscle (B), skeletal muscle cell (C) and salivary gland cell when their receptors are bound by acetylcholine?
B: Decreased rate and force of contraction C: Muscle contraction D: Secretion
The same type of target cell can differ in their intracellular response to the same extracellular signal based on what?
The extracellular concentration of the signaling molecule
The same type of target cell can differ in their intracellular response to the same extracellular signal based on the extracellular concentration of the signaling molecule.This differential response is important for what?
The induction of different sets of genes during development
What are “morphogens”?
Extracellular developmental signals
The differential response to morphogen concentration is linked to what?
The number of signal-receptor complexes activated
Which cells have more activated receptors - (the target cells closest to the source of morphogen or the targets furthest away from the source)?
Target cells closest to the source of morphogen have more activated receptors than target cells furthest from the morphogen source
Differences in receptor activation leads to differences in the what?
The amount of gene regulatory proteins activated, and in turn, the pattern of gene expression between cells found along the morphogen gradient will differ
The most familiar signaling receptors are what?
Transmembrane proteins found in the plasma membrane of target cells
Some signal molecules activate intracellular receptors found where in the target cells?
The cytosol
Give an example of a signal molecule that can pass through the target cell’s membrane for intracellular receptor binding?
Nitric Oxide (the gas)
What does NO do?
Induces smooth muscle relaxation
This pathway includes acetylcholine release by an
A multistep signaling cascade
http://o.quizlet.com/FFyv8LmA2bayzHpxqXzd9g.png
activated neuronal cell as the primary signal molecule triggering an intracellular response in the endothelial cells that line the interior of a blood vessel. What kind of pathway is it?
This target cell then becomes the signal cell which releases a signal molecule for the activation of the next target cell in the pathway, what are they?
The adjacent smooth muscle cells
An activated nerve terminal releases acetylcholine, it binds to the receptor on the underlying endothelial cell activating what?
NO synthase (NOS)
Using what as a substrate NOS generates the gas NO?
Arginine
NO diffuses out of the endothelial cell and enters what?
The cytosol of the smooth muscle cells
In the cytosol, NO binds to its receptor, soluble guanylyl cyclase triggering the enzymatic
Cyclic GMP
http://o.quizlet.com/uAJm-7kK3PTW88OhD-8TuQ.png
conversion of GTP to what?
cGMP then triggers downstream signaling leading to what?
Muscle relaxation
cGMP is rapidly degraded by what?
Cytosolic phosphodiesterases
What is a large family of cytosolic proteins that bind to membrane permeable signals such as steriod hormones, thyroid hormone, retinoids and vitamin D?
The nuclear receptor superfamily (transcription factors)
With ligand binding these receptor proteins do what? (4 answers)
- Lose their bound inhibitory proteins 2. Undergo a change in conformation promoting coactivator 3. Protein binding 4. Trigger a change in target gene transcription
For some cytosolic localized nuclear receptor family members, ligand binding results in their movement where? For what purpose?
Translocation into the nucleus for DNA binding
For other receptor proteins ligand binding prevents what from happening to the DNA?
DNA transcription
In all cases, nuclear receptor superfamily members act as what? Give two functions
Both intracellular receptors for signal molecule binding and effectors for the signal
Of the 48 different nuclear receptor family members identified in the human genome; how many have identified ligands?
Only half have identified ligands
What are nuclear receptors with unknown ligands?
‘Orphan’ nuclear receptors
Is this an active receptor or an inactive receptor?
Inactive receptor
Is this an active receptor or an inactive receptor?
Active receptor
For nuclear receptor proteins that activate gene transcription upon ligand binding, the genes that are directly activated constitute what?
The primary response
The primary response proteins can then act to activate the transcription of a second set of genes generating a delayed response to the signal molecule which is referred to as a what?
A secondary-response
The primary response gene products can turn off the primary-response genes, acting as a what? To limit what?
Negative regulatory loop to limit the response of the initial signal
Many cells express the same set of nuclear receptors however the cellular response they induce will vary from cell type to cell type as gene transcription is regulated by what?
A combination of transcription factors which are cell type specific
What type of response is this (primary or secondary)?
Primary response
What type of response is this (primary or secondary)?
Secondary response
What is the process by which cell surface receptor proteins convert extracellular signals into an intracellular one.
Signal transduction
What are the three general classes of cell surface receptors?
- Ion channel coupled receptors 2. G-protein coupled receptors 3. Enzyme couple receptors
What type of receptor is this? 1. It consists of multipass transmembrane proteins 2. It is opened or closed by the binding of neurotransmitters triggering ion permeability across the plasma membrane 3. It is involved in the synaptic signaling between nerve cells and target cells (muscle or nerve cells)
Ion channel coupled receptor
What type of receptor is this? 1. It consists of multipass transmembrane proteins 2. It is responsible for the indirect activation of a plasma membrane bound enzyme or ion channel via the activation of an intermediary heterotrimeric GTP binding protein complex 3. Activation leads to changes in the concentration of small intracellular mediates or plasma membrane permeability
G protein coupled receptor
What type of receptor is this? 1. It is often single pass transmembrane proteins 2. It functions directly as enzymes (left panel in C) or associates with enzymes that they activate (right panel in C) 3. Signal molecule binding to the extracellular domain of the protein triggers dimerization resulting in protein kinase activation which is responsible for phosphorylating specific sets of proteins in the target cell that they activate
Enzyme coupled receptors
What kind of coupled receptor is this?
G- Protein