Molecular Biology of the Cell Chapter 15 Part 1

A target cell response

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?

Hundreds of different signal molecules

A cell in a multicellular organism is exposed to what?

the original signal

Alteration of effector proteins is necessary for implementing the changes dictated by what?

NO synthase (NOS)

An activated nerve terminal releases acetylcholine, it binds to the receptor on the underlying endothelial cell activating what?

1. Controlling population density and coordinating motility 2. Influencing antibiotic production, spore formation and sexual conjugation

Bacteria respond to chemical signals secreted by their neighbors for what two functions?

A slow response

Besides rapid responses, extracellular signaling molecules can also induce what kind of response within the target cell

A sympathetic nerve to respond to a signal and pass that intracellular response to an adjacent cell that is not innervated

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?

Different combinations of extracellulular signal molecules

Cells have different receptors that allows them to respond to what?

1. Phosphorylation 2. Changes in a proteins subcellular localization 3. Alterations in protein-protein interactions

Changes in protein activity can be induced by what? (three answers)

Events that occur during development and in the immune response

Contact dependent signaling is important for what signaling events?

The amount of gene regulatory proteins activated, and in turn, the pattern of gene expression between cells found along the morphogen gradient will differ

Differences in receptor activation leads to differences in the what?

Different target cell responses

Different cell types can respond to the same signal to induce what?

Different receptors on different target cells

Differential responses are accomplished by the expression of what?

Slow

Endocrine signaling depends on blood flow for delivery therefore signal transmission is what (fast or slow)?

A response in different target cells

Endocrine signaling requires that different endocrine cells secrete different hormones to induce what?

High specificity for a particular hormone

Endocrine signaling requires that the target cell express receptors with what?

Diffusion and blood flow to carry the signaling molecule to the target cells

Endocrine signaling therefore depends on what? To carry what molecule? To what cells?

Extracellular chemical signals

For cells in a multicellular organism to function as an organized group they must be able to recognize, and respond to, what?

Very low concentrations

For endocrine signaling, secreted hormones are diluted in the bloodstream and therefore must be able to function at what concentrations?

Rapid

For signals that induce a change in target cell protein activity, the intracellular response is what (slow or rapid)?

Very high concentration

For synaptic signaling, neurons release their signaling molecule at what concentration (low or very high) into the extracellular matrix adjacent to the target cells?

Gene transcription requiring mRNA processing, mRNA export and then protein synthesis

For these signaling molecules, the target cell response involves changes in what? (three answers)

Nitric Oxide (the gas)

Give an example of a signal molecule that can pass through the target cell's membrane for intracellular receptor binding?

Axonal signaling in neurons

Give an example of synaptic signaling:

1. Proteins 2. Peptides 3. Amino acids 4. Nucleotides

Give some examples of signaling molecules that use cell surface receptors

1. Steroid hormones 2. Retinoids 3. Vitamin D 4. Nitric oxide (NO) 5. Carbon monoxide (CO)

Give some examples of signaling molecules that use intracellular receptors

Long distances

How far are hormones carried to act on target cells (short or long distances)

A: Contact-dependent B: Paracrine C: Synaptic D: Endocrine

Identify the intracellular signaling pathways?

A: Altered metabolism B: Altered gene expression C: Altered cell shape or movement

Identify the products produced by intracellular signaling pathway

A: Extracellular signal molecule B: Receptor protein C: Intracellular signaling proteins D: Effector proteins

Identify the structure/signals of the intracellular signaling pathway

Signaling molecules (hormones)

In endocrine signaling, endocrine cells secrete their what into the bloodstream

Neuronal 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?

Cyclic GMP

In the cytosol, NO binds to its receptor, soluble guanylyl cyclase triggering the enzymatic conversion of GTP to what?

Within different compartments of the cell

Intracellular receptors may reside where?

Directly to the target cell

Long axonal extension make direct contact with a target cell such that chemical signals released are delivered where?

Synaptic and endocrine signaling

Long distance signaling mechanisms include what?

External signals

Most cells in a multicellular organism can release and receive what?

A: Survive B: Divide C: Differentiate D: Die

Multiple extracellular signals illicit what kind of cellular responses?

The cytosol of the smooth muscle cells

NO diffuses out of the endothelial cell and enters what?

Different cell types

Paracrine signaling occurs between the same or different cell types?

The desired target cell response

Rapid intracellular responses to an extracellular signal is seen when changes in cell movement, secretion or metabolism is what?

Specific at very low concentrations

Signal molecule binding to a receptor is highly what and occurs at what kind of concentrations?

Cell survival, growth, division, differentiation and cell death

Signal molecules work together to regulate what basic functions of the cell?

"Autocrine signaling"

Signaling between the same cell types is called what?

Exocytosis

Signaling molecules are released by the signaling cell by what process?

Intracellular mediators such as calcium or cyclic AMP

Signaling pathways that result in the production of what can transmit this signal to a neighboring cell via passage through gap junctions?

Cell-surface receptors

Signals such as proteins, peptides, amino acids, or nucleotides are typically recognized by what?

Pass through the plasma membrane to directly bind to intracellular receptors

Small hydrophobic molecules such as steroid hormones, retinoids, and vitamin D as well as dissolved gases like NO and CO can do what?

The cytosol

Some signal molecules activate intracellular receptors found where in the target cells?

Span the plasma membrane and remain tethered to the signaling cell

Some signaling molecules are transmembrane proteins that do what?

Plasma membrane

Some signaling molecules can directly diffuse through the cell's what?

Only a low affinity

Synaptic signaling receptors on target cells require what kind of affinity (low or high) for the signal ligand?

The method of delivery and the target cells intracellular response to the extracellular signal

Target cell response time to a molecular signal depends on what

On to another protein, which in turn passes it on to another protein in the pathway

The activated intracellular signaling protein passes the signal where?

1. Differences in receptors (heart muscle and skeletal muscle cells) 2. Differences in the intracellular signaling pathway activated (heart muscle and salivary gland cells)

The differences in target cell response when different receptors are bound to acetylcholine may be due to what? (2 answers)

The number of signal-receptor complexes activated

The differential response to morphogen concentration is linked to what?

Metabolism, gene expression, cell shape or cell movement

The end result of activation of intracellular signaling may include changes in what?

Single celled and multicellular organisms

The general molecular organization of a signaling pathway are similar for what organisms?

Transmembrane proteins found in the plasma membrane of target cells

The most familiar signaling receptors are what?

The induction of different sets of genes during development

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 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 what?

'Quorum sensing'

The signaling process which controls density, coordinates motility, influences antibiotic production, spore formation and sexual conjugation is called what in bacteria?

The effector proteins

The terminal target of internal signaling are what?

Delivery method of the signaling molecule [rapid (synaptic signaling) or slow (endocrine signaling)]

The two intracellular response pathways [fast (changes in protein activity) or slow (gene transcription)] are not linked to the what?

A multistep signaling cascade

This pathway includes acetylcholine release by an 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?

The adjacent smooth muscle cells

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?

Gap junctions

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?

A coordinated manner

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?

Arginine

Using what as a substrate NOS generates the gas NO?

Extracellular developmental signals

What are "morphogens"?

B: Decreased rate and force of contraction C: Muscle contraction D: Secretion

What are the responses for the heart muscle (B), skeletal muscle cell (C) and salivary gland cell when their receptors are bound by acetylcholine?

Cell-surface receptors and intracellular receptors

What are two different types of receptors?

Induces smooth muscle relaxation

What does NO do?

The nuclear receptor superfamily (transcription factors)

What is a large family of cytosolic proteins that bind to membrane permeable signals such as steriod hormones, thyroid hormone, retinoids and vitamin D?

Homogenize the cytoplasm of one cell with its neighbor

What is the main function of a gap junction?

Fast (<sec to min)

What is the speed of changes in protein changes in A?

Slow (mins to hours)

What is the speed of changes in protein changes in B?

Gap junction

What is this structure?

Single cells that exist in a community

What kind of cells participate in intracellular communication

Cell-cell communication

What kind of communication includes receptor proteins, intracellular signaling proteins, and effector proteins?

Activated receptors

What kind of receptors undergo a conformational change that transmits the signal to an intracellular signaling protein?

"Paracrine signaling"

What kind of signaling happens when the signaling molecule acts on neighboring cells the process (the signaling molecule is released by the signaling cell) ?

"Contact-dependent signaling"

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?

Endocrine signaling

What kind of signaling is this?

Synaptic signaling

What kind of signaling is this?

Synaptic signaling

What kind of signaling is triggered by an electrical signal and is therefore much faster?

1. Rapid uptake by neighboring cells 2. Degradation by extracellular proteases, 3. Immobilization by extracellular matrix proteins

What mechanisms are used to prevent signal molecule diffusion?

Receptor proteins

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?

1. 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

What three things are necessary for cells in a multicellular organism to be able to recognize and respond to extracellular chemical signals?

Cell-surface receptor

What type of cellular receptor is this?

Intracellular receptor

What type of cellular receptor is this?

A signaling cascade

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?

Upon their activation

When are effector proteins are altered in some way?

Secretion

When the signal molecule acetylcholine is bound to cell surface receptors on slaivary gland cells, it results in what?

Decreased cell contraction,

When the signal molecule acetylcholine is bound to its receptor on a heart muscle, what are the results?

Muscle contraction

When the signal molecule acetylcholine is bound to its receptor on skeletal muscle cells it induces what?

Epithelial cells

Where are gap junctions found?

Target cells closest to the source of morphogen have more activated receptors than target cells furthest from the morphogen source

Which cells have more activated receptors - (the target cells closest to the source of morphogen or the targets furthest away from the source)?

Cytosolic phosphodiesterases

cGMP is rapidly degraded by what?

Muscle relaxation

cGMP then triggers downstream signaling leading to what?