cell1010 ch9 learnsmart

autocrine, paracrine, endocrine

*Cell-to-cell communication can occur via different mechanisms. In ___ signaling, a cell can respond to its own signal. In ___ signaling, a secreted signaling molecule affects nearby target cells but not the cell that secreted the signal. In ___ signaling, the signaling molecule can affect cells at a distance from the cell that secreted the signal.

cAMP

*During the second step in the signal transduction pathway involving cAMP, the binding of the a subunit to adenylyl cyclase promotes the synthesis of ___ from ATP.

GPCR - Ligand dissociates G protein - GTP is hydrolyzed to GDP cAMP - Broken down by phosphodiesterase Protein kinase A - Inhibited as cAMP levels fall Cellular proteins - Phosphate groups are removed by phosphatases

*Match each component of a GPCR signaling pathway with the event that deactivates it.

EGF receptor - Binding of EGF Ras - Binding of GTP MAP-kinases - Phosphorylation Genes encoding proteins for cell division - Activated transcription factors

*Match each component of the EGF signal transduction pathway with the event that activates it.

1. A ligand binds to a GPCR. 2. A G protein is activated. 3. Phospholipase C is activated. 4. Ca2+ is released from the ER. 5. Protein kinase C is activated.

*Put the steps involved in a signal transduction pathway involving the second messengers DAG and IP3 in the correct order.

phospholipase C

*What enzyme produces diacylglycerol and inositol triphosphate?

-Adenylyl cyclase synthesizes cAMP from ATP. -The G protein activates adenylyl cyclase.

*What happens after activation of a G protein by a GPCR?

inositol triphosphate, diacylglycerol

*What second messengers are produced by phospholipase C?

-The ligand must dissociate from the GPCR. -cAMP must be broken down to AMP. -The G protein must hydrolyze GTP to GDP.

*Which of the following events must occur to reverse the activation of a G-protein-coupled receptor?

signaling molecule

A growth factor is a type of:

GTP; cAMP; PKA

Activation of a GPCR causes a G protein to bind ___. The activated G protein stimulates adenylyl cyclase to synthesize ___. This second messenger ultimately activates the enzyme ___, which phosphorylates cellular proteins that carry out the cellular response.

dimerize; phosphorylating

After EGF binds to its receptors, two receptor molecules ___ and then activate each other by ___ tyrosines within the receptors.

kinase; transcription

After EGP activates its receptor, the signal is transduced to relay proteins that activate a protein ___ casade. This eventually leads to the activation of ___ factors that stimulate the expression of specific genes.

G protein

Binding of the a subunit of a(n) ___ ___ stimulates the enzyme adenylyl cyclase to synthesize cAMP.

-cells need to communicate with each other -cells need to respond to a changing environment

Cell signaling is important because:

second

Cells can use different types of ___ messengers in response to extracellular signals.

autocrine signaling

Cells releasing signals that affect themselves and nearby target cells occurs in:

inside the cell, on the cell surface

Cellular receptors can be located:

receptor

Cellular signaling involves an interaction between a signaling molecule from one cell and a(n) ___ on or in another cell.

adenylyl cyclase

Cyclic AMP is synthesized by:

contact

During ___ dependent signaling, membrane-bound signals bind to receptors on adjacent cells.

paracrine

In ___ signaling, a cell secretes a signaling molecule that does not affect the cell secreting the signal but influences the behavior of target cells in close proximity.

proteins

In hormone signaling, the variation in a cellular response is determined by the types of ___ that each cell type makes.

intracellular receptors

In some cases, a signaling molecule must first pass through the plasma membrane before activating a receptor. The receptors activated by these molecules are called:

ions

Ion channels are proteins that permit ___ to diffuse across cell membranes.

ions

Ligand-gated ion channels ___ to pass through the plasma membrane.

i. Receptor Activation = A signaling molecule binds to a receptor. ii. Signal Transduction = The signal is converted to a different type of signal, often resulting in the production of an intracellular signaling molecule. iii. Cellular Response = An enzyme, structural protein, or transcription factor is altered.

Match each step of cell-to-cell signaling with the appropriate description.

Direct intercellular signaling = A signaling molecule passes between the cytosol of adjacent cells through a cell junction Contact-dependent signaling = A membrane-bound signaling molecule binds to a receptor on the surface of another cell. Autocrine signaling = A signaling molecule binds to a receptor on the same cell that secreted the signal. Paracrine signaling = A signaling molecule affects target cells nearby but not the cell that secreted the signal. Endocrine signaling = A signaling molecule acts on target cells distant from the cell that secreted the signal.

Match each type of cellular communication with the proper description.

Enzyme-linked receptor = The receptor phosphorylates itself or another protein. G-protein-coupled receptor = An intracellular G protein releases GDP and binds to GTP. Ligand-gated ion channel = Ions move across the plasma membrane of the cell. Steroid hormone receptor = The receptor binds to DNA and activates the transcription of specific genes.

Match each type of receptor with the event that occurs after a ligand binds to it.

growth factor

Name the protein ligand that acts as a signaling molecule that stimulates cell division.

1. A signaling molecule binds to a GPCR. 2. The GPCR binds to a G protein. 3. The G protein exchanges GDP for GTP. 4. The G protein subunits dissociate.

Put the events that occur during the activation of a G-protein-coupled receptor in the correct order, beginning with the first event at the top.

1. receptor activation 2. signal transduction 3. cellular response

Put the stages of cell signaling in the correct order.

1. A ligand binds to a G-protein-coupled receptor. 2. An intracellular G protein binds to GTP. 3. Adenylyl cyclase synthesizes cAMP. 4. Protein kinase A is activated. 5. Cellular proteins become phosphorylated and cause a cellular response.

Put the steps involved in a signal transduction cascade involving a G-protein-coupled receptor in the correct order.

1. A ligand binds to its GPCR. 2. A G protein is activated. 3. Phospholipase C is activated. 4. A covalent bond in a phospholipid is broken.

Put the steps involved in the synthesis of diacylglycerol and inositol triphosphate in the correct order.

1. The EGF receptor binds to EGF, dimerizes, and becomes phosphorylated. 2. Relay proteins become activated. 3. Ras releases GDP and binds GTP. 4. A protein kinase cascade becomes activated. 5. Transcription factors become phosphorylated. 6. Genes encoding proteins that promote cell division are expressed.

Put the steps of the signal transduction pathway activated by EGF in the correct order.

short

Second messenger signaling is typically of ___ duration.

diffuse through the cytosol rapidly

Second messengers increase the speed of cellular signaling because they:

-animal cells moving during embryonic development -an amoeba moving towards food

Select all of the following that are the result of cell signaling causing the rearrangement of actin filaments, which are structural proteins.

-protein kinase cascade -transcription factors -relay proteins

Select the three parts of the signal transduction pathway for epidermal growth factor (EGF).

transcription factors, protein kinase cascade, relay proteins

Select the three parts of the signal transduction pathway for epidermal growth factor (EGF).

G-protein-coupled receptor

The binding of a signal molecule to a ___ leads to activation of adenylyl cyclase. The resulting increase in cAMP activates PKA, which phosphorylates specific cellular proteins to cause a cellular response.

-interpreting signals -sending signals -receiving signals

The cellular level of communication involves:

amplify; speed

The main advantage of second messengers in cellular signaling are that they ___ the original signal and increase the ___ of intracellular signaling.

the distance between the cells that need to communicate

The mode of cell communication depends on:

transcription factors, structural proteins

The specific cellular proteins phosphorylated by the catalytic subunit of PKA are:

G-protein-coupled receptors, enzyme-linked receptors, ligand-gated ion receptors

The three categories of cell surface receptors are:

-DAG and IP3 -cAMP

Various GPCRs can stimulate the production of:

A signal transduction pathway

What does the binding of a signaling molecule to its receptor stimulate?

cellular response

What does the interaction between a signal and its receptor elicit?

-They may activate different intracellular signal transduction pathways in response to the same signal. -They may have different receptors for the same signaling molecule. -They may express different proteins controlled by signal transduction pathways.

What enables different cell types to respond to the same hormone in a different way?

proteins

What forms a signal transduction pathway?

the binding of a signaling molecule activates - GPCR the G protein binds to - GTP the a subunit dissociates from - B/y dimer

What happens during the first step in the signal transduction pathway involving cAMP?

receptor activation

What is the first step in cell signaling?

They add phosphate groups to proteins.

What is the function of protein kinases?

G proteins

What proteins can bind to GTP and GDP?

enzyme-linked receptor

What type of receptor functions as a protein kinase?

receptor tyrosine kinase

What type of receptor is the EGF receptor?

Kd

What value represents the concentration of a ligand at which half of the receptors have bound ligand?

ligand

When a signaling molecule binds to a(n) ___-gated ion channel, the channel opens and allows the flow of ions through the membrane.

ligand

When a(n) ___ binds to its receptor, it causes a conformational change in the receptor.

-contact-dependent signaling -direct intercellular signaling -endocrine signaling -paracrine signaling

Which of the following are examples of cell-to-cell signaling?

-IP3 -Ca2+ -DAG -cAMP

Which of the following are used as intracellular second messengers?

G

___ proteins are intracellular proteins that interact with G-protein-coupled receptors.