BIO 1200 Chapter 9

Put the steps involved in a signal transduction cascade involving a G-protein-coupled receptor 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 (PKA) is activated 5. Cellular proteins become phosphorylated and cause a cellular response

In the first step of the signal transduction pathway involving cAMP, a signal molecule binds to and activates a receptor called 1._____ . This causes a G protein to bind 2._____ , which promotes the dissociation of the α subunit from the β/γ dimer.

1. GPCR (G-protein-coupled receptor) 2. GTP

Activation of a GPCR causes a G protein to bind 1._____. The activated G protein stimulates adenylyl cyclase to synthesize 2._____ . This second messenger ultimately activates the enzyme 3._____ , which phosphorylates cellular proteins that carry out the cellular response. Listen to the complete question

1. GTP 2. cAMP 3.PKA

The catalytic subunit of 1.______ leads to a cellular response via 2.______ of specific cellular proteins such as enzymes, structural proteins, and transcription factors.

1. PKA 2. Phosphorylation

The five common ways cells communicate with each other are direct intercellular signaling, contact-dependent signaling, 1.____ signaling, 2.____ signaling, and 3.____ signaling.

1. Paracrine 2. Autocrine 3. Endocrine

Put the stages of cell signaling in the correct order.

1. Receptor activation 2. Signal transduction 3. Cellular response

The process of cell signaling consists of three stages: 1.____ activation, signal 2.____ , and a 3.____ response.

1. Receptor activation 2. Signal transduction 3. Cellular response

Cell-to-cell communication can occur via different mechanisms. In 1.____ signaling, a cell can respond to its own signal. In 2.____ signaling, a secreted signaling molecule affects nearby target cells but not the cell that secreted the signal. In 3.____ signaling, the signaling molecule can affect cells at a distance from the cell that secreted the signal.

1. autocrine 2. paracrine 3. endocrine

signal transduction

A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell.

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

A signal transduction pathway

endocrine signaling

A type of long-distance signaling in animals that utilizes hormones. A signaling molecule acts on target cells distant from the cell that secreted the signal.

Apoptosis is an example of what type of response involving cell communication?

Cellular

What type of signaling involves signals that pass through a cell junction from the cytosol of one cell to the cytosol of an adjacent cell?

Direct intercellular signaling

What are examples of cell-to-cell signaling?

Endocrine signaling Contact-dependent signaling Paracrine signaling Direct intercellular signaling Autocrine signaling

True or false: Some living cells do not conduct and require cell communication to survive.

False For living cells to survive, they all need to communicate at the cellular level. This communication is also known as cell signaling.

True or false: A cell that has been stimulated to produce a second messenger continues to produce the second messenger permanently.

False Second messenger signaling is usually of short duration.

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

G protein

What type of receptor mediates the signal transduction pathway associated with cAMP?

G-protein-coupled receptor

Where are cell surface receptors found?

In the plasma membrane

How does EGF released from one cell reach its receptor on another cell?

It travels through the bloodstream.

What type of interaction occurs between a ligand and its receptor?

Non-covalent and specific

During the fourth step in the signal transduction pathway involving cAMP, the phosphorylation of specific cellular proteins by ______ causes a cellular response.

PKA

Cell communication, also called cell ______, involves both incoming and outgoing signals.

Signaling

receptor activation

The "turning on" of a receptor, which often occurs when a signaling molecule binds to a receptor on a responding cell.

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

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

The production of second messengers has been found to have two important advantages in cellular signaling. What are they?

They amplify the original signal. They increase the speed of intracellular signaling.

True or false: The mode of communication between two cells depends in part on the distance between the cells.

True Cells that are adjacent to one another communicate through paracrine signaling and contact-dependent signaling. Cells that are far away from one another communicate using hormones.

True or false: Apoptosis is a process that involves cell communication.

True During apoptosis, cells detect and respond to signals in their environment. Cell signaling or the failure of cell signaling can stimulate apoptosis.

cellular response

adaptation at the cellular level that involves a cell responding to signals in its environment

Cyclic AMP is synthesized by the enzyme _____

adenylyl cyclase

The synthesis of cAMP occurs when one type of G protein α subunit interacts with the enzyme _____

adenylyl cyclase

A synonym for programmed cell death is:

apoptosis

The enzyme adenylyl cyclase, which synthesizes cAMP, is stimulated by:

binding of the α subunit of a G protein

EGF travels through the _____ to bind to EGF receptors.

bloodstream

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

cAMP (cyclic adenosine monophosphate)

The GPCR mediates the signal transduction pathway involving _____ , which is synthesized by activated adenylyl cyclase.

cAMP (cyclic adenosine monophosphate)

The interaction between the α subunit of an appropriate G protein and adenylyl cyclase causes adenylyl cyclase to synthesize:

cAMP (cyclic adenosine monophosphate)

what is an example of a second messenger?

cAMP (cyclic adenosine monophosphate)

second messangers

cAMP and Ca2+ are secondary messangers in signal transduction that interpret the message and trigger the appropriate function of a specific cell (division, secretion, differentiation, metabolism, etc.)

Cell signaling is important because:

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

autocrine signaling

cells respond to signaling substances that they themselves secrete A signaling molecule binds to a receptor on the same cell that secreted the signal.

When ligands alter the structure of their receptors, this causes a(n):

conformational change

The abbreviation cAMP refers to:

cyclic adenosine monophosphate.

Signals passing through a cell junction from the cytosol of one cell to an adjacent cell is a description of:

direct intercellular signaling

Cell signaling allows cells to detect and respond to signals from their ____ and from other cells.

environment

Signaling molecules that bind to a cell surface receptor are considered:

first messengers Second messengers are produced inside the target cell in response to another signal. The original signaling molecule that binds to a cell surface receptor is the first messenger.

A ____ factor is a protein ligand that acts as a signaling molecule that stimulates cell growth or division.

growth factor

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

growth factor

Signaling molecules that promote cell division are called:

growth factors

Second messengers relay signals:

inside the cell

Cellular receptors can be located:

inside the cell on the cell surface

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:

intracellular receptors

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

ligand

contact-dependent signaling

molecules bound to the surface of cells serve as signals to cells coming in contact with them A membrane-bound signaling molecule binds to a receptor on the surface of another cell.

A ligand binds ____ to its receptor with a high degree of specificity.

noncovalently

In signal transduction pathways that are associated with cAMP, protein kinase A uses ATP to _____ specific cellular proteins.

phosphorylate

Cell surface receptors are receptors that are embedded in the:

plasma membrane

Some signaling molecules must pass through the ____ before activating a receptor located in the cytosol or the nucleus.

plasma membrane

First messengers are signaling molecules that bind to cell surface

receptors

First messengers are signaling molecules that bind to cell surface ____

receptors

Proteins that interact with signaling molecules are called _____ . These proteins can be located on the cell surface or inside the cell.

receptors

Small molecules or ions that relay signals inside the cell are called:

second messengers

paracrine signaling

secreted molecules diffuse locally and trigger a response in neighboring cells A signaling molecule affects target cells nearby but not the cell that secreted the signal.

A growth factor is a type of:

signaling molecule

direct intercellular signaling

signals pass through a cell junction from the cytosol of one cell to adjacent cells A signaling molecule passes between the cytosol of adjacent cells through a cell junction.

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

structural proteins transcription factors enzymes

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

the binding of a signaling molecule activates: GPCR the G protein binds to: GTP the α subunit dissociates from: β/γ dimer

The mode of cell communication depends on:

the distance between the cells that need to communicate

first messengers

the extracellular signaling molecule that binds to the cell surface membrane receptor. (such as GPCR's)

The effect of signaling molecules on cells occurs through signal transduction pathways that ultimately control the:

the functions and or synthesis of specific proteins

When a signaling molecule binds to its receptor, it stimulates a signal ____ pathway.

transduction

Signaling molecules exert their effects on cells through signal _____ pathways.

transduction pathways