Chapter 11- Cell Signaling Flashcards
The stage of cell signaling in which a chemical signal is “detected” when the signaling molecule bind to a receptor protein located at the cell’s surface is called ___________.
Reception
What effect does ligand binding have on receptor tyrosine kinase proteins?
Ligand binding causes them to phosphorylate and form dimers
When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane A2. Thromboxane A2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example thromboxane A2 is acting as a __________. Explain.
Local regulator.
Because of the damaged blood vessel, thromboxane A2 became responsible to heal the injured site.
Second-messengers tend to be water-soluble and small. This accounts for their ability to _______.
rapidly move throughout the cell by diffusion
In liver cells, epinephrine stimulates the breakdown of glycogen. As the signal-transduction pathway progresses, __________.
the signal is amplified
What happens during the process of paracrine signaling?
Numerous cells simultaneously receive and respond to the molecules of growth factor produced by a single cell in their vicinity.
A small molecule that specifically bind to a larger molecule is called a(n) _________.
Ligand
In which part of the cell are calcium ions usually found?
Endoplasmic reticulum
The stage of cell signaling in which the signal is converted to a form that can bring about a response in the cell is called _________.
Trandsduction
Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because __________.
they amplify the original signal manyfold
Evidence that cell signaling evolved early in the history of life comes from _________.
the similarity of the mechanisms in organisms that have a very distant common ancestor
A difference between the mechanisms of cAMP and Ca2+ in signal transduction is that cAMP ________ and Ca2+ _________.
is synthesized by an enzyme in response to a signal; is released from intercellular stores
G-protein-linked receptors _________, whereas receptor tyrosine kinases ________.
are not enzymes; have enzymatic functions
What is the general name for an enzyme that transfers phosphate groups from ATP to other molecules?
Protein kinase
After signaling molecule binds to a G-protein-coupled receptor, what activates the associated G-protein?
GTP displaces GDP on the G-protein
Describe the function of inositol trisphosphate (IP3) as a second messenger?
Inositol trisphosphate bind to an IP3-gated calcium channel, causes the release of calcium ions from the endoplasmic reticulum
In phosphorylation cascade, __________ phosphorylate proteins, and __________ dephosphorylate them.
Protein kinases; protein phosphatases
How is nitric oxide different from other signal molecules?
It is a gas
cAMP usually directly activates _________.
Protein kinase A
A G-protein is active when ….
GTP is bound to it
What did Sutherland discover about glycogen metabolism in liver cells?
The hormone epinephrine binds to a specific receptor on the plasma membrane of the liver cell
What happens to cells undergoing apoptosis?
Cells shrink and form lobes, which are eventually shred as membrane fragments
Describe the process of hormonal signaling
Specialized cells release hormone molecules, which travel via the circulatory system to other parts of the body, where they reach target cells that can recognize and respond to the hormones.
How does adenylyl cyclase help transmit signal within a cell?
It converts ATP to cAMP, which then broadcasts the signal to the rest of the cell.
Ras, a small G-protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably.
A mutation that means Ras cannot hydrolyze GTP to GDP
The process of phosphorylation is very important as a cellular mechanism for regulating protein activity. Phosphorylation does this by __________.
activating or inactivating proteins
IP3 (inositol trisphosphate) is produced as a result of __________.
The cleavage of a certain kind of phospholipid in the plasma membrane
Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence?
Nontarget cells lack the intracellular receptors that, can interact with genes in the cell’s nucleus
Why does testosterone not affect all cell in the body?
Only certain cells have cytoplasmic receptors for testosterone
Certain yeast cells secrete a molecule called the -factor. The purpose of this molecule is to _____________.
stimulate an a yeast cell to grow toward the cell
An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
A.) phosphodiesterase B.) serine/threonine kinases C.) phospholipase C D.) adenylyl cyclase E.) tyrosine kinases
C.) phospholipase C
What are the three stages of the process by which a signal is converted to a specific cellular response?
- ) reception if signaling molecule
- ) transduction of the signal
- ) response to the signal
What molecules are involved in Reception?
- ) G protein-coupled receptor
- ) receptor tyrosine kinase
- ) signaling molecule
What molecules are involved in Transduction?
- ) Phosphorylation cascade
- ) second messenger
- ) adenylyl cyclase
- ) Ca2+
- ) cAMP
- ) IP3
What molecules are involved in Response?
1.) protein synthesis
