Chaper 11 Cell-Cell

put the steps of process of signal transduction in the order they occur: 1. A conformational change in the signal-receptor complex activates an enzyme 2. Protein kinases are activated 3. A signal molecule binds to a receptor 4. Target proteins are phosphorylated 5. Second messenger molecules are released

3,1,5,2,4

Which component is a protein fiber of the extracellular matrix?

A

Pemphings vulgaris is an autoimmune disorder in humans in which antibodies are produced against cadherins of desmosomes. The bistering of the skin and mucous membranes characteristic of this disorder is probably a result of ________.

A loss in cell-cell adhesion

which of the following statements is false?

A plant cell continues growing after secondary cell wall froms but stops growing with the formation of the tertiary cell wall

Different body cells can respond differently to the same peptide hormones because____

A target cell's response is determined by the components of its signal transduction pathways

When yeast cells of the "a" mating type are exposed to a solution of "a pheromones

G proteins will be activated in the cell signaling pathway and the yeast cells will change shape

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Glycogen breakdown was observed only when epinephrine was administered to intact cells

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its_______.

Golgi apparatus and extracellular matrix

Where would you expect to find tight junctions?

In the epithelium of an animal's stomach

what is the major difference between the Extracellular matrix of a plant cell and the ECM of an animal cell?

Plan ECM is primarily carbohydrate in nature, whereas animal ECM is mainly proteins

One characteristic of life and living systems is that they are able to adapt. In general, cells interact with other cells and their environment through the action of their

Plasma membrane and extracellular matrix

Acetylcholine is a neurotransmitter that binds to receptors on skeletal muscle cells. The receptor-signal complex brings about a series of events that result in contraction of skeletal muscle. Venom from black widow spiders causes an explosive release of acetlycholine. What would that do to its victims?

The victims muscles would be unable to relax

What do the cell walls of plants and the extracellular matrix of animal cells have in common?

They have functional connections with the cytoskeleton inside the cell

Not all intercelullar signals require transduction. Which one of the following signals would be processed without transduction?

a lipid-soluble signal

When yeast cells of opposite mating types are in close prosimity, cell changes occur inside those cells that resut in the polymerization of actin filaments, allowing the yeast cells to mate. Those changes in cell behavior are initially due to signaling molecules (phreomones) released by the yeast cells. Pheromones are

a type of hormone that binds cell surface receptors causing cytoplasmic actin proteins to form filaments

All of the following proteins may be found in the extracelullar matric of animal cells EXCEPT

actin

protein kinase is an enzyme that

activates or inactivates other proteins by adding a phosphate group processes

Plasmodesmata are cell-cell junctions that are found between

adjacent plants

in plant cells, the middle lamella

allows adjacent cells to adhere to one another

phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they_______.

amplify the original signal many times

Steroid hormones bind to receptors inside the cell and alter their conformation. The hormone-receptor complex is then transported into the nucleus, where it can directly affect gene expression. To get from the location where the receptor binds the hormone to its site of action, the hormone-receptor complex must ____.

be transported through the nuclear pore complex

Consider this pathway: epinephrine ---> G protein----> coupled receptor----> G protein---> adenylyl cyclase---> cAMP. The second messenger in this pathway is

cAMP

which of the following would you NOT find in a plant cell

collagen

Integrins are integral membrane proteins. They are often attached to

cytoskeletal proteins and proteins in the extracelullar matrix

the activation of receptor tyrosine kinases is characterized by

dimerization and phosphorylation

Forms of the Ras protein found in tumors usually cause which of the following?

excessive cell division

Plasmodestata in plant cells are most similar in function to which of the following structures in animal cells?

gap junctions

ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through ___________.

gap junctions

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must ________.

have receptors that recognize and bind the hormone molecule

in signal transduction, phosphatases_____.

inactivate protein kinases and turn off the signal transduction

Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. For this to happen there must be direct communication between the extracellular matrix and the developing cells. Which kinds of trashmembrane protein would most likely be involved in this kind of induction?

integrins

Signals from the extracellular matrix to the cystoskeleton may be transmitted by

integrins

Which of the following is characteristic of a steroid hormone action?

internal receptor binding

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells bu affect only target cells because____________.

intracellular receptors are present only in target cells

which of the foll. statements about quorum sensing is FALSE? Quorum sensing ____

is cell-cell communication in eukaryoes

A G-protein receptor with GTP bound to ti _________

is in its active state

Scaffolding proteins are

large molecules to which several relay proteins attach to facilitate cascade effects

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundadance between and among osteocytes. The collagen and calcium salts are __________.

part of the extracellular matrix

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay protein. Which type does this?

receptor tyrosine kinases

the cancer-causing forms of the Ras protein are involved in which of the following processes?

relaying a signal from a growth factor receptor

In general, a signal transmitted via phosphorylation of a series of proteins

results in a a conformational change to each protein

A gap junction is a channel that connects adjacent cells. Which one of the following cannot pass through a gap junction?

ribosomes

The receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. This is not a problem for steroids because

steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane

a cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's

target cell

What does it mean to say that a signal is transduced?

the physical form of the signal changes from one form to another

For a tissue or an organ to function as a unit, _______.

there must be cell-cell communication among the cells within a tissue or organ

Intercalated discs are cell-cell junctions found btwn cardiac muscle cells. One feature of these intercalated discs is that they contain a large number of gap junctions, which means that ____

water ions and small molecules can readily pass from one cardiac muscle cells to the next gap junction