Biology Chapter 11

Small channels that form across the plasma membranes of adjacent cells; especially important in intercellular communication.

Gap Junctions- animal cells

Put the following steps of cell signaling in the correct order: 1. the secondary messengers elicit a cellular response 2. the signal is transduced and converted to an intracellular response 3. signaling cell produces and releases a signaling molecule 4. receptor molecule on a target cell detects the chemical

3, 4, 2, 1

True or false: There is a 1:1 ration of primary and secondary messengers.

False

A polysaccharide that is used the synthesize cell walls, which protect cells and help maintain their shape.

Cellulose- plant cells

Long fibers of protein found in the extracellular matrix that provide structural support for cells.

Collagen- animal

Membrane protein complexes that strengthen the adhesion between adjacent cells, like rivets, to protect against pulling forces.

Desmosomes- animal cells

True or false: Membrane receptors are only found in the plasma membrane.

False

Small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between cells.

Plasmodesmata- plant cells

Membrane proteins that create a watertight seal between cells.

Tight Junctions- animal cells

Put the steps of the 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. a. 3, 1, 5, 2 and 4 b. 3, 1, 2, 4 and 5 c. 1, 2, 3, 4 and 5 d. 1, 2, 5, 3 and 4

a. 3, 1, 5, 2 and 4

In the case of GPCRs, when G-protein is bound to ______, the synthesis of the second messenger __________. a. GTP; occurs b. GTP; does not occur c. GDP; occurs d. All of the above

a. GTP; occurs

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? a. Receptor tyrosine kinases b. G-protein-coupled receptors c. Ligand-gated ion channels d. steroid receptors

a. Receptor tyrosine kinases

What can be an effect of a signaling molecule binding to a receptor? a. a change in gene expression b. a decrease in second messengers c. a decrease in signal transduction d. all of the above

a. a change in gene expression

All of the following proteins may be found in the extracellular matrix of animal cells EXCEPT ______. a. actin b. proteoglycan c. collagen d. all of the listed proteins are found in the extracellular matrix of animal cells

a. actin

Cadherins: a. are integral membrane proteins found in desmosomes b. form gap junctions c. are found inside of plasmodesmata d. are a type of proteoglycans

a. are integral membrane proteins found in desmosomes

Why is it important for signal-transduction systems to trigger a rapid response within a cell and be able to shut down quickly? a. cells often have to respond very quickly to changes in their internal and external environments b. all signal-transduction cascades are shut down immediately so as to prevent the cell from mounting a response c. cells must be able to function alone because they are unable to work together in a coordinated fashion d. cells are unable to respond quickly to hormones, and therefore signal-transduction cascades always occur over a long time

a. cells often have to respond very quickly to changes in their internal and external environments

Which of the following would you NOT find in a plant cell? a. collagen b. lignin c. polysaccharides d. pectin

a. collagen

The primary role of ______ is to bind animal cells together. a. desmosomes b. tight junctions c. plasmodesmata d. the cytoskeleton e. gap junctions

a. desmosomes

In _______ signaling, _______ act on distantly located cells. a. endocrine; hormones b. paracrine; hormones c. neuronal; neutransmitters d. autocrine; neurohormones

a. endocrine; hormones

Gap junctions: a. form a channel where ions can diffuse between two cells b. are destroyed by a toxin produced by bacteria to cause Staphylococcal Scalded Skin Syndrome c. connect the cytoplasm of adjacent cells in plants and are large enough to allow organelles to pass through d. forms a water tight seal between epithelial cells

a. form a channel where ions can diffuse between two cells

Where would you expect to find tight junctions? a. in the epithelium of an animal's stomach b. in the plasma membrane of prokaryotes c. between plant cells in a woody plant d. between the smooth endoplasmic reticulum and the rough endoplasmic reticulum

a. in the epithelium of an animal's stomach

Which of the following is NOT a method of signal amplification? a. integral membrane protein degradation b. G-protein coupled receptors c. ligand-gated ion channels d. enzyme-linked receptors

a. integral membrane protein degradation

Thyroid hormones bind to ______ receptors. a. intracellular b. plasma membrane ion-channel c. tyrosine-kinase d. steroid e. G-protein-linked

a. intracellular

If an enzyme linked receptor is active, then: a. its receptors are dimerized b. its monomers are being degraded c. the G-protein moves to an enzyme and activates it d. the receptors are cross-oxidized

a. its receptors are dimerized

A signal molecule is also known as a(n): a. ligand b. protein c. initiator d. receptor e. key

a. ligand

A gap junction is a channel that connects adjacent cells. Which one of the following cannot pass through a gap junction? a. ribosomes b. amino acids c. nucleotides d. ions that can regulate heartbeat

a. ribosomes

The process by which a signal of presence of a chemical messenger is converted to an intracellular signal is called: a. signal transduction b. signal transformation c. processing transformation d. cellular activation

a. signal transduction

A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's ______. a. target cell b. secretory cell c. regulatory cell d. plasma cell e. endocrine cell

a. target cell

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 acetylcholine. What would that do to its victims? a. the victim's muscles would be unable to relax b. the victim's cell receptors would be able to bind regulatory hormones but at a rate greatly exceeding normal rates c. the victim's cell receptors would no longer be able to bind regulatory hormones d. the victim's muscles would be unable to contract

a. the victim's muscles would be unable to relax

Signal reception is when: a. a signaling molecule releases a hormone or neurotransmitter b. a chemical messenger binds to a receptor c. the signaling molecule's presence is transduced

b. a chemical messenger binds to a receptor

Pemphigus vulgaris is an autoimmune disorder in humans in which antibodies are produced against the cadherins of desmosomes. The blistering of the skin and mucous membranes characteristic of this disorder is probably a result of ______. a. an inadequate number of G-protein receptors b. a loss in cell-cell adhesion c. inadequate production of cytoskeletal proteins d. a decrease in flexibility of the cell membrane

b. a loss in cell-cell adhesion

Different body cells can respond differently to the same peptide hormones because _______. a. different target cells have different sets of genes b. a target cell's response is determined by the components of its signal transduction pathways c. the hormone is chemically altered in different ways as it travels through the circulatory system d. the circulatory system regulates responses to hormones by routing the hormones to specific targets e. each cell converts that hormone to a different metabolite

b. a target cell's response is determined by the components of its signal transduction pathways

Protein kinase is an enzyme that ______. a. functions as a second messenger molecule b. activates or inactivates other proteins by adding a phosphate group to them c. serves as a receptor for various signal molecule d. produces second messenger molecules

b. activates or inactivates other proteins by adding a phosphate group to them

Consider this pathway: epinephrine --> G-protein-coupled receptor --> G-protein --> adenylyl cyclase -->cAMP. The second messenger in this pathway is ______. a. G-protein- coupled receptor b. cAMP c. adenylyl cyclase d. GTP e. G-protein

b. cAMP

Which of these is NOT correct? a. kinases are enzymes that phosphorylate other molecules b. Cyclic AMP binds to calmodulin c. tyrosine-kinase receptors consist of two polypeptides that join when activated by a signal molecule d. Ion channel are found on both the plasma membrane and the endoplasmic reticulum e. phospholipase C catalyzes the formation of IP3

b. cyclic AMP binds to calmodulin

Which type of cell adhesion is useful for anchoring cells together and defending against sheer forces on tissues? a. gap junction b. desmosome c. selective adhesion d. tight junction

b. desmosome

A G-protein becomes inactive: a. by the action of a phospholipase b. due to the GTPase activity inherent in the G protein c. when cAMP binds to the G protein d. due to the phosphodiesterase activity

b. due to the GTPase activity inherent in the G protein

Estradiol, a female sex hormone released by mice, is suggested to have a neuroprotective effect on memory. Estradiol traveling to the brain is an example of: a. neurotransmitter signaling b. endocrine signaling c. neuroendocrine signaling d. autocrine signaling

b. endocrine signaling

Calcium ions that act as second messengers are stored in _____. a. peroxisomes b. endoplasmic reticula c. lysosomes d. mitochondria e. chloroplasts

b. endoplasmic reticula

Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor? a. cellulose b. estrogen c. glucose d. starch e. glycerol

b. estrogen

Because cell walls consist of cross-linked network of long filaments embedded in a stiff surrounding material, they can be called ______. a. spot-welded sheets b. fiber composites c. plasma membranes d. spongy bone

b. fiber composites

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through ______. a. plasmodesmata b. gap junctions c. desmosomes d. intermediate filaments e. tight junctions

b. gap junctions

A(n) ______ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off. a. protein b. steroid c. carbohydrate d. nucleic acid e. ion

b. steroid

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 _______. a. steroids do not directly affect the cells but instead alter the chemistry of blood plasma b. steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane c. steroids must first bond to a steroid activator, forming a complex that then binds to the cell surface d. the receptors can be readily stimulated to exit and relocate on the membrane surface

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

Which of these cell junctions form a barrier to the passage of materials? a. plasmodesmata b. tight junctions c. desmosomes d. keratin fibers e. gap junctions

b. tight junctions

Intercalated discs are cell-cell junctions found between cardiac muscle cells. One feature of these intercalated discs is that they contain a large number of gap junctions, which means that ______. a. cardiac cells can function independently when necessary b. water ions and small molecules can readily pass from one cardiac muscle to the next c. an extension of smooth ER goes through the gap junction, making it continuous from one cardiac muscle cell to the next d. RNA from one cardiac muscle cell can be transported into an adjacent cell through the gap junction

b. water ions and small molecules can readily pass from one cardiac muscle cell to the next

In an ion channel coupled receptor, a. a g-protein binds to the receptor and turns it on b. an ion binds to the receptor and turns it on c. a ligand binds to the receptor and opens/closes the channel d. an ion couples with the receptor when it is activated

c. a ligand binds to the receptor and opens/closes the channel

Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction? a. a signal that binds to a receptor in the cell membrane b. a signal that binds to the ECM c. a lipid-soluble signal d. a signal that is weakly bound to a nucleotide

c. a lipid-soluble signal

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they _______. a. use a small and fixed number of molecules b. counter the harmful effects of phosphatases c. amplify the original signal many times d. always lead to the same cellular response e. are species specific

c. amplify the original signal many times

The most abundant protein found in the extracellular matrix of _____ cells is collagen. a. bacterial b. plant c. animal d. archaeal

c. animal

If a chemical signaling molecule is lipid soluble, then it: a. uses a membrane associated receptor b. uses a channel protein to enter the cell c. binds directly to internal cytoplasmic receptors d. are impermeable to the plasma membrane

c. binds directly to internal cytoplasmic receptors

The activation of receptor tyrosine kinases are characterized by ______. a. channel protein shape change b. a phosphorylation cascade c. dimerization and phosphorylation d. GTP hydrolysis e. dimerization and IP3 binding

c. dimerization and phosphorylation

_______ aid in the coordination of the activities of adjacent animals cells. a. tight junctions b. plasmodesmata c. gap junctions d. desmosomes e. keratin fibers

c. gap junctions

Lipid insoluble signals would NOT bind to: a. GPCR b. enzyme linked receptors c. internal cytoplasmic receptor d. ion channel coupled receptor

c. internal cytoplasmic receptor

________ can be found between the primary cell walls of adjacent plant cells. a. secondary cell walls b. desmosomes c. middle lamella d. tight junctions

c. middle lamella

Which of the following connect the cytoplasm between two plant cells? a. middle lamella b. cellulose microfibrils c. plasmodesmata d. tight junctions

c. plasmodesmata

Receptor-tyrosine kinases: a. are an example of GPCRs b. are inactivated upon dimerization c. undergo autophosphorylation when they become active d. when activated, a pore in the enzyme opens to transport ions

c. undergo autophosphorylation when they become active

Enzyme-coupled receptors: a. function as dimers b. possess catalytic activity c. undergo autophosphorylation upon activation d. All of the above are true

d. All of the above are true

A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to ____ receptors. a. steroid b. intracellular c. ion-channel d. G-protein-linked e. receptor tyrosine kinase

d. G-protein-linked

Epinephrine acts as a signal molecule that attaches to ______ proteins. a. nuclear receptor b. intracellular receptor c. receptor tyrosine kinase d. G-protein-linked receptor e. ion-channel receptor

d. G-protein-linked receptor

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its _______. a. nuclear matrix and extracellular matrix b. nuclear lamina and nuclear matrix c. nuclear pores and secretory vesicles d. Golgi apparatus and extracellular matrix e. mitochondria and Golgi apparatus

d. Golgi apparatus and extracellular matrix

Which of the following can be an example of a cellular signaling molecule? a. peptide b. amino acid c. nucleotide d. all of the above

d. all of the above

Cell signaling that occurs through a GPCR involves a(n): a. 7-pass transmembrane protein b. G-protein c. an enzyme d. all of the above are true e. only B and C are true

d. all of the above are true

Which of the following is a property of second messenger molecules? a. they typically operate inside the cell b. they are small molecules and can be produced quickly c. they diffuse rapidly throughout the cell to control diverse pathways d. all of the above are true

d. all of the above are true

Which of the following is an example of signal transduction? a. a ligand binding to a membrane-bound receptor causes conformational change in the receptor b. conformational changes in a membrane-bound receptor activate an intracellular signaling molecule c. radio signals being converted to sound waves by a cellphone d. all of the above are true

d. all of the above are true

A protein kinase activating many other protein kinases is an example of _____. a. sensitization b. a cellular response c. mutualism d. amplification e. deactivation

d. amplification

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 ________. a. undergo another conformational change b. enter the smooth ER c. become water soluble by binding to a carrier molecule d. be transported through the nuclear pore complex

d. be transported through the nuclear pore complex

What role does a transcription factor play in a signal transduction pathway? a. by binding to a plasma membrane receptor it initiates a cascade b. it relays a signal from the cytoplasm to the plasma membrane c. it activates relay protein d. by binding to DNA it triggers the transcription of a specific gene e. it is a plasma membrane protein that binds signal molecules

d. by binding to DNA it triggers the transcription of a specific gene

Blood sugar is regulated by two pancreatic hormones—insulin and glucagon. When blood sugar rises, insulin is released; it binds to receptors and, through signal transduction, results in an increase in glucose uptake by cells, which effectively lowers blood glucose levels. When blood sugar decreases, glucagon is released, binds to cell receptors, and causes glucose to be released into circulation, thereby increasing blood glucose levels. Diabetes mellitus is a disorder that results from excessively high levels of blood glucose. Type II diabetics have normal to elevated levels of insulin. What, then, might be causing their elevated blood glucose levels? a. inadequate insulin production b. defective second messenger c. overproduction of glucagon d. defective receptors

d. defective receptors

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many affects. a. estrogen is kept away from the surface of any cells not able to bind it at the surface b. cells metabolize steroids in different ways, producing by-products that stimulate tRNA production c. each cell responds in the same way when steroids bind to the cell surface d. estrogen binds to specific receptors inside many kinds of cells, each with different responses e. estrogen is produced in very large concentration by nearly every tissue of the body

d. estrogen binds to specific receptors inside many kinds of cells, each with different responses

The cleavage of glycogen by glycogen phosphorylase releases _______. a. fructose-1-phosphate b. galactose-1-phosphate c. cellulose d. glucose-1-phosphate e. nothing: glycogen phosphorylase cannot cleave glycogen

d. glucose-1-phosphate

Which of the following is characteristic of a steroid hormone action? a. protein phosphorylation b. cell-surface receptor binding c. second messenger activation d. internal receptor binding

d. internal receptor binding

A bacterium lacking the receptor for responding to quorum-sensing signals would be unable to _______. a. divide b. synthesize a cell wall c. process food from the environment and perform glycolysis d. mount a coordinated responses with other microbes

d. mount a coordinated response with other microbes

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are _______. a. extensions of the ER b. components of the plasma membrane of osteocytes c. deposited by the circulatory system but not associated with the osteocytes d. part of the extracellular matrix

d. part of the extracellular matrix

What is autocrine signaling? a. signaling molecules diffuse locally to neighboring cells b. hormones travel long distances to target cells c. neurohormones released into the bloodstream to target cells d. production of a chemical messenger acting on the same cell

d. production of a chemical messenger acting on the same cell

A signal transduction pathway is initiated when a _______ binds to a receptor. a. cyclic AMP b. calmodulin c. G protein d. signal molecule e. tyrosine kinase

d. signal molecule

What is the difference between a steroid hormone and an amino acid as signaling molecules? a. Steroid hormones must bind to the plasma membrane receptors b. amino acids can easily pass through the membrane c. amino acids bind to internal receptors d. steroid hormones bind to internal receptors in the cytoplasm

d. steroid hormones bind to the internal receptors in the cytoplasm

How can a hormone that is present in very small quantities within the bloodstream elicit such a large response within a cell? a. only the largest cells in the body bind the signal, and thus they can elicit a large response b. the signal is always an extra-large macromolecule even though it is present in minute quantities c. cells degrade the hormone into many tiny molecules, and then each piece creates a response within the cell d. the message from the hormone is amplified many times within the cell

d. the message from the hormone is amplified many times within the cell

The cell wall of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures? a. they are composed of a mixture of lipids and nucleotides b. the must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume c. they must permit information transfer between the cell's cytoplasm and the nucleus d. they are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell e. they must block water and small molecules to regulate the exchange of matter and energy with their environment

d. they are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell

_________ help maintain polarity in some animal cells by restricting diffusion of membrane proteins. a. desmosomes b. proteoglycans c. gap junctions d. tight junctions

d. tight junctions

Which of these is the second of three stages of cell signaling? a. gene activation b. reception c. binding of a neurotransmitter to a plasma membrane receptor d. transduction e. cell response

d. transduction

_______ catalyzes the production of _____, which then opens an ion channel that releases ______ into the cell's cytoplasm. a. Protein kinase; PIP2; Na+ b. Phospholipase C; cyclic AMP; Ca2+ c. Adenylyl cyclase; cyclic AMP; Ca2+ d. Adenylyl cyclase; IP3; Ca2+ e. Phospholipase C; IP3; Ca2+

e. Phospholipase C; IP3; Ca2+

In _______ signaling, the signal molecule acts on the nearby on nearby cells. a. paracrine b. endocrine c. neuroendocrine d. neuronal e. both A and D are true f. both B and C are true

e. both A and D are true

In signal amplification: a. the target cell produces lots of the first messenger molecule b. the target cell produces lots of the second messenger molecule c. many different cellular pathways can be simultaneously controlled d. both A and C are correct e. both B and C are correct

e. both B and C are correct

Lipid-soluble signals: a. bind to cell surface receptors b. bind to cytoplasmic receptors c. are highly polar or charged molecules d. readily diffuse through the plasma membrane e. both B and D are true

e. both B and D are true

Which of these is activated by calcium ions? a. IP3 b. G protein c. PIP2 d. adenylyl cyclase e. calmodulin

e. calmodulin

Which of these acts as a second messenger? a. G protein b. adenylyl kinase c. G-protein-linked receptor d. protein kinase e. cyclic AMP

e. cyclic AMP

Where can one find pectin? a. primary cells wall of plants b. extracellular matrix of animals c. middle lamella of plants d. all of the above are true e. only "A" and "C" are true

e. only "A" and "C" are true

In general, a signal transmitted via phosphorylation of a series of proteins ________. a. requires binding of a hormone to an intracellular receptor b. generates ATP in the process of signal transduction c. activates a transcription event d. occurs within the outer plasma membrane e. results in a conformational change to each protein

e. results in a conformational change to each protein

The difference between neurotransmitters and neurohormones is that: a. neurotransmitters diffuse far from the signaling cell b. neurohormones diffuse far from the signaling cell c. neurotransmitters diffuse locally to target cells d. neurohormones diffuse locally to target cells e. just A and D f. just B and C

f. just B and C