Name_________________________________________________________Unit4:Cellcommunication

1. DescribethewaysCellscancommunicatewithoneanotherA. Identifythetypeofcommunicationineachdiagramasdirectcontact,shortdistance,orlong

distanceANDJUSTIFYyouranswerforeach

Directcontact-celltocellrecognition Shortdistance-localregulators(ligands)cellSurfacemoleculesattachtoeachothersending releasedandtravelonlyashortdistanceasignal (cellsnotconnectedtoeachother)small gapbetweenthem

Directcontact-havejunction Shortdistance-localregulatorsAllowingmoleculestofreely (ligand)releasedandtravelonlya Passbetweenadjacentcells shortdistance Hormones(ligands)travel Throughbloodstream Activatecellsindifferentpartof body

B. ExplainWhycellcommunicationisimportant- The ability for cells to send messages quickly and efficiently enables cells to coordinate activities and complete

cellular processes when needed

2. ExplainhowcellscommunicationwithoneanotherA. Identifytheligandinthefollowingdiagram

B. Explainthepurposeoftheligand- Bind to the receptor on a target cell activating the target cell to complete a specific process/function

C. Describehowaligandcanactivateacell- The ligand must have the correct shape and charge to fit into the receptor on a target cell. Once in the receptor,

the ligand causes a conformational change

3. DescribehowdifferenttypesofligandsinteractwithacellforcommunicationA. Describethestructuralpropertiesofasteroidhormone

- Steroid hormones are derived from cholesterol are lipids so they are hydrophobic/ non polar molecules that are soluble with the plasma membrane allowing them to easily pass through the membrane

B. IDENTIFYthelocationofthereceptorthatasteroidhormonewillbindwithandEXPLAINwhyitmustbindtothereceptorinthatlocation

- Steroid hormones bind to receptors in the cytosol since they are hydrophobic/nonpolar and can pass through the nonpolar fatty acids tails in the plasma membrane

C. Describethestructuralpropertiesofaproteinligand- Protein ligands are made of amino acids so they are hydrophilic/polar.

D. IDENTIFYthelocationofthereceptorthataproteinhormonewillbindwithandEXPLAINwhyitmustbindtothereceptorinthatlocation

- Protein hormones bind to membrane bound receptors. Since they are hydrophilic/polar and the membrane is

nonpolar, they will not readily pass through the membrane

E. IDENTIFYthetypeofligandthatisinthediagramandEXPLAINwhyyouchosethattypeofligand

-steroidligandsinceitisabletopassthroughtheplasmamembraneandbindtoareceptorinthecytosolwhichaltersgeneexpression(transcriptionandtranslation)

Name_______________________________________________________ Unit4:LigandsandSignalTransductionReview

1. LigandscanallowthemovementofIons

A. Describehowligandsallowforthemovementofionsthroughaligandgatedionchannel

- Ligands attach to the channel protein causing a conformational/shape change in

the channel proteins resulting in the opening of the channel allowing a specific ion to flow through as facilitated diffusion

B. Explaintheimportanceofligandsongatedionchannels- They act as the signaling molecule. Regulating the movement of the ions through

the membrane. When they attach it opens the ion channel because they cause a conformational change

2. Ligandscanactivatethecellwhichleadtoasignaltransduction.Signaltransductionpathwayslinksignalreceptionwithcellularresponses.A. statethedifferencebetweenatargetcellandnon-targetcellandexplainwhyyouwouldnot

wanteverycellinthebodytocontaineverytypeofreceptor- A target cell will have the correct receptor to fit with the ligand which leads to activation of a cell signal. A non

target cell lacks the correct shape receptor so it will not be activated by the ligand since the ligand is unable to attach. If all cells contained receptors for all ligands, it wouldn’t be as efficient and energy would be wasted when a reaction occurs and is not needed

B. Definesignaltransductionpathwayandexplaintheimportance

- Ligand binding to a receptor on cell protein causing Chemical reactions to occur in the cell resulting in a

response. Signal transduction pathways regulate cell functions

C. Identifyandexplainthethreestagesinthesignaltransductionpathway

Stages1.2.3.

Explainstages:

1. Reception-ligandbindingtoareceptortoinitiatesignaling

2. Transduction-anintracellularcascadethattransfers/amplifiesthesignalfromthemembranetothenucleusorothercellulareffectors

3. Response-activationofcellactivity-cellgrowth,secretionofmolecules,orgeneexpression(transcriptionoftargetgeneisstimulatedorrepressed)andcellfunction,whichmayalterphenotypeorresultinprogrammedcelldeath(apoptosis).

3.Cellscommunicatebygenerating,transmitting,receiving,andrespondingtochemicalsignals.Describetheroleofcomponentsofasignaltransductionpathwayinproducingacellularresponse.Aseriesofstepsareneededtocompletethesignaltransductionpathwayandelicitaresponse.ExplainwhatisoccurringateachstepbyansweringeachquestionStep1:LigandbindingtothereceptorproteinA. CircleandIdentifytheLigandinthesignaltransductionpathwaydiagrambelow

B. DESCRIBEwhathappenstothereceptorproteinwhentheligandbindsandEXPLAINits

importanceThe receptor protein (example G protein) has a shape change which activates the protein stimulating the production of a secondary messenger

Step2:ActivationoftheenzymeadenylylCyclase

C. Describetheprocessthatactivatesadenylylcyclase

- The subunit from the activated G protein attaches to adenylyl cyclase activating it

D. Explainwhatadenylylcyclaseisresponsibleforoncetheenzymeisactivated

- It catalyzes the conversion of ATP to cAMP which is the secondary messenger

Step3:PhosphorylationCascadeE. CircleandlabelthesecondarymessengerinthediagramonthepreviouspageandDESCRIBEthe

overallroleofcAMPonthesignaltransductionpathway- It acts as a second messenger that helps relay and amplify the signal within the cell. It relays the

signal from the plasma membrane to the enzyme molecules in the cytosol.-

F. ExplainhowcAMPactivatesaphosphorylationcascade

- cAMPactivatesproteinkinase.OnceproteinkinaseisactiveitactivatesotherenzymesbytransferringaphosphatefromATPphosphorylatingotherenzymesactivatingthem

G. Describewhathappensduringaphosphorylationcascade- one enzyme phosphorylates another by transferring a phosphate from ATP, causing a chain

reaction leading to the phosphorylation of thousands of proteins.

H. ExplaintheimportanceofaphosphorylationcascadeSignalingcascadesrelaysignalsfromreceptorstocelltargets,oftenamplifyingtheincomingsignals,resultingintheappropriateresponsesbythecell,Step4:Response

I. Identifythetypesofresponsesthatcanoccurasaresultofsignaltransductioncellgrowth,secretionofmolecules,orgeneexpressionandcellfunction,whichmayalterphenotypeorresultinprogrammedcelldeath(apoptosis).

J. Identifythetypeofresponseinthediagramsbelow

Geneexpressionby releaseofmoleculesafter transcriptionfactorsSteroidhormone breakdownofglycogen activatedleadingtogene Expression

4. Thesignalisoftenamplifiedinthecell.A. DESCRIBEwhatamplificationisANDEXPLAINitsimportance

he number of signaling molecules that are produced or activated increases with each step in the pathway as several enzymes are activated. This results in the response being carried out multiple times instead of just once

B. CircletheamplificationareaInthediagramtotheright

5. PREDICTthetypeofmedication(whatphysicalpropertieswouldbepresent)thatcouldinhibitcyclic

AMPandturnoffasignalingpathwayANDJUSTIFYyourpredictionThemedicationwouldhaveashapeallowingittofitwithcAMPandwouldneedtobehydrophobic/nonpolar.Thiswouldallowittobesolubleandeasilypassthroughthemembranesincetheplasmamembraneisalsononpolarwiththefattyacidtails

6. Explainwhatwouldoccuriftherewasamutationinthereceptorprotein- Amutationresultingfromachangeinaminoacidswouldchangetheoverallshape,charge

ofthereceptor(polar/nonpolar).Theligandwouldnolongerfitwiththereceptorsothecellwouldnotbeactivated

Name_______________________________________________________________Unit4:FeedbackandCellCycle1. Timingandcoordinationofbiologicalmechanismsinvolvedingrowth,reproduction,andhomeostasis

dependonorganismsrespondingtoenvironmentalcues.A. Eachphysiologicalconditioninthebodyhasasetpoint.Explainwhatasetpointisandgive

examplesconditionsinthebodythathaveasetpoint- Setpointistherangeorlevelthebodywantstobeat/maintainforthatphysiologicalcondition

tobeathomeostasis(exampleofphysiologicalconditiontomaintain-glucoselevel,bodytemperature,sodiumconcentration)

B. IdentifythetypesoffeedbackmechanismsthatoccurinorganismsandExplainwhyorganismsusefeedbackmechanisms

- Identify: Negative feedback and positive feedback- Explain: maintain their internal environments and respond to internal and external environmental changes.

2. Negativefeedbackworkstomaintainhomeostasisintheorganism/cell

C. Describewhatisoccurringintheorganism/celltorequireanegativefeedbackmechanism

- There is a Change from the set point ( increasing or decreasing from set point)( glucose level rises as a result of eats)

D. Explainhowthenegativefeedbackprocessworkstomaintainhomeostasisintheorganismwhenthereisachangetothesetpoint

- When there is a change in the set point as a result of a stimulus, negative feed works to reverse the change(

inhibit the ability of the stimulus to continue) and return the system to its set point.

E. Forthefollowingnegativefeedbackexamplebelow:IdentifyONEchangethatisoccurringtothesetpointandEXPLAINhownegativefeedbackworkstoreturnthesystembacktoitstargetsetpoint

- Stimulus- Rise in glucose level from the set point

Negativefeedback:

1. pancreasactivatedtoproduceandreleaseinsulin.2. Insulinbindstoreceptorsinliverandtissuecellswhichtriggerssignaltransductionintheliverandtissuecells.3. Responseofsignaltransductionmovesglucosetransportproteinstoplasmamembrane

Result:glucosemovesintocellsandgetsstoredasglycogen…loweringthebloodglucoselevelF. Forthenegativefeedbackexampleanswerthefollowing:- DescribeamutationthatcouldoccurMutation in the amino acid( substitution/deletion/indention) sequence in the insulin receptor protein changing the shape of the receptor

- Predicttheimpactthemutationwouldhaveonthenegativefeedbackloop

The blood glucose level will remain high.

- JustifyyourpredictionInsulin can no longer bind to the insulin receptor protein on cells so signal transduction will not occur.

As a result the glucose transport proteins will not be moved to the plasma membrane, so glucose will not be able to move into the cell

3. Feedbackinhibitioncanregulateenzymecatalyzedpathways

A. DescribethefeedbackthatisoccurringinthediagrambelowandEXPLAINitsimportanceTheallostericsiteontheenzymeisoccupiedcausingashapechangeintheactivesite.Thesubstratecannolongerbindshuttingdown(inhibiting)theenzymecatalyzedpathway.Nomoreproductwillbeproduced.Explain:byinhibitingtheprocess,thebodyconservesenergy

B. Identifythestructurethatisactingastheallostericregulatorintheabovefeedback- The end product

4. Explainhowpositivefeedbackaffectshomeostasis.A. Explainwhatpositivefeedbackmechanismsdototheresponsesandprocessinorganisms

mechanismsamplifyresponsesandprocessesinbiologicalorganisms.

B. Describeapositivefeedbackresponseasaresultofachangeinthesetpoint.

Thevariableinitiatingtheresponseismovedfartherawayfromtheinitialsetpoint.Amplificationoccurswhenthestimulusisfurtheractivated,which,inturn,initiatesanadditionalresponsethatproducessystemchange.

C. Explainthepositivefeedbackthatisoccurringinthediagrambelowandstatetheendresultofthispositivefeedback

- Positive feedback continues the stimulus moving away from the initial set point- Ripening produces ethylene which signals others to ripen and more production of ethylene. End result is ripe

fruit

5. Ineukaryotes,cellsdivideandtransmitgeneticinformationviatwohighlyregulatedprocesses.A. IdentifythephasesofthecellcycleandGiveabriefdescriptionofeachphase

Interphase-growthofcellandsynthesisofDNAMitosis-nucleardivision

B. DescribewhatisoccurringduringtheG1,SandG2phasesofinterphase- G1-growthofcellandreplicationoforganelles

- S-DNAreplication

- G2-continuedgrowthofcell

C. DrawabargraphtoshowtheamountofDNAthatwouldbefoundinthedifferentstagesofthecellcycleiftheinitialamountofDNAwas4

AmountofDNAperphase NumberofChromosomesperphase

8 7 6 5 4 3 2 1 0

Initialcell

Interphase

Prophase

Metaphase

Anaphase

Telophase

Daughtercells

8 7 6 5 4 3 2 1 0

Initialcell

Interphase

Prophase

Metaphase

Anaphase

Telophase

Daughtercells

D. Drawabargraphtoshowthenumberofchromosomesthatwouldbefoundinthedifferentstagesofthecellcycleiftheinitialnumberofchromosomeswas4

E. Identifythestageacellenterswhenitisnolongerdividing G0

6. ExplainhowmitosisresultsinthetransmissionofchromosomesfromonegenerationtothenextA. IdentifythevariousrolesofMitosisinthebodyMitosisplaysaroleingrowth,tissuerepair,andasexualreproduction.

B. Identifythefollowingstructuresinthediagrambelow:sisterchromatid,centromere,spindlefibers,kinetochore,chromosome

C. Describewhatisoccurringineachofthestagesofmitosis- Prophase

Chromosomes begin to condense from chromatin; spindle apparatus assembled. Nuclear envelope disperses. chromosomes connect to spindle apparatus fibers

- MetaphaseChromosomes align on metaphase plate/plane

- Anaphase-Paired chromatids will separate, and the new daughter chromosomes will move toward

opposite poles of the cell

- Telophase-Chromosomes disperse back to chromatin form, nuclear envelope reassembles

D. Explaintheimportanceofcytokinesis- Dividesthecytoplasmtoproducetwodaughtercells

E. Foreachpicturebelow,Identifythestagethecellisin(theyarenotinorder):interphase,prophase,metaphase,anaphase,telophase/cytokinesis

Interphase metaphasetelophase/ prophase anaphase cytokinesis

F. Foracellthathasundergonemitosis,Describehownewlyformeddaughtercellscomparetotheoriginalcell

- Geneticallyidentical

Name_____________________________________________________________________ Unit4:cellRegulation1. Describetheroleofcheckpointsinregulatingthecellcycle.Anumberofinternalcontrolsor

checkpointsregulateprogressionthroughthecycle.A. Labelthe3checkpointsthatexistinthecellcycleandEXPLAINtheoverallimportanceof

checkpointsinthecellcycle

- regulate the progression through the cell. ensures the cell has completed the processes correctly before progressing

A. DescribetheRoleofcyclinincellregulationCyclebindstoCdKactivatingtheenzyme

B. DescribetheroleCdK(cyclindependentkinase)inthecellcycleRegulatesthecellcycle.Whenactivated,causesphosphorylationofspecifictargetproteins

C. IdentifythecomponentsofMPFANDDESCRIBEtheroleofMPF(maturationpromotingfactor)- Cyclin,CdKandaphosphate.TheamountofMPFdeterminesifthecellcanprogresspastthe

checkpointandcontinueinthephasesofthecellcycle.IfenoughMFP,thecheckpointhasbeenmet

D. Explaintheimportanceofeachcheckpointinthecellcycle- G1-ensurethecellisgrowingproperly

- G2–ensuresDNAhasreplicatedcorrectly

- M–ensuresthatthespindlefibersareattachedcorrectly.(ifnot,nondisjunctionwouldoccur)

2. Interactionsbetweencyclinsandcyclin-dependentkinasescontrolthecellcycle.A. DescribewhathappenstotheconcentrationofCyclinduringthecellcycleandExplainwhythe

changeinconcentrationhappens

Theconcentrationofcyclinincreasesbcgrwothfactorsstimulatethesynthesisofcyclin.Asthecellcontinuesthroughinterphaseandintomitosis,thecyclinscontinuetobesynthesizedincreasingtheconcentration

B. DescribetheimpactthechangeinCyclinhasontheconcentrationofMPFAstheconcentrationofcyclinincreases,theconcentrationofMPFincreasessincemorecyclinsarepresenttobindtomoreCdKs

C. DescribewhathappenstotheconcentrationofMPFasthecellprogressesthroughthecellcycleANDEXPLAINwhytheconcentrationofMPFchanges

The concentration of MPF increases in the concentration as cyclin increases in concentration binding with more CdK

D. ExplainhowtheconcentrationofMPFisusedateachcheckpointtodetermineifthecellwillcontinuepastthecheckpointornotadvance

TheremustbethecorrectconcentrationofMPFdoadvancepasttheG2checkpointandcontinuetomitosis

E. Graphtheconcentrationofcyclin,andMPFduringthecellcycle(interphaseandmitosis)andexplainwhatishappeningtotheconcentrationsofeach

F. ExplainwhytheconcentrationdecreasesasthecellprogressesthroughmitosisCyclindegradesasisthecellprogressesthroughmitosis

G. ExplainwhathappenstothecellifthecelldoesintopastheG1checkpoint3. Disruptionstothecellcyclemayresultincancerand/orprogrammedcelldeath(apoptosis).

A. Describetheroleofthep53proteinon

thecellcycleInhibitsthecellfromcontinuingthecellcycleifDNAdamaged.IfDNArepaired,cellallowedtocontinuethroughcellcycle.Ifcan’tberepairedtriggerapoptosisofcell

B. Explaintheimportanceofthep53protein

- Defense against cancer and prevents tumors from forming

C. DescribetheoutcometothecellwhenapoptosisoccursANDEXPLAINwhythisprocessisnecessary

- Apoptosis is the programmed cell death

which is needed if the cell cannot be repaired

D. Predictwhatwouldhappentothecellcycleiftherewasamutationinthep53geneANDJUSTIFY

ThecellcyclewouldnotbeinhibitediftherewasdamagedDNAandwouldcontinuetodivide.Themutationinthep53genewouldchangetheaminoacidsequenceresultingintheshapeoftheproteinbeingwrong

E. DescribewhathappenstothelengthofthecellcycleinacancerouscellANDEXPLAINwhythischangehappens.

- Cell cycle would be shortened since cancerous cells since the regulatory process (checkpoints) does not occur resulting in uncontrolled cell division

F. PredictwhatwouldhappentothecellgoingthroughthecellcycleifamedicationinhibitstheformationofcyclinANDJUSTIFYyourprediction

ThecellwouldnotprogressthroughthecellcyclesincecyclewouldnotbepresenttoactivateCdKandnoMPFwouldform