第七章 氨基酸代谢The seventh chapter Amino acid metabolism.docx

第七章 氨基酸代谢The seventh chapter Amino acid metabolism.docx

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第七章氨基酸代谢TheseventhchapterAminoacidmetabolism

第七章.氨基酸代谢（Theseventhchapter.Aminoacidmetabolism）

Theseventhchapterisaminoacidmetabolism

Mainpointsofthischapter

First,thenutritionalroleofprotein

1.nitrogenbalance

Thetotalnitrogenbalance

Thepositivebalanceofnitrogen

Thenegativenitrogenbalance

2.essentialaminoacidsandnonessentialaminoacids

3.nutritionalvalueandcomplementationofproteins

Two.Digestion,absorptionanddecayofproteins

Three.Deaminationofaminoacids

Aminoacidsaremainlyremovedinthreeways,namelyoxidativedeamination,deamination,andcombineddeamination.

Metabolismoffour-ketoacids

1.aminoacidintoaminoacid

2.changetosugarorfat

3.oxidationenergysupply

Five.Metabolismofammonia

1.sourcesandroutesofbloodammonia:

Thesourceofbloodammonia:

byintestinalabsorption;theaminoaciddeaminationoftheaminoacidamide;hydrolysis;decompositionoftheothernitrogencompounds.

Thebloodammoniaway:

intheliverintothesynthesisofurea;aminoacids;thesynthesisofothernitrogenouscompounds;thesynthesisofasparagineandglutamine;thedirectdischarge.

2.ammoniatransportintheblood

Thealanineglucosecycle

Theroleofglutaminetransportofammonia

3.ornithinecycleandureasynthesis

Thecharacteristicsofureasynthesis:

synthesismainlyinmitochondriaandcytosoloftheliverinthesynthesisofureamolecules;consumefourATPmolecules;theargininosuccinatesynthaseisakeyenzymeinthesynthesisofurea;thetwonitrogenatomsoftheureamolecule,onefromtheNH3,asourceinASPaminoacid.

Six,thedecarboxylationofaminoacids

Catalyzedbyaminoaciddecarboxylase,coenzymepyridoxalphosphate,theproductwasCO2andamine.Understandingthephysiologicalrolesofseveralimportantamines.

Seven,theconcept,sourceandphysiologicalfunctionofonecarbonunit

Eight,S-methioninecycle

Nine.Metabolismofaromaticaminoacids

Themajormetabolicprocessesinnervetissuecellsarephenylalanine,tyrosine,DOPA,dopamine,norepinephrine,norepinephrine,andepinephrine.Dopamine,norepinephrine,andepinephrinearecollectivelycalledcatecholamines.Inmelanomacells,Duobakeintomelanoma.Ageneticdefectinphenylalaninehydroxylasecausesphenylketonuria,ageneticdefectintyrosinasethatcausesalbinism.

Exercises

First,themultiple-choicequestion

1.thefollowingaretheessentialaminoacids:

A.glutamicacidB.phenylalanine

C.alanineD.glutamine

E.cysteine

2.whichofthefollowingsubstancesdoesnotbelongtoacarbonunit?

A.CH3B.CH2

C.CH=D.CH=NH

E.COOH

3.thecarrierofacarbonunitinvivois

A.folicacid,B.,leucovorin

C.dihydrofolateD.pantothenicacid

E.biotin

4.whichofthefollowingisnotonlytheketogenicaminosugaraminoacids?

A.leucineB.tyrosine

C.isoleucineD.threonine

E.glycine

5.aminoacidsthatcanbeconvertedintotaurineare:

A.leucineB.aspartate

C.valineD.glycine

E.cysteine

6.thefollowingaminoacidsthatarenotinvolvedinproteinbiosynthesisare

A.glycine,B.ornithine

C.proline,D.arginine

E.valine

7.whichofthefollowingaminoacidscanproducevasodilators?

A.

Tryptophan,B.,proline

C.glutamicacidD.histidine

E.hydroxyproline

8.whichofthefollowingstagesofureasynthesisoccursinmitochondria?

A.producescitrulline,B.argininehydrolysis

C.producesarginine,D.,toproducearginineinsteadofsuccinicacid

E.ormoreiswrong

Whatkindofsubstancemetabolismdoes9.PAPSmainlycomefrom?

A.methionineB.taurine

C.cysteineD.homocysteine

E.ormoreiswrong

10.whichofthefollowingtwokindsofnitrogendoesureacomefrom?

A.ornithineandmethotrexatephosphate

B.asparticacidandaminoformylphosphate

C.-amino-and-aminogroupsofornithine

D.-aminoacidsandarginine-aminogroupsofcitrulline

E.ornithine-aminoandglycine

11.,themostimportantmetabolicpathwayofammoniainadultsis

A.formsthenonessentialaminoacidB.,formingtheessentialaminoacidC.,formingNH4+,whichisexcretedwithurine

D.formsureaE.,formingpurineandpyrimidinenucleotides

12.themaincauseofelevatedbloodammoniais

A.,excessiveintakeofprotein,B.,liverdysfunction

C.soapwater（alkaline）enema,intestinalabsorptionofammoniaincreased

D.renaldysfunctionisnotmorethanE.

13.whichaminoacidsareproducedbytheconversionofcatecholamines?

A.tryptophan,B.glutamicacid,C.aspartate,D.tyrosine,E.lysine

Theimportantroleof14.S-inmethionineis

A.supplementationmethionine,B.synthesis,vitaminC.,methyl

D.producesadeninenucleosideE.

Homocysteinesynthesis

Inthe15.brain,-aminobutyricacidisproducedbywhichofthefollowingmetabolites?

A.asparticacidglutamicacidB.C.oxoglutarateD.oxaloaceticacid,E.malicacid

16.theammoniaproducedinthekidneysismainlyderivedfromammonia

CombineddeaminationofA.aminoacids

HydrolysisofB.glutamine

HydrolysisofC.urea

NonoxidativedeaminationofD.aminoacids

OxidationofE.amines

17.themajorcomponentofnonproteinnitrogeninthebloodis

A.urea,B.,uricacid,C.,creatine,D.polypeptide,E.aminoacid

18.canthefreeammoniabeproducedbythecontinuousactionofalanineandalphapyruvate,alanineaminotransferase,andwhichofthefollowingenzymes?

A.B.C.aspartateaminotransferaseenzymeglutamatedehydrogenase

D.glutaminesynthetase,E.,glutaricdehydrogenase

19.inthepresenceofornithineandaminoacylphosphate,thesynthesisofureaalsoneedstobeadded

A.arginine,B.HCO3,C.,citrulline,D.,asparticacid,E.arenotabove

20.ureacycle

TheA.needstobesuppliedbytheCTP

B.asparticacidcontainscarbonmoietiesthatareincorporatedintoarginine

C.arginineisadirectprecursorofcitrulline

D.needsornithine

E.isadirectproductofoxaloacetateargininosuccinate.

Themainrouteofammoniainthebrainis21.

A.synthesisureaB.diffusionintobloodC.synthesisglutamine

D.synthesisofaminoacidsE.synthesisofpurine

22.whichofthefollowingcompoundscannotbesynthesizedfromtyrosine?

A.thyroxine,B.,epinephrine,C.

Dopamine,D.,phenylalanine,E.melanin

23.themainmeansofdeaminationofaminoacidsinmuscleis

CombineddeaminationofA.

B.L-oxidativedeaminationofglutamicacid

C.ammoniatransferaction

D.ornithinecycle

E.purinenucleotidecycle

Whichofthefollowing24.kindsofaminoacidsaftertransaminationcangenerateoxaloacetate

A.glutamicacid,B.,alanine,C.,threonine,D.,aspartate,E.,proline

25.whichofthefollowingsubstancesrequiresthesynthesisofasparticacid?

A.porphyrinB.steroidsC.sphingolipidD.pyrimidineE.coenzymeA

Whichvitamindoesthecoenzymeof26.transaminasecontain?

A.Vit.B1,B.Vit.B12,C.Vit.C,D.Vit.B6,E.Vit.D

27.whichofthefollowingsubstancesistheformofammoniastorageandtransportationinthebody?

A.glutamicacid,B.,tyrosine,C.,glutamine,D.,glutathione,E.,asparagine

28.whichofthefollowingsubstancesisthesupplierofsulfateradicalsinthebody?

A.ATPD.FADE.GMPB.NADPC.PAPS

29.albinismisduetodeficiency

A.tryptophanhydroxylase,B.tyrosinase,C.phenylalaninehydroxylase

D.prolinehydroxylaseisnomorethanE.

30.aminoacidsthatcanbeconverteddirectlyto-glutaricacid

A.ASP,B.,alanine,C.,glutamicacid,D.,glutamine,E.,asparagine

31.aminoacidsthatcanbeconvertedtoacetylCoAare

A.arginineB.

Leucine,C.,methionine,D.,threonine,E.,serine

32.theenzymethatrequiresN-acetylglutamateasanactivatorintheornithinecycleis

A.formylphosphatesynthetase

B.glutamyltransferase

C.argininesynthetase

D.argininesynthase

E.argininelyase

33.thevitaminsnecessaryfortheproductionofmethioninebyhomocysteineandN5-are

A.B.C.D.folicaciddihydrofolatetetrahydrofolateE.N5-methyltetrahydrofolicacidvitaminB12

34.whatisthelackofenzymesintheliverofpeoplewithphenylketonuria?

A.phenylalaninehydroxylaseB.tyrosinaseC.urineblackacidoxidase

D.tyrosineaminotransferaseE.versuspyruvateoxidase

Two.Fillintheblanks

Thedeaminationof1.aminoacidshasthreemainways.

2.anenzymethatcatalyzestheaminoacidreactionofaminoacids,saidthecoenzymeisthelatter,whichactsinthereaction.

3.thesimultaneousdeaminationrequiressimultaneousparticipationoftwoenzymes,thecentralsubstanceinthereactionbeing.

4.aspecificcombinationofdeaminationoccurringinmuscletissueisknownasthenucleotideinvolvedinthereaction,

Finally,theNH3isremovedbytheactionofanenzyme.

5.accordingtothemetabolictransformationofaminoacids,20aminoacidscanbedividedinto,and

Threecategory.

6.ammoniaistransportedmainlyinthebloodaswellasintwoforms.

7.theureaformationprocessiscombinedwiththethreecarboxylicacidcycle.

Thebasisofthe8.hepaticcomaammoniaintoxicationtheoryistheincorporationofammoniaintothebrain,resultinginadecreaseinbraintissueresultinginreducedATPproduction.

Theproductis9.aminoaciddecarboxylation,thesecatalyticreactionoftheenzyme,thecoenzyme.

10.acarbonunitinthebodyhas,,,and

Andsoforth,thecarrierofacarbonunitinmetabolismis.

11.catecholamineinclude,and,anditsformationand

Metabolismiscloselyrelated.

Three.Briefquestions

1.combineddeamination

2.purinenucleotidecycle

3.alanineglucosecycle

4.ornithinecycle

Five

Onecarbonunit

6.methioninecycle

7.-glutamylcycle

Four.Questionsandanswers

1.whatarethecommonpathwaysforcatabolismofvariousaminoacidsinthehumanbody?

Thebasicmetabolicprocessisbrieflydescribed.

2.whatisthemainmetabol