Ch 5 Nucleic Acids excerpt -...

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    BIOL221BIOL221

    Ch5(excerpt)Ch5(excerpt)

    NucleicAcidsNucleicAcids

    NucleicAcidsNucleicAcids

    Storeandtransfergene3cinforma3on

    Gene

    Unitofinheritancethatcodesfortheaminoacidsequenceofapolypep3de

    Makesaprotein

    GenesaremadeofDNA

    Anucleicacid

    TheRolesofNucleicAcidsTheRolesofNucleicAcids

    Twotypesofnucleicacids:

    Deoxyribonucleicacid(DNA)

    Ribonucleicacid(RNA)

    DNA

    Codesforproteins

    Providesdirec3onsforitsownreplica3on

    DirectssynthesisofmessengerRNA(mRNA)

    Containsinforma3onforproteinsynthesis

    Proteinsynthesisoccursinribosomes

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    mRNA

    Synthesis ofmRNA in thenucleus

    DNA

    NUCLEUSCYTOPLASM

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    mRNA

    Synthesis ofmRNA in thenucleus

    DNA

    NUCLEUS

    mRNA

    CYTOPLASM

    Movement ofmRNA into cytoplasmvia nuclear pore

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    2

    mRNA

    Synthesis ofmRNA in thenucleus

    DNA

    NUCLEUS

    mRNA

    CYTOPLASM

    Movement ofmRNA into cytoplasmvia nuclear pore

    Ribosome

    AminoacidsPolypeptide

    Synthesisof protein

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    2

    3

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    TheStructureofNucleicAcidsTheStructureofNucleicAcids

    PolynucleoFdes

    Nucleicacidpolymer

    NucleoFde

    Monomersofpolynucleo3de

    Consistsof

    Pentosesugar

    Phosphategroup

    Nitrogenousbase

    Adenine(A),Cytosine(C),Guanine(G),Thymine(T)

    Nucleoside

    por3onofanucleo3dewithoutthephosphategroup

    5 end

    Nucleoside

    Nitrogenousbase

    Phosphategroup Sugar

    (pentose)

    (b) Nucleotide

    (a) Polynucleotide, or nucleic acid

    3 end

    3C

    3C

    5C

    5C

    Nitrogenous basesPyrimidines

    Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA)

    Purines

    Adenine (A) Guanine (G)

    Sugars

    Deoxyribose (in DNA) Ribose (in RNA)

    (c) Nucleoside components: sugars

    NucleoFdeMonomersNucleoFdeMonomers

    Twofamiliesofnitrogenousbases:

    Pyrimidines cytosine(C),thymine(T),anduracil

    (U)

    singlesixmemberedring

    Purines adenine(A)andguanine(G)

    sixmemberedringfusedtoafivememberedring

    Deoxyribose

    SugarinDNA

    Ribose

    SugarinRNA

    Nucleo3de=nucleoside+phosphategroup

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    NucleoFdePolymersNucleoFdePolymers

    Nucleo3dePolymers Linkedtogethertobuilda

    polynucleo3de

    Simplyunfinishednucleicacid Adjacentnucleo3des

    Joinedbyphosphodiesterbonds(covalent)

    FormbetweentheOHgrouponthe3carbonofonenucleo3deandthephosphateonthe5carbononthenext

    Createabackboneofsugarphosphateunits

    Withnitrogenousbasesasappendages

    ThesequenceofbasesalongaDNAormRNApolymerisuniqueforeachgene

    TheDNADoubleHelixTheDNADoubleHelix

    Doublehelix Twopolynucleo3desspiraling

    aroundanimaginaryaxis,formingaDNAmolecule

    Nitrogenousbasesbondwithoneanotherinthemiddleincomplementaryfashion

    AT;CG

    Hydrogenbonds

    AnFparallel Twobackbonesruninopposite

    53direc3onsfromeachotherintheDNAdoublehelix

    OneDNAmoleculeincludesmanygenes

    Equalsonechromosome

    DNAReplicaFonDNAReplicaFon

    Semiconservedmodel

    Oneparentstrandyieldstwodaughterstrands

    Eachdaughterstrandcontainshalfoforiginalparentstrand

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    DNAandEvoluFonaryRelaFonshipsDNAandEvoluFonaryRelaFonships

    Sequencesofnucleo3desinDNA Passedfromparentstooffspring

    Twocloselyrelatedspecies AremoresimilarinDNA

    Thanaremoredistantlyrelatedspecies

    Determinedby%divergence