1 BIOL 221 BIOL 221 Ch 5 (excerpt) Ch 5 (excerpt) Nucleic Acids Nucleic Acids Nucleic Acids Nucleic Acids • Store and transfer gene3c informa3on • Gene • Unit of inheritance that codes for the amino acid sequence of a polypep3de • Makes a protein • Genes are made of DNA • A nucleic acid The Roles of Nucleic Acids The Roles of Nucleic Acids • Two types of nucleic acids: • Deoxyribonucleic acid (DNA) • Ribonucleic acid (RNA) • DNA • Codes for proteins • Provides direc3ons for its own replica3on • Directs synthesis of messenger RNA (mRNA) • Contains informa3on for protein synthesis • Protein synthesis occurs in ribosomes
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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
3′C
3′C
5′C
5′C
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)
• singlesix‐memberedring
• Purines
• adenine(A)andguanine(G)
• six‐memberedringfusedtoafive‐memberedring
• Deoxyribose
• SugarinDNA
• Ribose
• SugarinRNA
• Nucleo3de=nucleoside+phosphategroup
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NucleoFdePolymersNucleoFdePolymers
• Nucleo3dePolymers
• Linkedtogethertobuildapolynucleo3de
• Simplyunfinishednucleicacid
• Adjacentnucleo3des
• Joinedbyphosphodiesterbonds(covalent)
• Formbetweenthe–OHgrouponthe3′carbonofonenucleo3deandthephosphateonthe5′carbononthenext
• Createabackboneofsugar‐phosphateunits
• Withnitrogenousbasesasappendages
• ThesequenceofbasesalongaDNAormRNApolymerisuniqueforeachgene
TheDNADoubleHelixTheDNADoubleHelix
• Doublehelix
• Twopolynucleo3desspiralingaroundanimaginaryaxis,formingaDNAmolecule
• Nitrogenousbasesbondwithoneanotherinthemiddleincomplementaryfashion
• A‐T;C‐G
• Hydrogenbonds
• AnFparallel
• Twobackbonesruninopposite5′→3′direc3onsfromeachotherintheDNAdoublehelix
• OneDNAmoleculeincludesmanygenes
• Equalsonechromosome
DNAReplicaFonDNAReplicaFon
• Semi‐conservedmodel
• Oneparentstrandyieldstwodaughterstrands
• Eachdaughterstrandcontainshalfoforiginalparentstrand
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DNAandEvoluFonaryRelaFonshipsDNAandEvoluFonaryRelaFonships
• Sequencesofnucleo3desinDNA
• Passedfromparentstooffspring
• Twocloselyrelatedspecies
• AremoresimilarinDNA
• Thanaremoredistantlyrelatedspecies
• Determinedby%divergence
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