*LUL (_WYLZZPVU7 )YVT *LUL [V 3YV[LPU +*+)POIHTXMLV °#
=?>POIHX ]SY UMLMLLK XS RUS[&"!" ? How RNA and DNA are similar and different and how this deﬁnes their roles. ? The differences between replication , transcription and translation and the role of DNA and RNA in each process. ? How eukaryotic cells modify RNA after transcription. ? How genetic material is translated into polypeptides. ? How mutations can change the amino acid sequence of a protein and be able to predict how a mutation can result in changes in gene expression.
((((oncept °"±°% ,,,enes specify proteins via transcription and translation
./-MLUML ,-+\TVMLWWQPSU&"!" TVSKJMLWW JI] [POQPKJPO ,+,*46)()' LKQPVMLKJXW XPOML W]UXPOMLWQPW SNM TVSXMLQPUW ±SV 8:46)()'W² ? Old idea: one gene-one enzyme hypothesis ? Proposed by Beadle & Tatum – mutant mold experiments ? Function of a gene = dictate production of speciﬁc enzyme ? Newer idea: one gene-one polypeptide hypothesis Most accurate: one gene-one RNA molecule (which can be translated into a polypeptide)
-.,SS[ SNM ONMLUMLXQPKJ QPUNMSVTIHXQPSU ? Central Dogma: DNA >> RNA >> protein ± Transcription : DNA >> RNA ± Translation : RNA >> protein ? Ribosome = site of translation
Flow of Genetic Information in Prokaryotes vs. Eukaryotes
XoWnLLNe NPgLLNeWnLLNe (% XoWnLLNe 799355)& VmXoUlLLNeJJLcuUlLLNe DNA RNA ? Nucleic acid composed of nucleotides ? Double-stranded ? Deoxyribose=sugar ? Thymine ? Template for individual ? Nucleic acid composed of nucleotides ? Single-stranded ? Ribose=sugar ? Uracil ? Many different roles!
8:46)()' TSIH]W TIHU] VSSMLW QPU XPOML KJMLSS °± pre°mRNA =precursor to mRNA, newly transcribed and not edited ²± mRNA = edited version; carries the code from DNA that speciﬁes amino acids ³± tRNA = carries a speciﬁc amino acid to ribosome based on its anticodon to mRNA codon ´± rRNA = makes up 60% of the ribosome; site of protein synthesis ± snRNA =small nuclear RNA; part of a spliceosome; structural and catalytic roles !± srpRNA = signal recognition particle that binds to signal peptides "± RNAi = interference RNA; a regulatory molecule # ± miRNA ±siRNA = micro/small interfering RNA; binds to mRNA or DNA to block it, regulate gene expression, or cut it up $!± ribozyme = RNA that functions as an enzyme
:<;POML ./-MLUMLXQPKJ +*+)SLKML mRNA (5’ >> 3’) complementary to template mRNA triplets ( codons ) code for amino acids in polypeptide chain For each gene, one DNA strand is the template strand
:<;POML ./-MLUMLXQPKJ +*+)SLKML !6² different codon combinations This code is universal: all life forms use the same code .
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