Chapter 2 - Transcription - A GeneExpression...

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Gene Expression The Central Dogma For the phenotypic expression of any gene, information contained in  DNA is first  transcribed  into an RNA from where it is  translated   into the amino-acid sequence of the corresponding protein.  Phenotypes are the manifestation of the activity/function of  proteins and catalytic RNAs. DNA RNA Transcription RNA Pol + factors Protein Translation Ribosomes, tRNA aa + other factors Function Enzyme, structural element, hormone,  regulatory, etc The assumptions of the central dogma are  sound, but there are exceptions! Phenotype
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DNA Ribozymes RNA   TRANSCRIPTION REVERSE  TRANSCRIPTION rRNAs   tRNAs   mRNAs    Proteins Ribosomes TRANSLATION The Expanded Central Dogma small RNAs REGULATION
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The first step of the expression of a gene (DNA) is to transcribe  the information contained in the nucleotide sequence from  one strand (template or antisense strand) into an RNA. The  product of this transaction is a  transcript . If a gene carries information for the assembly of a protein, the  transcript is a messenger RNA ( mRNA ). The information in  mRNAs  is decoded by ribosomes and translated  by alignment of three-nucleotide codons with corresponding  tRNAs that deliver the corresponding amino acids. Transcription Translation
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Transcription and  RNA Processing Topics 1.  RNA structure. 2.  RNA synthesis. 3.  Transcription: initiation, elongation and  termination. 4.  RNA processing: cleavage of precursor  transcripts and modification of bases. 5.  RNA and protein splicing. 6.  RNA editing. Videos
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A.   The first step of the expression of a gene (DNA) is to  transcribe the information contained in the nucleotide  sequence from one strand (template or antisense  strand) into an RNA. The product of this transaction is  transcript . B.   If a gene carries information for the assembly of a  protein, the transcript is a  messenger RNA  ( mRNA ). C.  Some genes are only transcribed and never  translated. Such genes code for: 1.   Ribosomal RNAs (rRNA) 2.   transfer RNAs (tRNA) 3.   Miscellaneous RNAs that have catalytic or template functions  (spliceosome RNAs, template RNAs, etc.) Transcription
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Transcription: RNA polymerase (RNAP) catalyzed  synthesis of RNA on a DNA template Do you remember the principles of nucleic-acid synthesis? Ch. 1! RNA polymerases do  NOT  require a primer  for the initiation of  RNA synthesis. Direction of RNA  synthesis: 5’   3’ Direction of reading  of template DNA  strand: 3’   5’
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       Size Subunit  aa    Da Gene Function alpha ( ) α  329 36,511   rpoA Assembly  of RNAP, binding of some  regulatory proteins, catalysis.
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