Molecular Genetics

Molecular Genetics

1. Transcription

   • Initiation
     • Step-By-Step
       • Promoter recognized by Transcription Factors
         • RNA Pol. II recruits by transcript factors
           • Transcription begins and continues 3'-5' along template strand
   • Elongation
     • Complementary RNA nuctids. add to growing RNA (U/T)
   • Termination
     • Step-by-Step
       • Polyadenylation signals to cut from polymerase
         • RNA is PRE-mRNA
           • RNA Pol. falls off template strand
   • Purpose
     • Converts DNA to RNA
     • Protects information
     • Multiple RNA copies for more protein production
   • Post-Transcript Mods (Eukaryotes Only)
     • Purpose
       • Export of mRNA from nucleus
       • Protect mRNA from degradation
       • Facilitated proper translation
     • 5' Capping
       • Modified guanine
         • Add 5' end during transcript
     • Poly-A-Tail
       • multiple adenines added at end of signal--3'
     • Intron Splicing
       • Spliceosome
         • Removes introns (snRNA)
           • Products: mature mRNA and circular intron
       • Alternative Splicing
         • 1 gene codes multiple proteins

2. Translation

   • Purpose
     • Convert mRNA to Protein
   • Ribosomal Structure
     • Large Unit
       • Small unit
     • mRNA Binding Sites
       • Exit
       • Peptidyl-tRNA bind site
       • Aminoacyl tRNA Bind site
     • Reading Frame
       • Codons
         • 3 mRNA Nucleotides and 1 amino acid
         • Stop
           • UAG, UAA, UGA
     • adapters with an anticodon
     • Each bind to ONE specific amino acid at Carboxylic Acid
   • Initiation
     • tRNA (Transfer RNA)
       • Step-by-step
         • Initiator t-RNA (methionine) binds to small unit with initiation factors
           • small ribosomal subunit/initiator t-RNA binds m-RNA 5' cap to 5' end
             • Scan toward 3' end until start codon
               • AUG
   • Elongation
     • Step-by-step
       • Current tRNA at P-Site
         • moving toward 3'New tRNA add to A-site
           • AA ads to carboxy end
             • Chain grows to A-site
               • Large shifts 1st one codon
                 • Small shifts
                   • tRNA in P-site now in E-site and A-site now P-site
                     • E-site Ejects and new A-site tRNA is added
   • Termination
     • Step-by-step
       • When A-site reads stop codon
         • UAG, UAA, UGA
           • Release factor releases peptide chain and ribosomes dissociate

3. Gene Expression

   • Purpose
     • efficiency and adaptive
     • cells have same genome; need regulation
     • Results in different cell types
   • Step-By-Step
     • 1. DNA-->RNA (single)
       • 2. RNA to mRNA
         • 3. Out of Nucleus thought Nuc pore; direction
           • 4. Translation Route-->Protein
             • Protein-->Activated!
           • 5. Degredation Route

4. Protein Degredation