Transcription, mRNA processing & Translation (ch16)

  1. Template strand
    • Transcription is done by RNA polymerase enzyme.
    • -Copies only one strand of the DNA double helix to make RNA.
    • -This strand is now a template
  2. Gene Structure
    • -Genes have three parts.
    • -Promoter
    • -Transcribed region
    • -Terminator
  3. Promoter
    • -Controls the transcription
    • -The enzyme (RNA polymerase) that makes RNA binds to the promoter with the help of other proteins known as transcription factors.
    • -transcription complex formed.
    • -Starts copying gene
  4. What two regions are important in the prokaryotes?
    • -Around -10 region
    • -Around the -35 region
  5. Numbering of Nucleotides
    • Nucleotides downstream get + numbers and upstream get - numbers.
    • -Promoters get - numbers.
  6. Sigma Factor
    • Binds to the promoter, and opens the double helix
    • -RNA polymerase copies the template strand of DNA
  7. Terminator
    -RNA polymerase reaches terminator, the transcription ends.
  8. TATA Box
    • -Its around the -30 region
    • -transcription factor protein called TATA binding protein binds to the box.
    • -Helps RNA polymerase to bind to the promoter.
  9. mRNA in Eukaryotes
    • -Included in the nucleus
    • -vefore mRNA comes out of the nucleus, they remove introns and rejoins exons by splicing .
    • -makes mRNA shorter than the gene it was copied from.
  10. Cap
    • -cap is added to the 5' end of the mRNA.
    • -protects it from damage
    • -directs ribosomes towards the 5' end
  11. poly (A) tail
    • -added to the 3' end
    • -protects the 3' end from damage.
  12. Translation
    • -Once mRNA comes to the cytoplasm, ribosomes start translating them.
    • -3 steps of translation
  13. Initiation of Translation
    • -small subunit of ribosome finds the mRNA, binds to a region close to the first ATG with the help of initiation factor proteins.
    • -tRNA arrives to start the AUG codon
    • -Binds to the AUG start codon with help of more initiation factors.
    • -large subunit of ribosomes binds to this complex
    • -Use energy from GTP to help these processes.
  14. Elongation of Translation
    • -start moving down the mRNA
    • -there are 3 sites for tRNA binding
    • -A site, P site, and E site
    • -
  15. A-site
    binds the incoming tRNA that brings the amino acid
  16. P-site
    The amino acid carried by it makes the peptide bond with the amino acid that is attached to the tRNA at the P site.
  17. E-site
    • When the ribosomes movies, the tRNAs shift positions.
    • -The first tRNA is now pused to the E-site, where it exits the ribosomes.
    • -A site opens up, next amino acid binds .
    • -process continues until ribosome reaches a stop codon.
  18. Termination of Translation
    • -When ribosome reaches the stop codon, there is no tRNA for that.
    • -protein called release factor vinds to the A-site.
    • -This dissociated the mRNA from the ribosome, the two subunits separate, and the protein chain is released.
    • -This terminates the translation
    • -More ribosomes bind to the 5' side of the mRNA
Card Set
Transcription, mRNA processing & Translation (ch16)
Exam 3