Your SlideShare is downloading. ×
0
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Genetic Code
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Genetic Code

959

Published on

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
959
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
29
Comments
0
Likes
1
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Genetic code and protein synthesis Lodish Chapter 4.4
  • 2. Pol I transcript processed by small nucleolar ribonucleoproteins (snoRNPs) Pol III transcript S (Svedberg unit): sedimentation coefficient Ribosomal RNA is transcribed and processed in the nucleolus
  • 3. All aminoacyl-tRNA synthetases have proofreading activity enzyme tRNA binding highly dependent on tertiary structure of tRNA if product doesn’t fit correctly then proofreading activity reverses bond acceptor stem
  • 4. 3 letter code allows for 3 different reading frames
  • 5. 64 possible codons, 61 of which encode for 20 amino acids and 3 for Stops
  • 6. Some exceptions to the rule
  • 7. The base pair in the 3 rd codon position can “wobble”
  • 8. 60% 40%
  • 9. Initiation factors (eIFs) regulate ribosome assembly
  • 10.  
  • 11.  
  • 12. Polyadenylation mostly in nucleus, but can also occur in cytoplasm
  • 13.  
  • 14. Selection of the initiating AUG is determined by neighboring nucleotides In eukaryotes: A CC AUG G (Kozak sequence) or i nternal r ibosomal e ntry s ites (IRES-typical in viruses with long 5’ untranslated regions) Shine-Delgarno
  • 15.  
  • 16. Crystal structure of prokaryotic ribosome reveals three distinct tRNA binding sites: A, P and E Switches in rRNA interactions promote conformational changes RNA-driven machine peptide bond formation requires contact between 23S rRNA and tRNA acceptor stem (can be carried out w/o proteins in vitro )
  • 17. Elongation factors direct tRNAs to the A site
  • 18.  
  • 19.  
  • 20.  
  • 21. Release factors recognize STOP codons
  • 22. frameshift mutations
  • 23. What you need to know: Ribosome assembly: rRNAs are processed by snoRNPs in the nucleolus Subunit composition of ribosomes in prokaryotic/ eukaryotic cells Universal code: 64 codons, 3rd position is wobble position. Definition of codon and anticodon. tRNAs are activated by aminoacyl tRNA synthetases, which have proof- reading activity (only 1 in 50,000 is wrong) First AUG is located at a defined distance to the Shine-Delgarno sequence, which is a ribosomal docking site. Translation initiation: 5’cap binds eIF4, which in turn recruits 30S/40S subunit to mRNA. Then first tRNA binds, and then the 50S/60S subunit binds. First tRNA is always tRNA-MET. First AUG is positioned over P site 3 tRNA binding sites: A (aminoacyl), P (peptide bond) and E (exit) Elongation requires elongation factors, termination requires release factors. Release factors bind to STOP codons. Antibiotics inhibit aminoacyl-tRNA binding, tRNA transposition or cause frameshift mutations and premature chain termination.

×