1. Synthesis of RNA

2. Synthesis of RNA from a NDA template is called transcription. Genes are transcribed by enzymes called RNA polymerases that generate a single-stranded RNA.

3. Primary transcript The RNA strand that is initially generated. Direction The DNA template is copied in the 3’ to 3’ direction. The RNA transcript is synthesized in the 5’ to 3’ direction. RNA polymerases The DNA template is copied in the 3’ to 3’ direction. The RNA transcript is synthesized in the 5’ to 3’ direction. They can initiate the synthesis of the new strands in the absence of a primer.

4. Action of RNA polymerases

5. Synthesize RNA from DNA. 5’- 3’ direction.

7. Recognize the startpoint for transcription of each gene.

8. Sensitive to signals that reflect the need for the gene product and control the frequency of transcription.

9. Types of RNA polymerases

10. Eukaryote cells Polymerase I produces most of the rRNAs Polymerase II produces most of the mRNAs Polymerase III produces small RNAs such as tRNA and 5 S RNA. All have the same mechanism of action. Recognize different type of promoters.

11. Prokaryote cells Bacterial cells have a single RNA polymerase to generate all of the different types of RNA (mRNA, rRNA, and tRNA). Tuberculosis Rifampicin Rifampicin Bacterial RNA polymerase

13. Alert Do Not Eat Death Cap

14. Amanita phalloides (the death cap) These mushrooms contain toxin α -amanitin . Block the action of RNA polymerase II . 40-90% die within a few days.

16. Recognition of DNA by RNA polymerases

17. RNA polymerase must recognize which genes to transcribe. Transcribed genes are only a small fraction of the total DNA. The genes that are transcribed differ from one type of cell to another Change with changes in physiologic conditions.

18. The signals in DNA that RNA polymerase recognizes are called promoters . Promoters are sequences in DNA that determine the startpoint and the frequency of transcription. Often composed of smaller sequences called boxes or elements.

19. A schematic view of a eukaryotic gene, and steps required to produce a protein product.

20. Adenine- and Thymine-rich consensus In E.coli TATAAT is the consensus sequence TATA or Pribnow box. General Transcription Factor (GTF) binds to TATA box Facilitate the binding of RNA pol II

21. Eukaryotic gene promoter consensus sequences.

22. A. Eukaryotic general transcription factors (CTF, SP1, TFIID) bind to consensus sequences found in promoters for RNA polymerase II . Additional general transcription factors (TFIIs) are required for assembly of the initiation complex and recruitment of polymerase. B. Enhancer stimulation of RNA polymerase II .

23. Prokaryote

24. Transcribed region contains Introns and Exons. Intron= Do not contain coding sequence for proteins. Exons= Carrying the coding sequence for proteins. The first RNA form produced is heterogeneous nuclear RNA.

25. Modification of hnRNA A cap is added at the 5’ end (cap sidt) Poly-A tail added to the 3” end. Introns are removed by a process called splicing to produce the mature mRNA.

27. Rho-independent termination of transcription. A. DNA template sequence generates a self-complementary sequence in the RNA. B. Hairpin structure formed by the RNA. “N” represents a non-complementary base.

41. (1) Pre-mRNA combines with snRNPs and other proteins to form a spliceosome. (2) Within the spliceosome, snRNA base-pairs with nucleotides at the ends of the intron. (3) The RNA transcript is cut to release the intron, and the exons are spliced together; the spliceosome then comes apart, releasing mRNA, which now contains only exons.

47. Translation - Initiation A E Large subunit P Small subunit fMet UAC GAG...CU -AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA- AT GCA...T AAAAAA 5’ mRNA 3’

48. Translation - Elongation A E Ribosome P UCU Arg Aminoacyl tRNA Phe Leu Met Ser Gly Polypeptide CCA GAG...CU -AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA- AT GCA...T AAAAAA 5’ mRNA 3’

49. Translation - Elongation Aminoacyl tRNA A E Ribosome P Phe Leu Met Ser Gly Polypeptide Arg UCU CCA GAG...CU -AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA- AT GCA...T AAAAAA 5’ mRNA 3’

50. Protein Synthesis ANYTHING ACID AMINE C O OH C N H H H C HO H C H O C N H H H C H H C H O OH C N H H H C HO H Serine C H O OH C N H H H C H H Alanine H C O OH C R N H H Amino Acid H 2 O

51. Translation - Elongation A E Ribosome P CCA Arg UCU Phe Leu Met Ser Gly Polypeptide GAG...CU -AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA- AT GCA...T AAAAAA 5’ mRNA 3’

52. Translation - Elongation A E Ribosome P Aminoacyl tRNA CGA Ala CCA Arg UCU Phe Leu Met Ser Gly Polypeptide GAG...CU -AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA- AT GCA...T AAAAAA 5’ mRNA 3’

53. Translation - Elongation A E Ribosome P CCA Arg UCU Phe Leu Met Ser Gly Polypeptide CGA Ala GAG...CU -AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA- AT GCA...T AAAAAA 5’ mRNA 3’

54. Transcription And Translation In Prokaryotes 3’ 5’ 5’ 3’ Ribosome Ribosome 5’ mRNA RNA Pol.

56. Reverse transcriptase