1. GENETICS ESSENTIALS Concepts and Connections SECOND EDITION GENETICS ESSENTIALS Concepts and Connections SECOND EDITION Benjamin A. Pierce © 2013 W. H. Freeman and Company CHAPTER 10 From DNA to Proteins: Transcription and RNA Processing

2. CHAPTER 10 OUTLINE 10.1 RNA, Consisting of a Single Strand of Ribonucleotides, Participates in a Variety of Cellular Functions, 258 10.2 Transcription Is the Synthesis of an RNA Molecule from a DNA Template, 260 10.3 The Process of Bacterial Transcription Consists of Initiation, Elongation, and Termination, 264 10.4 Many Genes Have Complex Structures, 268 10.5 Many RNA Molecules Are Modified after Transcription in Eukaryotes, 270

4. 10.1 RNA, CONSISTING OF A SINGLE STRAND OF RIBONUCLEOTIDES, PARTICIPATES IN A VARIETY OF CELLULAR FUNCTIONS The structure of RNA Primary structure Secondary structure

5. The structure of RNA Classes of RNA Ribosomal RNA – rRNA Messenger RNA – mRNA Transfer RNA – tRNA Small nuclear RNAs – snRNAs Small nuclear ribonucleoproteins – snRNPs Small nuclear RNAs – snoRNAs Small cytoplasmic RNAs – scRNAs MicroRNAs – miRNAs Small interfering RNAs – siRNAs 10.1 RNA, Consisting of a Single Strand of Ribonucleotides, Participates in a Variety of Cellular Functions

6. 10.2 TRANSCRIPTION IS THE SYNTHESIS OF AN RNA MOLECULE FROM A DNA TEMPLATE The template: The transcribed strand: template strand

7. 10.2 TRANSCRIPTION IS THE SYNTHESIS OF AN RNA MOLECULE FROM A DNA TEMPLATE The template: The transcription unit A promoter RNA-coding sequence Terminator

8. The substrate for transcription: Ribonucleoside triphosphates – rNTPs added to the 3′ end of the RNA molecule. The transcription apparatus: Bacterial RNA polymerase: five subunits made up of the core enzyme: The sigma  factor: binding to the promoter when transcription starts. Core enzyme +  factor = holoenzyme 10.2 Transcription Is the Synthesis of an RNA Molecule from a DNA Template

9. Initiation The substrate for transcription: Ribonucleoside triphosphates – rNTPs added to the 3′ end of the RNA molecule. The transcription apparatus: Eukaryotic RNA polymerases 10.2 Transcription Is the Synthesis of an RNA Molecule from a DNA Template

10. 10.3 THE PROCESS OF BACTERIAL TRANSCRIPTION CONSISTS OF INITIATION, ELONGATION, AND TERMINATION Initiation Bacterial promoters: Consensus sequences: sequences that possess considerable similarity. -10 consensus : 10 bp upstream of the start site. Pribnow box: 5 TATAAT 3 3 ATATTA 5 - 35 consensus sequence: TTGAC

11. Initiation Initial RNA synthesis: No primer is required. The location of the consensus sequence determines the position of the start site. (next slide) Elongation RNA elongation is carried out by the action of RNA polymerase. 10.3 The Process of Bacterial Transcription Consists of Initiation, Elongation, and Termination

13. Termination Rho-independent termination: hairpin structure formed by inverted repeats, followed by a string of uracils. Rho-dependent termination 10.3 The Process of Bacterial Transcription Consists of Initiation, Elongation, and Termination

14. 10.4 MANY GENES HAVE COMPLEX STRUCTURES Gene Organization The concept of colinearity and noncolinearity

15. GENE ORGANIZATION Introns Exons

16. THE CONCEPT OF THE GENE The gene includes DNA sequence that codes for all exons, introns, and those sequences at the beginning and end of the RNA that are not translated into a protein, including the entire transcription unit―the promoter, the RNA coding sequence, and the terminator.

17. 10.5 RNA MOLECULES The structure of messenger RNA A mature mRNA contains 5′ untranslated region (5′ UTR, or leader sequence) Shine–Dalgarno sequence in bacteria Protein-coding region 3′ untranslated region

18. 10.5 MANY RNA MOLECULES ARE MODIFIED AFTER TRANSCRIPTION IN EUKARYOTES The addition of the 5′ cap: A nucleotide with 7-methylguanine; 5′-5′ bond is attached to the 5′ end of the RNA. The addition of the poly(A) tail: 50 ~ 250 adenine nucleotides are added to the 3′ end of the mRNA.

19. 10.5 MANY RNA MOLECULES ARE MODIFIED AFTER TRANSCRIPTION IN EUKARYOTES Alternative splicing:

20. THE COMPLETE PROCESS

21. THE STRUCTURE OF TRANSFER RNA Rare modified RNA nucleotide bases Ribothymine Pseudouridine Common secondary structure―the cloverleaf structure Anticodon

22. THE STRUCTURE AND PROCESSING OF RIBOSOMAL RNA Large ribosome subunit Small ribosome subunit

23. SMALL INTERFERING RNAs AND MicroRNAs RNA interference: limits the invasion of foreign genes and censors the expression of their own genes Types of small RNAs Processing and function of microRNAs