1. Regulatory RNAs

2. Bacterial sRNAs bind to mRNAs and trigger degradation or regulate translation

3. Riboswitches and attenuation are mechanisms to control gene expression in bacteria Organization of a riboswitch

4. Example: a SAM riboswitch Termination of transcriptionRepression of translation initiation

5. Example: a SAM riboswitch Transcriptional terminator

6. Examples of riboswitches and their metabolites

7. Attenuation is used in bacteria to regulate transcription of biosynthetic genes The leader peptide contains trp amino acids

8. Attenuation is used in bacteria to regulate transcription of biosynthetic genes

9. Bacterial defense against viruses: The CRISPR system CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats Organization of a CRISPR locus

10. Organization of CRISPR-associated genes in bacteria CRISPR locus

11. Acquisition of spacer sequences PAM: protospacer adjacent motif

13. Processing of CRISPR RNA and its antiviral action E.coliP. furiosus

16. Gene-editing using the CRISPR-Cas9 system Animation

17. In eukaryotes short RNAs are generated by different mechanisms than sRNAs in bacteria RISC: RNA-induced silencing complex

18. The PIWI-interacting RNA (piRNA) system is thought to silence transposons by passively acquiring and expressing transposon sequences

19. In eukaryotes short RNAs are generated by different mechanisms than sRNAs in bacteria RISC: RNA-induced silencing complex

20. Pre-microRNAs can form from various regions of a transcript

21. Structures of pre-microRNAs in Caenorhabditis

22. General structure of a primary microRNA and processing sites

23. Processing of pri-microRNAs by Drosha in the nucleus

24. Dicer processes microRNAs in the cytoplasm

25. Argonaute cleaves mRNAs after complementary base pairing of its guide RNA

26. In eukaryotes short RNAs are generated by different mechanisms than sRNAs in bacteria RISC: RNA-induced silencing complex

27. Centromeric silencing in S. pombe involves RNAi

28. Short interfering RNAs can be copied by an RNA- dependent RNA polymerase to amplify the inhibitory effect

29. Repressing gene expression by RNAi in Caenorhabditis

30. X-chromosome inactivation is initiated by expression of the Xist gene from the X-chromosome inactivation center (Xic)

31. Visualizing the Xist lncRNA (a) and the acetylation state of one of the X-chromosomes (b)

32. Calico cats have patch-colored fur due to expression of different X-chromosome alleles