Содержание
- 2. Genetic information is transferred from genes to the proteins they encode via a “messenger” RNA intermediate
- 3. Most genes have their protein-coding information interrupted by non-coding sequences called “introns”. The coding sequences are
- 4. The intron is also present in the RNA copy of the gene and must be removed
- 5. Splicing a pre-mRNA involves two reactions pre-mRNA intron branchpoint A
- 6. Splicing occurs in a “spliceosome” an RNA-protein complex (simplified) spliceosome (~100 proteins + 5 small RNAs)
- 7. RNA is produced in the nucleus of the cell. The mRNA has to be transported to
- 8. Pre-messenger RNA Processing cytoplasm nucleus cap poly(A) tail
- 9. Alternative splicing In humans, many genes contain multiple introns Usually all introns must be removed before
- 10. However, multiple introns may be spliced differently in different circumstances, for example in different tissues. Thus
- 11. Different signals in the pre-mRNA and different proteins cause spliceosomes to form in particular positions to
- 12. APOPTOSIS Alternative splicing can generate mRNAs encoding proteins with different, even opposite functions (programmed cell death)
- 13. Alternative splicing can generate tens of thousands of mRNAs from a single primary transcript Combinatorial selection
- 14. Examples of the potential consequences of mutations on splicing Mutations occur on the DNA (in a
- 15. Pathologies resulting from aberrant splicing can be grouped in two major categories Mutations affecting proteins
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