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The Synthesis and Processing of RNA

The Synthesis and Processing of RNA. RNA. Single stranded Nitrogenous bases -A:U C:G -Unlike DNA, RNA has uracil instead of thymine. Synthesis . RNA synthesis is directed by a DNA template which is described through three phases : intiation , elongation, and termination. . Three phases.

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The Synthesis and Processing of RNA

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  1. The Synthesis and Processing of RNA

  2. RNA Single stranded Nitrogenous bases -A:U C:G -Unlike DNA, RNA has uracil instead of thymine

  3. Synthesis • RNA synthesis is directed by a DNA template which is described through three phases : intiation, elongation, and termination.

  4. Three phases • Initiation: RNA polymerase binds to the promoter region ,specifically at TATA box, unzipping the DNA into two strands. • Transcription factors bind to the TATA box triggering the binding of RNA Polymerase to DNA. • Elongation: RNA polymerase begins to transcribe the DNA in 3’->5’ direction until reaches termination site. • Termination: RNA reaches termination site

  5. Alteration of mRna ends • 5’ GTP (guanine nucleotide with two phopshategroups)cap added to the 5’ end of mRNA. Capping provides protection and stability exiting the nucleus. • Poly A tail(200 adenine nucleotides) is attached to the 3’ end serving same purpose as 5’ cap, providing protection as well for mobility across the cytoplasm • Protection for mRNA against enzymes

  6. RNA splicing • RNA splicing- removes noncoding segments from mRNA. • A transcribed segement contains exons(coding regions) and introns (non-coding regions). snRNP’s (small nuclear ribonucleo proteins) delete the introns and splice the exons. • Enzyme for RNA splicing- Spliceosomes.(Made from snRNP’s)

  7. Alternative Splicing • Removing introns out the RNA transcript produces different pre mRNA’s from the same transcript, coding for various proteins.

  8. Jeopardy

  9. What's the enzyme that unwinds DNA called? A) RNA polymerase B) DNA ligase C) reverse transcriptase D) DNA helicase Answer: d

  10. Alternative RNA splicing A) is a mechanism for increasing the rate of transcription. B) can allow the production of proteins of different sizes from a single mRNA. C) can allow the production of similar proteins from different RNAs. D) increases the rate of transcription. E) is due to the presence or absence of particular snRNPs. ANSWER: B

  11. What happens in elongation What happens in elongation A) DNA is transcribed into RNA b) poly a tail is added C) promoter is added D) RNA is transcribed into DNA It's a trick question a and d are similar ANSWER: A

  12. What direction does RNA transcribe in? 5’ --- 3’

  13. Nucleus Where does transcription occur occur in eukaryotes?

  14. what binds to DNA and assembles nucleotides into a strand that is complementary to the DNA template? RNA polymerase binds to DNA sequence

  15. How is the DNA template useful for RNA? DNA template is the blueprints for RNA. It helps assemble the RNA sequence

  16. What's the purpose of 5' GTP cap and poly A tail To protect the mRNA from enzymes in the cytoplasm.

  17. What step and where is the main site of transcriptional regulation and thus control of gene expression in general Initiation ; the promoter region is the main site of transcriptional regulation and thus control of gene expression in general

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