TXN II: RNA Processing Flashcards Preview

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Flashcards in TXN II: RNA Processing Deck (10)
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1
Q

3 Steps of RNA Processing

A
  1. Capping (cotranscriptionally) and polyadenylation

3. Splicing

2
Q

mRNA Capping

A

5’ to 5’ TRIphosphate bond. methyl cap marks RNA

  • gives stability
  • directs to cytoplasm
  • required for translation
  • marks as nonviral
3
Q

Cleavage and Polyadenylation

A
AAUAAA marks for cleavage
Poly (a) polymerase poops out long chain of A residues (no template needed)
This:
-marks mRNA as special
-speeds up translation
-stabilizes
4
Q

Protein Diversity and Polyadenylation?

A

Variations on where transcribed RNA is polyadenylated = different translation (different proteins)

5
Q

Spinal Muscular Atrophy

A

Motor Neuron degeneration. caused by mutation in SMN1 protein that inhibits snRNP assembly by splicing defects

6
Q

snRNP in RNA splicing

A

Recognize Splicing Signals (conserved nucleotide sequence) and holds RNA in place while splicing occurs, catalyzing the process

If there are insufficient numbers of snRNPs inefficient/incorrect splicing occurs which results in different proteins. This equals different function.

7
Q

Lariat Structure

A
  1. snRNP + branchpoint A form complex U2 which binds with 5’ G of INTRON + snRNP (complex U1).
  2. 3’-G at end of EXON 1 attacks 5’G of EXON 2
  3. Introns become lariat to be degraded while exons condensed. This is catalyzed by snRNPs U3 4 5
8
Q

Splice Variants

A

variants in proteins caused by variants in splicing can create crappy function. Associated with SNP.

9
Q

Auxillary Splicing Regulatory Elements

A

bind to places within intron/exon to promote or repress choice of splice site

10
Q

Beta-Thalassemia

A

Reduced beta globin

Caused by abnormal splicing because of mutation in normal splicing acceptor site and binds to cryptic splice site

B0 mutation:

  • exon 2 binds to cryptic site on intron instead of normal acceptor site on exon3
  • severe

1 B+:

  • Not as severe
  • exon 1 sometimes binds to cryptic site btwn. ex1 and ex2 but sometimes binds to acceptor site on ex2

1 B Hb E:
-new donor site in ex1