sparknotes
Post-Transcriptional RNA Processing
Terms
3' Splice site
-
One of the conserved sequences of an intron. Contains an adenine next to a
guanine base at the 3' end of an intron.
5' Capping
-
One post-transcriptional modification made in the cell nucleus. The addition of
a GTP molecule to the 5' end of a primary RNA transcript forming a 5'-5'
linkage between the two.
5' Splice site
-
One of the conserved sequences of an intron. Contains an guanine next to a
uracil base at the 5' end of an intron.
Alternative splicing
-
One of two forms of splicing in which splicing reactions other than those
between two adjacent intron sequences occur. Can be either trans-splicing
or exon-exclusion splicing.
Branch point A
-
One of the conserved sequences of an intron. Contains an adenine base
located approximately 30 nucleotides from the 3' end of an intron. Involved in
the first step of primary RNA transcript splicing.
Exon
-
Sequences that are preserved in primary RNA transcript splicing that will be
translated into proteins in the cell cytoplasm.
Guanyl transferase
-
The enzyme responsible for catalyzing the reaction that produces the 5' cap
through the addition of a GTP molecule to the 5' end of a primary RNA
transcript.
Intron
-
Non-protein coding sequences of a primary RNA transcript that are removed
and degraded during primary RNA transcript splicing.
Lariat structure
-
Term given to describe the structure of the intron-containing products of the
first and second steps of primary RNA transcript splicing. Contains a
lasso-like loop in which the 5' end of the intron is linked to the branch
point A through a phosphodiester linkage.
Mature messenger RNA
-
Term given to primary RNA transcripts that have undergone appropriate post-
transcriptional modifications and are ready for transport into the cell
cytoplasm for translation into proteins.
Poly A tail
-
One post-transcriptional modification made in the cell nucleus. A string of up
to 500 adenines added to the 3' end of primary RNA transcripts. Addition
catalyzed by the enzyme poly (A) polymerase that recognizes the sequence AAUAAA.
Primary RNA transcript
-
The product of eukaryotic DNA
transcription. RNA
containing introns
and exons.
RNA splicing
-
A two-step reaction in which introns are removed from a primary RNA
transcript and exons are joined together to form mature mRNA.
Small nuclear ribonucleoprotein
-
Protein components of the spliceosome that is responsible for helping in the
splicing reaction of primary RNA transcripts.
Spliceosome
-
The large, multi-component protein complex that mediates the splicing
reaction of primary RNA transcripts.
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