2.5 Coding and Non-coding RNA Flashcards
What was the nature of the defect that caused hemophilia in the family of Tsar Nicholas?
Defect in splice site caused inactivation of hemophilia gene. Point mutation.
What is the concept of collinearity and noncollinerity.
Suggests that a continuous sequence of nucleotides in DNA encodes a continuous sequence of amino acids in a protein.
What are euk genes? noncolinearity or colinearity?
Noncolinearity
How did we find out that euk genes were noncolinear?
By hybridizing DNA and mRNA
How did we find out that euk genes were noncolinear?
By hybridizing DNA and mRNA
Why are euk genes noncolinear?
The coding sequences (exons) of most euk genes are disrupted by noncoding introns.
What is the splicing mechanism for Group I introns?
self splicing
What is the splicing mechanism for Group II introns?
Self splicing
What is the splicing mechanism for Nuclear pre-mRNA introns?
Spliceosomal
What is the splicing mechanism for tRNA introns?
Enzymatic
What does a gene include?
- DNA seq that code for exons and introns. 2. Seq at the beginning and end of RNA that are not translated into a protein, including the entire transcription unit (promoter, RNA coding seq, terminator)
What is the structure of mRNA?
5’ UTR (where 5’ cap is), Protein coding region and 3’ untranslated region which is site if microRNA binding. (poly a tail)
The splicesome must know what in order to splice?
The consensus sequences on the 5’ and 3’
What does the addition of 5’ cap do?
Helps binding of ribosome to 5’ end of mRNA, increases mRNA
What does the addition of polyA tail do?
Increases stability of mRNA, helps binding of ribosome to mRNA.
What is the seq of events for splicing? 5 steps
- 5’ site recognized and brings proteins in to do cutting. 2. 5’ bent around and attache to A. 3. 3’ end cut. 4. intron released. 5. Exons spliced together.
Where does RNA splicing take place?
Within the spliceosome
What is nuclear organization?
intron removal, mRNA processing, and transcription take place at the same site in the nucleus.
Pertaining to alternative splicing, what does it depend on?
Where the 3’ cleavage site is
What is RNA editing?
Coding seq altered after transcription
What are guide RNAs?
Responsible for RNA editing. They change seq of a message POST transcriptionally, so that it is slightly modified . Thus making significant changes in amino acids.
When is mature euk mRNA produced?
When pre-mRNA is transcribed and undergoes sever types of processing
What two things do siRNAs and microRNAs have?
Dicer and RISC.
What does Dicer do?
Dicer cleaves dsRNA and pre-miRNA into short ds RNA fragments (siRNA and microRNA)
What is RISC?
RNA-induced silencing complex
What do siRNAs do?
Interfere with the expression of specific genes with complementary nucleotide sequenced by degrading mRNA after transcription. Preventing translation.
Which is more common? siRNA or microRNA?
siRNA
What is the origin of siRNA?
mRNA, transposon, or virus
What is the origin of miRNAs?
RNA transcribed from distinct gene
What is siRNA cleaved from?
RNA duplex or ssRNA that forms long hairpins
What is miRNA cleaved from?
ssRNA that forms short hairpins of dsRNA
What is the size of siRNA and miRNA?
same size, 21-25 nucleotides
What does siRNA inhibit through action?
Transcription
What does miRNA inhibit through action?
Translation
What is the target of siRNA?
genes from which they were transcribed
What is the target of miRNA?
Genes from other than those from which there were transcribed.
What are snoRNAs?
purpose is to modify other noncoding RNAs like the ribosome. Add mythel groups, not inhibiting but slightly changing
What regulatory role do snoRNAs play in?
Development
What is the structure of tRNA?
Rare modified RNA nucleotide bases (ribothymine and pseudouridine), the cloverleaf structure (2ndary structure), and anticodon
What do all tRNAs posses?
a common 2ndary structure, the cloverleaf structure.
What is the anticodon on tRNA?
Has 3 bases and interacts with a codon in mRNA. Determines which amino acid is attached to the acceptor arm
What is the acceptor arm in tRNA?
the site of attachment of amino acids to tRNA
What are tRNAs capable of?
self splicing
When is ribosomal RNA processed?
After transcription
What is CRISPR?
Prokaryotic noncoding RNA, function in defense against invasion of foreign DNAs and chops it up.
