pack Flashcards
(19 cards)
What is RNA processing?Why does it happen?
The steps by which pre-mRNA is turned into mature mRNA so it can be ready to go to the cytoplasm and get translated.
What are the steps of RNA processing?
RNA capping
Polyedylnation
splicing
RNA editing
What happens in capping?What does it do to the mRNA?
Happens: 7-methylgunaosine cap will be added to the 5’ end.
It does: This will help the mRNA to stablize.
And acts as the ribosomal binding site.
(the size limit gets capped bc of the ribosomes that are binding)
What happens in polyadenylation?
Happens: adenosine is added to the 3’ end.
It does: Stablizes the mRNA and helps it get transported to the cytoplasm.
(bc poly is more than 2, so 3’ end) (helps it get transported bc there are a lot of A’s so they look like a train)
What happens during splicing? What is responsible for splicing?
Happens: Spliceosomes (snRNA + protein) remove introns and the two adjacent exons are joined togther.
What is alternative splicing?
Removal of introns can cause a different varity of sequences depending on how the exons where joined.
What is the alternative splicing of a-tropomyosin?
a-tropomyosin is contained in different structures in the body, but each mRNA sequence is different due to alternative splicing.
What is an example of alternative splicing in antibodies?
Two different antibodies (IgM and IgD) are produced from the same pre-mRNA due to alternative splicing.
What is an example of alternative splicing gone wrong?
improper splicing of b-globin causes b-thalasemia
What is systemic lupus erythematosus and what is its relation to alternative splicing? What are some of the symptoms?
It is an autoimmune disease that creates antibodies against various structures of the body.
Relation: Creates an antibody against splicesome which affects the splicing.
symptoms: fever, joint pain, IMPORTANT: butterfly rash
What is Hutchinson-Gilford Progeria Syndrome? How is it caused? what is its signficance?
Cause: Defect in the alternative splicing of Lamin-A which produces abnormal Lamin A.
Effect: Structural abnormalities in the nucleus which causes problems in the DNA repair which in turn allows for more mutations.
What is RNA editing?
It is: Changes in the sequence of mRNA by modification,insertion, and deletion.
What are the 3 major modifications in RNA editing?
1. Cytidine –> uradine (c to u)
Catalyzed by: Cytidine deaminase
2. adenosine to inosine (a to I)
Catalyzed by: adenosine deaminase
3. Guide RNA (gRNA) which inserts or deletes uridine.
What is the the most common form of RNA editing in humans?
A to I
What does inosine act as?
guanine
What are some of the effects of RNA editing?
Alter the splicing of mRNA and the ability of the edited mRNA to get translated.
What are the steps of guide RNA editing?
- gRNA binds to the mRNA
- Creates a cleave using endonuclease to be able to edit.
- addition of uradine via Tutase or removal via exouase.
- Seals the cleave using ligase
What is an example of RNA editing? b-100
Same pre-mRNA in the liver and intestine produces a different protein due to C to U RNA editing
Intestine: b-48
liver: b-100
What are some ways that RNA editing can be used clinicaly for treatments?
Cns disorders:Serotonin 2C receptors
A to I can affect the response of potassium voltage-gated channel subfamily A member 1 to certain drugs.
Drugs for inhibiting RNA editing enzymes.
