lecture 8/27 molecular Flashcards
What makes up a splicesosome?
it is made up of
Different types of snRNA called u1,u2,u4,u5,u6
What is human factor VIII gene?
Blood clotting gene defect most assocated with hemophillia
misplacement results in stop codon or framshift muation.
sex chromal recessive
What does the binding of the activator protein cause?
It causes DNA it fold upon itself and binds to the mediator and it binds to the enhancer site on DNA
What are SR proteins?
Are thought to be the first identifiers of exon and intron boundiers
Also hnRNP helps define introns
How does 5’ capping work?
- As soon as mRNA has reached around 25 nucletides long its is capped
- Dephosphorlayte 1 st nucleotide
- add Guanine Mono Phosphate in reverse linkage (5’ to 5’)
- Methyl group added to guanosine
What are the steps involved in eukaroytic mRNA processing prior to leaving the nucleus?
- 5’ capping
- 3 polyadenylation
- RNA splicing
What percent of mutations cause changes in splice site sequences?
10%
single nucleotide changes can cause:
- Exon skip
- cryptic splice
- new exon incorporated
What is required for poly A tail to form?
- CA sequence at the 3’ end of chromosome, signal that mrna needs to clipped w/ poly A tail
- 10-30 mucleotides down stream
- PAP poly adenosine polymerase
- poly a binding proteins = longer tail
What is the function of the 5’ cap?
Protects ends
differentiate itself from noncoding RNAs
What is the clinical definition of exosome?
- Exosome membrane bound cell present in all eukaryotic fluids
- Ex: blood, urinine,and cultured medium of cell cultures
- evolutionaryly conserved
- can be used to carry information from tissue to another
- biomarker
What is one big picture idea that arises from splicing?
shows how complex we are, one specfic exon can code for 40 different proteins depending on it is spliced
What specialized proteins remove helical tension?
topoismerases
When rna is spliced what happens to its exons/.
- either
- all exons can all be expressed,
- Exons skip
- or cryptic splice site selection can occur
- only a portion is copied
As polymerase moves through the DNA strand what does it generate (other than DNA/RNA) ?
It generates postive superhelical tension
(negative relieves tension)
In general, true or false. Prokaroytic a single mRNA can code for multiple proteins
TRUE
Name one example of gene that is alternatively spliced?
Tropomyosin. four genes responsible for 40 different tropomyosin isotypes
What are conserved sequences for splicing?
5’- AG |GGU ………………….A…………………….AG| G -3’
5’ G a (1st geen in exon) binds to A tail
What is an exosome?
Is a protein complex that cleans up damge RNAs “exonic” before they leaved nucleus.
Its core is rich in RNAases “nucleases” and chops up RNAs for recycling
What is the simple way that RNA splicing is done?
5’ end of intron recongizes internal Adenine
2-OH bond on 3’ end of exon attacks exons 5’ end.
intron forms lariot formation
DNA binds together
in general, true or false eukaryotic mRNA codes for multiple proteins
FALSE
in general NO but alternative splicing can make 1 mRNA into a multitude proteins
When during RNA processing is mRNA capped?
As soon as it leaves the RNA polymerase.
What does RNA splicing remove?
Introns
What kind of RNA processing do prokaryotes go through?
they actually dont go through any. They head directly into transcription
What is added to the 3’ end of Eukaroyotic DNA?
Poly A tail
True or False splicesome requires ATP hydrolysis?
TRUEEEEEEEE
