lecture 8/27 molecular

Question 1

What makes up a splicesosome?

Answer 1

it is made up of

Different types of snRNA called u1,u2,u4,u5,u6

Question 2

What is human factor VIII gene?

Answer 2

Blood clotting gene defect most assocated with hemophillia

misplacement results in stop codon or framshift muation.

sex chromal recessive

Question 3

What does the binding of the activator protein cause?

Answer 3

It causes DNA it fold upon itself and binds to the mediator and it binds to the enhancer site on DNA

Question 4

What are SR proteins?

Answer 4

Are thought to be the first identifiers of exon and intron boundiers

Also hnRNP helps define introns

Question 5

How does 5’ capping work?

Answer 5

• As soon as mRNA has reached around 25 nucletides long its is capped

1. Dephosphorlayte 1 st nucleotide
2. add Guanine Mono Phosphate in reverse linkage (5’ to 5’)
3. Methyl group added to guanosine

Question 6

What are the steps involved in eukaroytic mRNA processing prior to leaving the nucleus?

Answer 6

1. 5’ capping
2. 3 polyadenylation
3. RNA splicing

Question 7

What percent of mutations cause changes in splice site sequences?

Answer 7

10%

single nucleotide changes can cause:

• Exon skip
• cryptic splice
• new exon incorporated

Question 8

What is required for poly A tail to form?

Answer 8

• 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

Question 9

What is the function of the 5’ cap?

Answer 9

Protects ends

differentiate itself from noncoding RNAs

Question 10

What is the clinical definition of exosome?

Answer 10

• 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

Question 11

What is one big picture idea that arises from splicing?

Answer 11

shows how complex we are, one specfic exon can code for 40 different proteins depending on it is spliced

Question 12

What specialized proteins remove helical tension?

Answer 12

topoismerases

Question 13

When rna is spliced what happens to its exons/.

Answer 13

• either
• all exons can all be expressed,
• Exons skip
• or cryptic splice site selection can occur
  
  • only a portion is copied

Question 14

As polymerase moves through the DNA strand what does it generate (other than DNA/RNA) ?

Answer 14

It generates postive superhelical tension

(negative relieves tension)

Question 15

In general, true or false. Prokaroytic a single mRNA can code for multiple proteins

Answer 15

TRUE

Question 16

Name one example of gene that is alternatively spliced?

Answer 16

Tropomyosin. four genes responsible for 40 different tropomyosin isotypes

Question 17

What are conserved sequences for splicing?

Answer 17

5’- AG |GGU ………………….A…………………….AG| G -3’

5’ G a (1st geen in exon) binds to A tail

Question 18

What is an exosome?

Answer 18

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

Question 19

What is the simple way that RNA splicing is done?

Answer 19

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

Question 20

in general, true or false eukaryotic mRNA codes for multiple proteins

Answer 20

FALSE

in general NO but alternative splicing can make 1 mRNA into a multitude proteins

Question 21

When during RNA processing is mRNA capped?

Answer 21

As soon as it leaves the RNA polymerase.

Question 22

What does RNA splicing remove?

Answer 22

Introns

Question 23

What kind of RNA processing do prokaryotes go through?

Answer 23

they actually dont go through any. They head directly into transcription

Question 24

What is added to the 3’ end of Eukaroyotic DNA?

Answer 24

Poly A tail

Question 25

True or False splicesome requires ATP hydrolysis?

Answer 25

TRUEEEEEEEE