Chapter 10.1 FINALS

Question 1

What are the 5 types of RNA processing?

Answer 1

1. Cleavage (Endonuclease/Exonuclease) - cutting or splitting into smaller pieces
2. Splicing - removing junk parts called introns
3. 5’ Capping - adding a cap to the start
4. Polyadenylation - adding a tail to the end
5. Editing (Insertion/Deletion/Modification) - changing letters in the RNA
   *6. Nucleotide Modifications - chemical changes

Question 2

3 Main benefits of RNA processing?

Answer 2

1. Gene expression
2. Diversity (via splicing & editing)
3. Quality control

Question 3

RNA processing complexes contain?

Answer 3

Protein & RNA (ribonucleoproteins)

Question 4

Describe RNPs

Answer 4

1. Structural
2. Catalytic Activities (ribozymes)
3. Contain guide RNA that base pair with pre-RNA & guide the RNP to the correct place for processing

Question 5

What is tRNA & rRNA processing?

Answer 5

Start as long precurses → cut and trimmed into final form

Question 6

What are Ribonucleases?

Answer 6

They cleave RNAs into smaller parts. (exonuclease & endonuclease)
ex RNase III and RNase P

Question 7

RNase III

Answer 7

Cut double-stranded RNAs (endo)
Protein
Excision & trimming
Products: miRNA + siRNA

Question 8

RNase P

Answer 8

Cut single-stranded RNAs (endo)
Proteins (enhance activity) + RNA component (cut)
5’ end trimming

Question 9

tRNA and rRNA splicing catalyzed by?

Answer 9

tRNA - protein factors
rRNA - self-splicing

Question 10

CCA Sequence addition to tRNA

Answer 10

3’ end for amino acid attachment site
Added via CCA-adding enzyme (+ repair & maintenance)
No nucleic acid template
Addition catalyzed via nucleotide binding pocket (3 conformations)

Question 11

Nucleotide Modifications

Answer 11

On base or ribose sugar rings
Small: 1. Hydrogen atom addition
2. Nitrogen & Oxygen methylation
3. Selenium addition
Big: Threonine addition

tRNA: 80+ modifications (Guanosine methylation & methyl amino methyl group addition, selenium to uridine)

rRNA: 1. Ribose 2’-O-methylation
2. Pseudouridylation (extra hydrogen bonding capacity)

Question 12

snoRNA

Answer 12

Catalyze (1) Ribose methylation “box C/D snoRNAs” & (2) Uridine to pseudouridine “H/ACA snoRNA”
Guide enzymes to site in RNA to be modified
In nucleolus
Composition: introns of precursor mRNAs

Question 13

5’ Capping functions (6)

Answer 13

(1) elongation
(2) transcript termination
(3) mRNA processing
(4) binding site for exporting to cytoplasm
(5) direct initiation of protein synthesis
(6) protects 5’ end from degradation

Question 14

Enzymes & (3 stages of adding cap)

Answer 14

1. RNA 5’ triphosphate - catalyze removal of phosphate from 5’ end
   
   2. Guanyl transferase - attach guanosine monophosphate to end in 5’-5’ triphosphate linkage
   3. Guanine-7-methyl transferase - methylates the guanine