BIOL 305- mRNA Types

noncoding RNA definition:

RNA which does not code for a protein

Large mRNA subgroups:

1. NATS

2. LINKs

NATS function:

Natural Antisense mRNA’s which regulate their compliments by binding to them

LINKs function:

Large Intragenic mRNA’s which do not have genes and modify chromatin to regulate transcription

Small mRNA’s:

1. gRNA

2. snoRNA

3. siRNA

4. miRNA

5. circRNA

gRNA function:

edit RNA by removing or adding U’s where improper base pairing is evident

gRNA method for removing U’s:

exonuclease removes the U and ligase repairs the backbone break

gRNA method for adding U’s:

TUTase adds U’s after exonuclease activity is done

snoRNA function:

modify bases in the RNA to produce rRNA

snoRNA target for base changes:

1. 2’ OH methylation of ribose sugar

2. Base rotation of Uridine into Pseudouridine

snoRNA sequence involved in methylation:

C/A box

snoRNA sequence involved in pseudouridation:

H/ACA box

siRNA function:

modifies chromatin structure

miRNA function:

blocks translation

miRNA and siRNA are produced from the _______ process

RNA interference

RNA interference is what?

the degradation of double stranded RNA transcripts into guide strands by dicer enzyme

dicer function in RNAi:

recognizes and cuts dsRNA into guide and passenger strands

guide strand function in RNAi:

incorporated into the RISC complex so RISC can bind to target RNA for degradation

RISC function in RNAi:

contains argonaut which will cut the target RNA

amplification definition:

the property of guide strands to bind to RNA, allowing them to be transcribed into dsRNA to produce more siRNA

siRNA’s 3 enzyme capable of modifying chromatin structure:

1. Swi6

2. Dicer

3. RITS complex

Swi6 enzyme function:

binds to OTR region in centromere to form heterochromatin

Dicer enzyme funciton:

cuts dsRNA to form siRNA which are incorporated into RITS complex

RITS enzyme complex function:

Recruited to the OTR which recruits histone methyl transferase to methylate H3 to recruit Swi6

miRNA function in plants:

promotes RNA degradation to block gene expression

miRNA function in animals:

prevents translation to block gene expression

miRNA is produced from _____ by _______

pri-miRNA/ Drosha DGCR8 and dicer

p-body function:

destroys or inhibits translation of RNA bound to an miRNA

miRNA and siRNA similarities:

1. Associated with dsRNA

2. Processed by dicer

3. Have argonaut

4. Degrade RNA

circRNA function:

common machinery in splicing events