Non-Coding RNAs

What does ncRNA stand for?

non-coding RNA

What does RNAi stand for?

RNA interface

What are the six functions of ncRNA?

scaffold, guide, alter protein function, ribozyme, blocker, decoy

What are the four ways ncRNA bind?

RNA-DNA, RNA-RNA, RNA-Protein, RNA-Small Molecule

What is RNA interference?

phenomenon which double-stranded RNA caused silencing of mRNA

How does double stranded RNA form?

mRNA binding to antisense RNA

How does ncRNA bind to RNA or DNA?

complimentary base pairing

How does ncRNA bind to protein or small molecules?

secondary structures

What are the two kinds of RNAi?

microRNA, short interfering RNA

Where does microRNA come from?

transcribed from endogenous eukaryotic genes

Where does short interfering RNA (siRNA) come from?

originate from exogenous sources

Scaffold

ncRNA binds a group of proteins

Guide

ncRNA guides molecule to specific location in cell

Alter protein function

ncRNA binds protein and alters structure, stability, binding partners, or activity

Ribozyme

RNA molecule with catalytic function

Blocker

ncRNA physically prevents or blocks cellular process from happening

Decoy

ncRNA recognizes another ncRNA and sequesters it

What is Dicer?

an enzyme that cuts pre-microRNA and pre-siRNA to form a 20-25 nucleotide length double-stranded RNA

What does RISC stand for?

RNA-induced silencing complex

How is RISC formed?

microRNA or siRNA is recognized by a protein that associates with other proteins to form it

What happens to the double stranded RNA when RISC is formed?

One of the RNA strands is degraded, the other binds to complimentary mRNA (which is later degraded)

What is RNAi found in?

most eukaryotic species

What does not have RNAi?

bacteria

Why is RNAi important for humans?

microRNA is involved with gene regulation

Why is RNAi important for plants?

siRNA defends against viruses

How does the CRISPR-Cas system help bacteria?

provides defense against bacteriophages

What does CRISPR-Cas do to bacteriophage?

saves part of the phage genome to attaxk future viruses when they invade

Where are phage DNA sequences stored?

in the bacterial chromosome at the CRISPR locus site

What occurs during the adaptation phase?

bacteriophage DNA enters cell and is then cut by Cas proteins, cut pieces are inserted as spacers

What occurs during the expression phase?

crispr, tracr, and cas9 are expressed, crRNA and tracrRNA form complex, complex binds to cas9 via tracrRNA

What occurs during the interference phase?

tracrRNA-crRNA-cas9 complex binds to bacteriophage DNA via complimentary base p pairing, cas9 cleaves DNA and inactivates the DNA

What are spacers?

inserts of foreign DNA inside the Crispr gene

Crispr RNA

crRNA, acts as a guide that causes Cas9 to bind to bacteriophage DNA

tracrRNA

acts as a guide that causes tracrRNA-crRna to bind to a Cas9 protein

Cas9

endonuclease that makes double strand breaks in bacteriophage DNA

What aspect of the CRISPR-Cas system allows bacterial immunity to be inheritable by daughter cells?

spacers from past infections are passed on to the daughter cells