BIO 190- *Ch. 11* Expression of Genetic info via non coding RNAs (ncRNA)

what can nRNAs bind to

DNA (through complimentary base pairing)

RNA (through complimentary base pairing)

Protein (through covalent, hydrogen, or ionic bonds)

Small Molecules (through covalent, hydrogen, or ionic bonds)

list the functions for ncRNA

scaffold

guide

alter protein shape

ribozyme

Blocker

Decoy

template for dna synthesis

what is a ribozyme (rRNA)

catalyzes peptide bonds during translation

scaffold

binds to multiple components such as proteins act as a scaffold for formation of a complex

guide in ncRNAs

guide one molecule to a specific location in the cell, for example guiding a protein to a particular site on DNA

alteration of protein function or stability

binding of ncRNA can affect the ability of the protein to be a catalyst the ability of the protein to bind other molecules or the proteins stability

what is the blocker in ncRNA

physically prevents or blocks a cellular process from happening for example blocks the binding of a ribosome thereby inhibiting translation

what is a decoy in ncRNA

recognize other ncRNAs and sequester them preventing them from working

blocker vs decoy

blocker binds a molecule that is not an ncRNA and decoy binds to an ncRNA

What are telomeres

tips of chromosomes (protection against getting tangled)

what does the enzyme telomerase do

maintains the length of telomeres, which are protective caps at the ends of chromosomes. Telomeres shorten with each cell division, and if they become too short, the cell can stop dividing or die. Telomerase counteracts this process by adding DNA sequences to the telomeres, preventing them from shortening and enabling cells to divide more times.

allows the strand to be synthesized to the full length of the top strand

what does HOTAIR do

a ncRNA in humans and other mammals that regulates transcription by forming a scaffold that binds 2 protein complexes and guides them to particular genes

"are the nucleosomes tight (gene is hidden) or spaced out"

the protein complexes covalently modify histones and these modifications silence the target genes

HOTAIR gene expression / transcription

end result:

ncRNA binds to:

ncRNA functional role:

end result: guides proteins to genes which change histones to inhibit/ silence transcription

ncRNA binds to: protein

ncRNA functional role: scaffold guide

DNA replication (telomerase)

end result:

ncRNA binds to:

ncRNA functional role:

end result:prevention of chromosome shortening during each round of cell division

ncRNA binds to: end of DNA

ncRNA functional role:

1. guide telomerase/ DNA polymerase to the end of chromosomes

2. template for DNA synthesis: lengthens DNA strand and moves space for a primer

micro-RNA (miRNA) or siRNAs

end result:

ncRNA binds to:

ncRNA functional role:

end result: inhibits translation of mRNA into protein

ncRNA binds to: messenger RNA (mRNA)

ncRNA functional role: blocker

what is RNA interface

when microRNA or siRNA binds to mRNA and blocks translation

what are microRNAs

ncRNAs that are transcribed from endogenous eukaryotic genes

what are small interfering RNAs (siRNAs)

come from exogenous source- viruses that infect a cell

what are Signal recognition particles (SRP)

end result:

ncRNA binds to:

ncRNA functional role:

end result:targeting of proteins with a signal sequence to their correct destination, most commonly the endoplasmic reticulum (ER) membrane.

ncRNA binds to: ER sorting signal in a growing protein

ncRNA functional role:

1. Guide: guides ribosomes to ER surface

2. Alter protein shape: of ER and polypeptides feed into ER

what does the CRISPR-Cas system do

provides defence agaiant bacteriophages and transposons

what do Cas 9 Cas 1 and Cas 2 do

cut phage DNA

what are CRISPR

end result:

ncRNA binds to:

ncRNA functional role:

end result: cut up the phage DNA (including viral DNA)

ncRNA binds to: tracer RNA binds to crisper RNA and cas 9

ncRNA functional role:

1. scaffold: expression phase

2. guides cas9 to remaing phage DNA and cuts up DNA

(Inference phase)

the CRISPR- cas system 3 phases

adaptation, expression, and interference

CRISPR- cas system adaptation phase

occurs after the bacterial cell has been exposed to the bacteriophage

what can bind to ncRNAS

DNA, RNA, proteins, small molecules

what are the 2 functions of TERC (the RNA component of telomerase)

a guide: (helps telomerese recognize and bind to ends of chromosomes)

and a template

name 3 functions of HOT AIR

decoy

scaffold

guide

during RNA interference what binds to an mRNA to inhibit translation

single strand of miRNA or single strand of siRNA

name 4 functions of SRP (single recognition particle)

pauses translation of polypeptides that have an ER signal sequence , binds to SRP receptor in ER membrane, docks the ribosome over a channel, hydrolyzes GTP to promote SRP release from the SRP receptor

TERC is involved in

elongation

HOTAIR is involved in

chromatin structure and transcription

CRISPR RNA is involved in

bacterial adaptive immunity

siRNA is involved in

post transcriptional gene silencing

what does Cas 1/2/9 do

cleaves up viral DNA into pieces during the adaption phase

what does tacrRNA do

scaffolds Cas9 to piece of cRNA

what does crRNA do

guides Cas 9 to the target viral DNA