Chapter 17: Non-Coding RNAs in Genetics

Non-Coding RNAs (ncRNAs)

RNA molecules that do not code for proteins.

Gene Estimates

Thousands to tens of thousands of ncRNA genes.

Transcription Ratio

80% ncRNAs, 20% mRNAs in human cells.

Binding Interactions

ncRNAs bind to DNA, other RNAs, and proteins.

Scaffold Function

ncRNA binds multiple proteins together.

Guide Function

ncRNA directs proteins to specific cellular sites.

Alteration of Protein Function

ncRNA modifies protein structure and stability.

Ribozyme

RNA with catalytic activity.

Blocker

ncRNA prevents cellular processes from occurring.

Decoy

ncRNA sequesters another ncRNA.

Long Non-Coding RNAs (lncRNAs)

ncRNAs longer than 200 nucleotides.

Small Regulatory RNAs

Short ncRNAs less than 200 nucleotides.

MicroRNAs

Small RNAs typically 20-25 nucleotides long.

HOTAIR

ncRNA that alters chromatin structure.

HOTAIR Gene Location

Located on human chromosome 12.

HOTAIR Length

2.2-kb-long ncRNA.

Polycomb Repressive Complex 2 (PRC2)

Complex involved in transcriptional repression.

Lysine Specific Demethylase 1 (LSD1)

Enzyme that works with PRC2.

RNA Silencing

Process that reduces mRNA levels.

Petunia Experiment

Study on flower color using RNA techniques.

Sense RNA

RNA that can inhibit mRNA function.

Antisense RNA

RNA that binds to and inhibits mRNA.

C. elegans

Model organism for RNA injection studies.

mex-3 mRNA

Abundant mRNA in early C. elegans embryos.

In Situ Hybridization

Technique to detect specific RNA in cells.

RNA Polymerase

Enzyme that synthesizes RNA from DNA.

Cloned Genes

Genes replicated for experimental purposes.

RNA interference (RNAi)

Process where double-stranded RNA silences mRNA.

Double-stranded RNA

RNA that enhances silencing of target mRNA.

MicroRNAs (miRNAs)

Endogenous ncRNAs regulating gene expression.

Small interfering RNAs (siRNAs)

Exogenous ncRNAs that silence specific mRNAs.

RISC

Complex that mediates RNA interference effects.

Processing body (P-body)

Cellular structure where RISC-mRNA complex resides.

Argonaute

Protein that cleaves mRNA in RISC.

Gene regulation

Control of gene expression levels in cells.

CRISPR-Cas system

Bacterial defense mechanism against foreign DNA.

CRISPR locus

Chromosomal region containing repeated sequences.

Spacer acquisition

Insertion of bacteriophage DNA into CRISPR.

tracrRNA

Non-coding RNA that aids in CRISPR function.

crRNA

Guide RNA derived from pre-crRNA in CRISPR.

Endonuclease

Enzyme that cuts DNA strands.

Adaptation phase

Initial phase where spacers are acquired.

Expression phase

Phase where CRISPR components are produced.

Interference phase

Phase where target DNA is cleaved.

Bacteriophage

Virus that infects bacteria.

Transposable elements

DNA sequences that can change positions.

Nobel Prize

Award for significant scientific discoveries.

Chromatin modifications

Changes in DNA structure affecting gene expression.

piRNAs

Small RNAs involved in transposon regulation.

Potent silencing

Strong inhibition of mRNA translation.

Partial complementarity

Mismatch between miRNA and target mRNA.

Complete degradation

Total breakdown of target mRNA.