Lecture 21: Genome Editing and Biotechnology
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Refers to the development of new varieties, traits, or products through genetic engineering and editing of an organism genome
Biotechnology
What is an effective method to silence genes in organisms?
Using short interfering RNAs (siRNAs)
What are three characteristics that MicroRNAs and siRNAs have in common?
• 20-24 nucleotides long • processed from longer RNA precursors by Dicer-like ribonucleases • incorporated into RISC in which the small RNAs guide target gene repression
Through mRNA stability regulation, what are siRNAs involved in?
• defense against viruses • silencing transposons and transgenes
What is the fundamental difference between siRNAs and MicroRNAs?
siRNAs are processed from long double-stranded RNAs miRNAs are processed from single RNA molecules that include an imperfect stem-loop secondary structure
What types of gene silencing do siRNA mediate? and microRNAs?
microRNA: post-transcriptional gene silencing siRNA: post-transcriptional and transcriptional gene silencing
What is the preferred technology for gene silencing in polyploid organisms?
RNAi
Why would we inhibit undesirable genes in-species mode? (in crops)
To inhibit the growth of undesirable traits to improve productivity, improving nutritional content
Why would we produce siRNAs in plants to inhibit target genes in plant pathogens?
Virus-resistant and insect-resistant crops obtains using RNAi have been approved for cultivation
Dynamic adjustment of local chromatin packing by what two methods results in non-uniform packing of interphase chromosomes?
Chromatin remodeling complexes Histone modifications
In terms of packing, what happens to silence genes and genes being transcribed?
Silenced genes are condensed and compact Genes being transcribed are extended
Describe euchromatin
Loosely packed, transcriptionally active DNA
What is heterochromatin?
Compact regions containing no genes/transcriptionally quiescent genes
Where is heterochromatin found? Where is it most concentrated?
throughout the chromosome, but most concentrated near centromeres and telomeres
What happens to genes that are accidentally packaged into heterochromatin?
Those genes usually fail to express
How would someone disrupt specific structure genes?
Introducing deletion or insertion
What is another way of saying insertion? (shorthand)
Indel
How would one create up or down regulate gene expression?
By introducing indels in specific regulatory elements
How would one promote active expression of transgene for producing new products or engineering new metabolic pathways?
Introducing new genes (cassettes) to euchromatin loci
What is a gene gun?
Random insertion
What is the gene gun’s success rate for getting high expression transformants?
Low rate of success
Describe argo-bacterial mediated transformation
Assumed (more likely to target euchromatin area via natural selection) Not site specific
Transfection with viral vectors is used for disease causing genes (T/F)
True
What does DSB stand for?
DNA double strand break