L1: Introduction to gene tech Flashcards
What is a transgene?
A gene that has been artificially introduced into a genome
RITs (random integration transgenics)
Process of introducing foreign DNA into a plant or animal cell randomly. Genetic material is inserted into the host genome in an uncontrolled manner, resulting in unpredictable expression manners and potentially disrupting cellular functions.
Random vs. target transgenics
Random: expression of transgene is randomly allocated
Target: expression of transgene is allocated to a specific area
What does it mean that expression “oscillates”?
Oscillating gene: A gene that is expressed in a rhythmic pattern or in periodic cycles. Oscillating genes are often circadian which means that circadian rhythms controlled by oscillating genes have a period of 24 hours.
Why do position and orientation in a gene matter?
Matters as they can influence gene expression. If a gene is located in a certain part of the genome, it may be more or less accessible to the cellular machinery responsible for gene expression. If the gene is oriented in a certain way, it may be more or less accessible to regulatory elements such as enhancers or repressors which control gene expression. Therefore, the position and orientation of genes can have a significant impact on the level of expression and on the phenotype of an organism.
How does position affect PcP1 promoter?
Position effects can influence the activity of the promoter leading to changes in the levels of gene expression.
Constitutive promoter (drives gene expression) regardless of the cell type or growth conditions. The activity of the PcP1 promoter can be influenced by its position within the genome as well as surrounding chromatin structure and epigenetic mods.
If PcP1 is positioned near a region of heterochromatin (tightly packed + inaccessible to cellular machinery) activity of the promoter may be reduced.
How is DNA structured?
DNA strand, nucleotide base pairs that help to form a double helix structure. DNA is also antiparallel (5’-3’).
DNA strand is wrapped around histones (proteins) forming a nucleosome.
A nucleosome is tightly packed, forming a chromosome structure where genetic information is tightly packed (coiled).
How is the mammalian genome organized?
It is organized into domains. Higher-order nuclear compartments harbor DNA sequences with a specific replication timing.
TAD (topologically associated domains) are fundamental units of 3D nuclear organization.
How is transcription activated?
Promoters and enhancers are often bound by organism-specific and cell-type-specific proteins, which work together to drive the expression of a gene.
What are promoters?
Sequences of DNA that located near the start of a gene and provide the binding site for the RNA polymerase enzyme, which initiates transcription. Promoters also contain cis-acting elements (TATA boxes and CAAT boxes) that help recruit other factors required for transcription initiation.
What are enhancers?
Non-coding DNA sequences located far away from promoters also regulate gene expression by increasing the rate of transcription. They bind to specific transcription factors that help control gene expression. Bound transcription factors can interact with the promoter and recruit other factors required for transcription initiation.
What are transcription factors?
Play an essential role in controlling normal biological processes and are frequently implicated in disease. Different transcription factors can turn on at different times during successive generations of cells. In subsequent generations, it is the combination of different transcription factors that can determine cell type.
What is gene modulation?
Altering the expression of a gene at one of various stages. Modulation can be achieved using different biotechnologies such as RNAi(interference), non-precision drugs, and artificial transcription factors.
When the repressor is inactive, then transcription is on. When the repressor is active (binding to some substance) then transcription is off.
What are insulated neighborhoods?
Chromosomal loop structures formed by the physical interaction of two DNA loci, bound by the transcription factor CTCF and co-occupied by cohesin.
