MicroRNAs as an Experimental Tool: RNAi

MicroRNAs regulate gene expression by knocking down the expression of specific genes.  This knockdown can occur either by targeting an mRNA for degradation or by blocking its translation or both.  Somewhat independently of the identification of microRNAs as a natural cellular process, a laboratory technique called RNA interference (RNAi) was developed that relies on the […]

CRISPR applications: In vivo DNA editing and more

The CRISPR/Cas system that evolved to protect bacteria and archaea from foreign DNA has rapidly been used by molecular biologists for a number of purposes.  Recombination in the cell initiates with a double-stranded break in the DNA sequence.  Once that break has been made (and not repaired), the sequences at that site can be altered, […]

Making DNA Visible: DNA Stains and Labels

What does the chemical DNA look like, and how does one see it?  DNA can be precipitated out of solution using alcohol and salt.  The precipitate, which can be spooled out like long pasta, is clear if it is unbroken.  DNA is colorless.  Thus, when DNA molecules are separated by electrophoresis or hybridized with one […]

The Importance of the DNA Backbone: separating DNA molecules by size

The DNA molecule has a long backbone of phosphate molecules on each strand; the backbone can be compared to the uprights on a ladder.  A number of different important laboratory techniques have been developed based on the physicochemical properties of the phosphate backbone; even more techniques are designed around the base pairs, which we discuss […]