Agarose
Definition
Polysaccharide gel from seaweed. Large pore size, used for nucleic acids and large proteins. Standard for DNA submarine gels.
- Source
- Polysaccharide extracted from seaweed
- Pore size
- Large, compared to polyacrylamide
- Typical use
- Nucleic acids and large proteins
- Forensic application
- Standard matrix for DNA submarine (horizontal) gels
Common questions
Why is agarose chosen over polyacrylamide for DNA gels specifically?+
Its larger pore size resolves the much bigger fragment sizes typical of DNA restriction digests and PCR products, while polyacrylamide's finer pores suit smaller molecules like proteins where higher resolution at low molecular weight is needed.
What does 'submarine gel' mean in this context?+
It refers to horizontal gel electrophoresis where the agarose slab is fully submerged in a buffer tank, as opposed to a vertical slab gel clamped between plates, which is the usual format for polyacrylamide protein separations.
Related terms
- Capillary Electrophoresis (CE)
- A separation technique that resolves DNA fragments by size through a polymer-filled glass capillary under an applied electric field. Single-base resolution is...
- Electrophoretic Mobility (μ)
- Velocity of a charged particle per unit electric field, μ = v/E. Depends on charge, size, shape and the viscosity of the...
- IEF (Isoelectric Focusing)
- Electrophoresis across an immobilised pH gradient. Each protein migrates until it reaches its pI and stops. Very high resolution; used in haemoglobin...
- Immunoelectrophoresis
- A two-step technique: proteins are first separated by electrophoresis in agar gel, then antiserum diffuses from a parallel trough and forms precipitin...
- Isoelectric Point (pI)
- pH at which a molecule (usually a protein) carries zero net charge and stops migrating. The basis of isoelectric focusing (IEF).
- Polyacrylamide (PAGE)
- Cross-linked synthetic gel with tunable, smaller pore size. Used for proteins and small DNA fragments.
- Precipitin Arc
- Curved line of antigen-antibody precipitate that forms at equivalence in immunoelectrophoresis. Shape and position identify the antigen.
- SDS-PAGE
- PAGE run with sodium dodecyl sulphate. SDS coats proteins with uniform negative charge, so separation is by molecular weight alone.