Electrophoresis Exam – Questions & Answers (Rated
A+)
Electrophoresis Right Ans - is the separation of charged particles in a
colloidal dispersion under the influence of an electrical field
Zone electrophoresis Right Ans - is the migration of charged
macromolecules e.g. proteins in a porous supporting medium such as cellulose
paper, cellulose acetate, or agarose gel
Is electrophoresis a separation or measurement technique? Right Ans -
seperation
Amphoteric (Zwitterion) Right Ans - describes a cmpd that contains both a
proton-accepting R group and a proton-donating group and, therefore, can
take on a overall (-)ve change or an overall (+)ve charge depending on the
medium it is in
Buffer Right Ans - The electroyle sol'n that acts, firstly, as the pH
determining factor that sets the net electrical charge on the colloidal particles
and, secondly as the current-carrying medium in an electrophoresis cell
Buffer strength Right Ans - Refers to the ionic strength of an
electrophoresis buffer, which determines the resolving power of the system.
Weak buffers yield longer migration but more diffusion of the bands, whereas
stronger buffers tend to shorten migration, increase heat (leading to
denaturation) but yield better band resolution
Charge Right Ans - The net charge on a particle in solution. It is determined
by the pH of the supporting electrolyte ie. in protein electrophoresis the
charge is (-)ve b/c the pH of the buffer is 8.6
Constant current power supply Right Ans - A high voltage DC power that
provides a constant current over the period of an electrophoretic separation
and stabilizes heat generation and, thus, buffer evaporation
, Constant voltage power supply Right Ans - A high voltage DC power supply
that proves a constant voltage over the period of an electrophoretic
separation regardless of the change in cell current
Electroendoosmosis Right Ans - Describes the migration of uncharged or
weakly charged particles in an electrophoretic cell toward the cathode due to
the movement of protonated water molecules (H3O) in the buffer. Its effects
can be reduced or eliminated by the use of certain support mediums such as
purified agarose and polyacrylamide gel.
Electrophoretic mobility Right Ans - Describes the velocity at which a given
particle will migrate in an electrical field. It is directly related to the net charge
on the particle and indirectly related to the ionic radius (size) of the particle
and viscosity of medium
Isoelectric point Right Ans - the pH at which a substance has a zero net
charge
Migration Right Ans - The term used to describe the distance traveled by a
particle in an electrophoretic separation. A number of factors such as applied
voltage, time, buffer strength, and temperature affects migration
Resolution Right Ans - Refers to the ability of an electrophoresis system to
separate components of a sample into individual zones or bands
Rate of migration dependent on 5 factors: Right Ans - 1. net electrical
charge on the particle
2. size (MW) and shape (symmetry) of the molecule
3. electric field strength i.e. the voltage or current
4. properties of the support medium
5. temperature of the operation
Example of an ampholyte/zwitterion Right Ans - Proteins - can be (+)vely
or (-)vely charged
proteins at pH <pI Right Ans - net (+) charge due to the binding of protons
(ie. carboxy group accepts a proton COO- --> COOH) and migrate toward the
cathode (-ve terminal)
A+)
Electrophoresis Right Ans - is the separation of charged particles in a
colloidal dispersion under the influence of an electrical field
Zone electrophoresis Right Ans - is the migration of charged
macromolecules e.g. proteins in a porous supporting medium such as cellulose
paper, cellulose acetate, or agarose gel
Is electrophoresis a separation or measurement technique? Right Ans -
seperation
Amphoteric (Zwitterion) Right Ans - describes a cmpd that contains both a
proton-accepting R group and a proton-donating group and, therefore, can
take on a overall (-)ve change or an overall (+)ve charge depending on the
medium it is in
Buffer Right Ans - The electroyle sol'n that acts, firstly, as the pH
determining factor that sets the net electrical charge on the colloidal particles
and, secondly as the current-carrying medium in an electrophoresis cell
Buffer strength Right Ans - Refers to the ionic strength of an
electrophoresis buffer, which determines the resolving power of the system.
Weak buffers yield longer migration but more diffusion of the bands, whereas
stronger buffers tend to shorten migration, increase heat (leading to
denaturation) but yield better band resolution
Charge Right Ans - The net charge on a particle in solution. It is determined
by the pH of the supporting electrolyte ie. in protein electrophoresis the
charge is (-)ve b/c the pH of the buffer is 8.6
Constant current power supply Right Ans - A high voltage DC power that
provides a constant current over the period of an electrophoretic separation
and stabilizes heat generation and, thus, buffer evaporation
, Constant voltage power supply Right Ans - A high voltage DC power supply
that proves a constant voltage over the period of an electrophoretic
separation regardless of the change in cell current
Electroendoosmosis Right Ans - Describes the migration of uncharged or
weakly charged particles in an electrophoretic cell toward the cathode due to
the movement of protonated water molecules (H3O) in the buffer. Its effects
can be reduced or eliminated by the use of certain support mediums such as
purified agarose and polyacrylamide gel.
Electrophoretic mobility Right Ans - Describes the velocity at which a given
particle will migrate in an electrical field. It is directly related to the net charge
on the particle and indirectly related to the ionic radius (size) of the particle
and viscosity of medium
Isoelectric point Right Ans - the pH at which a substance has a zero net
charge
Migration Right Ans - The term used to describe the distance traveled by a
particle in an electrophoretic separation. A number of factors such as applied
voltage, time, buffer strength, and temperature affects migration
Resolution Right Ans - Refers to the ability of an electrophoresis system to
separate components of a sample into individual zones or bands
Rate of migration dependent on 5 factors: Right Ans - 1. net electrical
charge on the particle
2. size (MW) and shape (symmetry) of the molecule
3. electric field strength i.e. the voltage or current
4. properties of the support medium
5. temperature of the operation
Example of an ampholyte/zwitterion Right Ans - Proteins - can be (+)vely
or (-)vely charged
proteins at pH <pI Right Ans - net (+) charge due to the binding of protons
(ie. carboxy group accepts a proton COO- --> COOH) and migrate toward the
cathode (-ve terminal)
