lab 1

Question 1

centrifugation is a _________
on the basis of ______
It is based on

Answer 1

basic biochemical technique that can be used to separate cells, organelles, membranes, macromolecules ………

• mass shape and density
• the outward movement of an object as the result of centrifugal force, angular momentum

Question 2

ultracentrifugation

Answer 2

term for rotor speeds taht exceed 20 000 rpm

Question 3

seperation in centrifugation is only proportional to mass if

Two factors that are affected by these parameters are

Answer 3

the objects have the same size and density
- the rate of diffusion back against the centrifugal force, and the friction caused by forcing the object through the liquid

Question 4

Both diffusion and friction are influenced by the

And the ____________ will be affected by these parameters

Answer 4

viscosity and density of the liquid

rate of sedimentation

Question 5

Soluble proteins usually fold to form

And have a shape describe by ______

Answer 5

compact ellipsoids

the two radii, alpha beta, or the stokes radius(average)

Question 6

In general soluble proteins can be separated as a function of their mass because

Answer 6

they have the same shape and same density

Question 7

The significance of rod shaped proteins

Answer 7

The would not have different properties than an ellipsoid protein, so it’s molecular mass can not be determined by comparison with standards(globular)

Question 8

Factors that influence separation with organelles and membrane preparations

Answer 8

speed of centrifugation
density of separating medium
density gradients
viscosity
pH
ionic strength

Question 9

Ultracentrifuges operate at speeds in excess of
The rotor is spun in an
At high speeds the chamber is

Answer 9

80 000 rpm
air evacuated, cooled chamber to keep temperature low
evacuated to prevent the rotor from heating due to the frictional collision with air molecules

Question 10

g is a function of

if one has access to ____________ then g can be calculated, otherwise

Answer 10

distance from the center of rotation
exactly the same rotor, or a description of the rotor dimensions
It is impossible

Question 11

smooth migration of a particle disturbed by
these disturbances can be alleviated by
because these substances _______ but affect _______

Answer 11

mechanical vibration, thermal gradients, convection
forming a gradient of a supportive material(sucrose, glycerol, CsCl)
increase viscosity and dampen effects of distribution
affect the speed at which a particle moves under centrifugal force

Question 12

In sedimentation equilibrium centrifugation

So the separation is based upon the

Answer 12

sedimenting particle moves through the gradient until it reaches a point where their densities and that of the medium are equal
Buoyant density of the particle and is independent of the shape and size of the particle

Question 13

RCF =

Answer 13

1.1119 x 10^-5 (rpm^2)r

Question 14

For large structure with high molecular weights, it is impractical to measure them as ________
But it is possible to __________

Answer 14

real units of mass

describe their size as a function of their sedimentation properties

Question 15

marker for mitochondria

Answer 15

succinate dehydrogenase

Question 16

marker for cytosol

Answer 16

lactate dehydrogenase

Question 17

maker for microsomes

Answer 17

glucose-6-phosphote

Question 18

microsomes

Answer 18

sealed vesicles that form spontaneously when the endoplasmic reticulem is disrupted

Question 19

Percoll is ____
it consists of
which is rendered non toxic to cells by coating it with

Answer 19

a medium for density gradient centrifugation
collloidal silica,
polyvinylpyrrolidone