Centrifugation Flashcards

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1
Q

Define the formula for relative centrifugal field (RCF).

A

1.12e-5 x (RPM)^2 * r

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2
Q

Name the five factors of sedimentation.

A
  1. Mass
  2. Density
  3. Shape
  4. Density of solvent
  5. Friction
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3
Q

In “18s rRNA”, what is “s”?

A

’s’ is the sedimentation coefficient.

s = 10^-13 seconds.

18s rRNA requires 18*10e-13 seconds to sediment.

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4
Q

Examplify what cellular components would be segregated when centrifuging lysate at low-, medium- and high speed.

A

low speed: Cellular debris (membranes, large organelles).

High speed: Mitochondria, lysosomes, peroxisomes.

Ultra-high speed: Viruses, macromolecules.

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5
Q

In the following formula, what is ‘k’?

t = k / s

A

t = time required for pelleting.
k = Clearing factor.
s = sedimentation constant.

The clearing factor differs from centrifuge to centrifuge.

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6
Q

What’s the concept behind rate-zonal centrifugation?

A

You place your sample in a tube containing a solvent with a known density gradient. When centrifuging, your sample will segregate to the density strata that corresponds to its own density.

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7
Q

How is rate-zonal centrifugation different from isopynic centrifugation?

A

In isopynic centrifugation, the density gradient of the solvent is produced during the centrifugation.

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8
Q

What is a nemogram?

A

It’s an analog diagram with which you can figure out relative centrifugal force (RCF), radius of centrifuge and/or speed (RPM), by knowing two of the factors.

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