Repetitive DNA Part 2 Flashcards Preview

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Flashcards in Repetitive DNA Part 2 Deck (16):
1

2 types of analytical ultracentrifugation

- equilibrium or bouyant density centrifugation
- sedimentation velocity centrifugation

2

two types of ultracentrifugation

- analytical
- preparative

3

analytical

- used to study the properties of molecules

4

preparative

- used to purify molecules by separating from other molecules so that their properties can be studied by other means

5

Equilibrium or bouyant density centrifugation

- high molecular weight DNA sheared and mixed with CsCl and a subjected to high g forces
- CsCl forms a gradient from highest density at the bottom to lowest density at the top
- DNA migrates to a position in the gradient where the density matches the density of the CsCl

6

what is formed in Equilibrium or bouyant density centrifugation

- a broad band is formed covering a range of fragments of different densities

7

Bouyant density is a function of

- G+C content
- not size

8

Higher G+C content

- higher density

9

if the satellite DNA has a GC content nearly the same as main GC content

- no satellite would be visible at all

10

sedimentation validity is a function of

- density
- size
- shape

11

how sedimentation velocity works

- put molecules on top of solution in centrifuge tube
- turn on centrifuge and measure rate of migration down the tube

12

large molecules sediment

- faster

13

what makes things sediment faster

- compact state

14

what makes things sediment slower

- extended state

15

How repetitive DNA can sometimes (but not always) be recognized as satellite DNA

- because of GC content that is different from the overall average GC content of DNA in the genome.

16

S values in complexes with subunits

- the S values of the subunits are not expected to add up to the S value of the entire complex.