Repetitive DNA Part 2 Flashcards
1
Q
2 types of analytical ultracentrifugation
A
- equilibrium or bouyant density centrifugation
- sedimentation velocity centrifugation
2
Q
two types of ultracentrifugation
A
- analytical
- preparative
3
Q
analytical
A
- used to study the properties of molecules
4
Q
preparative
A
- used to purify molecules by separating from other molecules so that their properties can be studied by other means
5
Q
Equilibrium or bouyant density centrifugation
A
- 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
Q
what is formed in Equilibrium or bouyant density centrifugation
A
- a broad band is formed covering a range of fragments of different densities
7
Q
Bouyant density is a function of
A
- G+C content
- not size
8
Q
Higher G+C content
A
- higher density
9
Q
if the satellite DNA has a GC content nearly the same as main GC content
A
- no satellite would be visible at all
10
Q
sedimentation validity is a function of
A
- density
- size
- shape
11
Q
how sedimentation velocity works
A
- put molecules on top of solution in centrifuge tube
- turn on centrifuge and measure rate of migration down the tube
12
Q
large molecules sediment
A
- faster
13
Q
what makes things sediment faster
A
- compact state
14
Q
what makes things sediment slower
A
- extended state
15
Q
How repetitive DNA can sometimes (but not always) be recognized as satellite DNA
A
- because of GC content that is different from the overall average GC content of DNA in the genome.
16
Q
S values in complexes with subunits
A
- the S values of the subunits are not expected to add up to the S value of the entire complex.
