problem 1 Solution Making/Problem Solving A chemotherapy drug for mice, Drug X,

Question

problem 1

Solution Making/Problem Solving

A chemotherapy drug for mice, Drug X, needs to be administered in a concentration of 7mg/kg for optimal effects to be observed. The mice in lab all weigh 45g.

How much of the drug (Mass X) will be injected into each of the mice?

Mass X has to be injected in a 200µL solution. If you want to make a 30mL stock solution of the drug, how much of the drug needs to be weighed?

problem 2

Assuming that you have two samples, A and B, one is DNA and the other is protein. Unfortunately, the labels are not clear. But you have the OD readings shown below:

Sample

OD 260

OD280

A

0.902

0.503

B

0.627

0.715

Which one is DNA and which one is protein?

Is this DNA pure or is it contaminated with proteins? How do you know?

problem 3

The picture below is the result of a SDS-PAGE. Lane 1 is a protein standard, which bands at (top to bottom) 70kDa, 60kDa, 50kDa, 40kDa, 30kDa, 20kDa. Lane 2, 3 and 4 represent Sample A, B and C.

According to the SDS gel presented above, which sample/lane contains Rubisco? Why/How do you know? (5 points)

Proteins/DNA have an overall ________________ charge. When proteins/DNA are placed on a gel, the wells with the protein/DNA are placed on the ___________________ (charge/side) of the electrophoresis chamber and with the application of current move toward the ____________________(charge/side) of the electrophoresis chamber. (5 points)

Sample

OD 260

OD280

A

0.902

0.503

B

0.627

0.715

Explanation / Answer

It is given,

7 mg / kg

So we convert it as

7000 micro gram / 1000 gram

= 7 micro gram / gram

Since the mouse weigh 45 gram

so per 45 gram we need "X " = 315 microgram

= 0.315 milligram

For second solution,

For 200 microlitre we require .315 mg

for 1000 microlitre ( 1 ml) we require = .315 *5

= 1.575 g

For 30 ml stock , we need to weigh = 1.575 * 30

= 47.25 g

Next,

DNA and Protein can be identified using the OD at 260 and 280. A good quality DNA would yield

A260 / A 280 ratio from 1.7 to 2 .

For sample A , A260/ A 280 is 1.7 which is a DNA

For Sample B, A260/ A280 is .8 which is a Protein.

Rubisco has a molecular mass of 560 kDa and consists of 8 small subunits each of 14 kDa and and 8 large subunit of 56 kDa. Since lane 2 has two bands around 56 and below 20. So it is this lane that contains rubisco.

Proteins/ DNA have an overall Negative charge. When proteins/DNA are placed on a gel, The wells with the protein/DNA are placed on the negetive (charge/side ) of the electrophoresis chamber and with the application of current move towards the positive charge /side of the electeophoresis chamber.

As the DNA sample have negetive charge because of the phosphate group present in the backbone, so on the application of current it moves towards the poaitive charge since electrons from from negative to positive. i.e from Anode to Cathode.

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