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Sergeeva-Olga [200]
3 years ago
7

Which best describes why the cell membrane is selectively permeable?

Biology
1 answer:
alukav5142 [94]3 years ago
6 0

Answer:

The answer is It allows only certain materials to enter and exit the cell.

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6. (3 pts) After transformation, 40 colonies were present on the plate. What is the transformation efficiency of the competent c
natali 33 [55]

Answer:

Given:

Number of colonies on plate = 40

Amount of DNA used for transformation = 100ng

Volume of competent cells used = 100ul

Total volume = 1ml (1000ul)

Volume plated for growth = 200ul

The amount of cells transformed per 1 µg of DNA is called the transformation efficiency

(CFU is colony forming units) => (number of colonies on plate/ng of DNA plated) X 1000 ng/µg = CFU/µg of DNA

Amount of DNA used for plating = 100ng * (200/1000)

                                                      = 100ng * (1/5)

                                                      = 100/5 = 20ng

Efficiency calculation = 40 colonies / 20ng = 2 colonies/ng

               (2 colonies/ng) * (1000 ng/µg) = 2000 CFU/ug DNA

Transformation efficiency = 2000 Transformants / ug DNA

                                          = 2 x 10³ Transformants / ug DNA

Explanation:

Efficiency of transformation is highest in the 100 pg-1 ng range, so Low transformation efficiency could be because of high amount of DNA used for transformation.

6 0
2 years ago
Select the answer that shows all the words that should be capitalized in the sentence.
ivann1987 [24]
D, Pennsylvania, Gettysburg, Address
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Place it Correct spot that’s all tbh
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Answer:

All planets have a circular orbit with the sun at the center

3 0
2 years ago
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What common North Carolina geological feature is pictured in the graphic below?
8_murik_8 [283]

Answer:

the awnser is A river basin

Explanation:

because I'm smart just trust me m8

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Plants that produce seeds within a cone are called _____.
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