Question

question 11 (2 points)
what reagent did we use to precipitate the dna?
○ suave
○ salt solution
○ distilled water
○ ethyl alcohol
question 12 (2 points)
the length of an e. coli cell is 2 um. what is the length in cm?
○.0002
○.002
○ 200
○ 2000

Explanation:

Question 11

In DNA precipitation, ethyl alcohol (like ethanol) is commonly used as DNA is insoluble in alcohol, causing it to precipitate out. Suave is a cosmetic product, salt solution is used in lysis or other steps, and distilled water doesn't precipitate DNA.

Step1: Recall unit conversions

We know that \( 1\ \mu\text{m} = 10^{-4}\ \text{cm} \) (since \( 1\ \mu\text{m}=10^{-6}\ \text{m} \) and \( 1\ \text{m} = 100\ \text{cm} \), so \( 1\ \mu\text{m}=10^{-6}\times100 = 10^{-4}\ \text{cm} \)).

Step2: Convert 2 μm to cm

Multiply the length in μm by the conversion factor: \( 2\ \mu\text{m} \times 10^{-4}\ \frac{\text{cm}}{\mu\text{m}} = 2\times10^{-4}\ \text{cm}=0.0002\ \text{cm} \).

Answer:

ethyl alcohol

Question 12