Molecular Biology Answers

1. Mang Nestor has a poultry farm. Every morning, he collects eggs and sell it in the market. Those are unsold, he made it as salted egg. In doing this, the eggs were soaked in a container having one liter of water with 1 kg dissolved salt solution. After 18 days, Mang Nestor collected salted eggs for his everyday consumption. What transport mechanism/concepts can be applied in salted egg making? Explain

describe the milestone in quantitative genome,how sequencing approaches got evolved in ge netic paradigm

discussed the Laws of Thermodynamics and their relation to energy and energy transfer. Energy transfers take place constantly in everyday activities. Think of two scenarios: cooking on a stove and driving. Explain how the second law of thermodynamics applies to these two scenarios.

Can you give one example, from the literature what happens if you don't establish protein purity?

Question 5: As previously stated, the concentration of NaCl, KCl and Phosphate in working strength 1 x PBS is 0.137M NaCl, 0.012M Phosphate, 0.0027M KCl, pH 7.4 How do they compare to the concentrations you calculated for 10x PBS?

Question 4: Using periodic table found in your textbook, calculate (to 2 decimal places) the molecular mass for each of the compounds used to make PBS.



Create the following table and fill it in with the mass of each component required to make 1 liter of 10 x PBS (the recipe for 10x PBS is below question 2) and their final molar concentration in the buffer calculated as described above.



Compound formula Molecular mass (in g/mol) Mass of compound per liter of 10x PBS (in g) Molar concentration (in mol/l)

NaCl

KCl

Na2HPO4

KH2PO4

Question 2: Based on the equation below, which ion plays the role of hydrogen-ion donor (acid) and which ion plays the role of hydrogen-ion acceptor (base) in PBS?

H2PO4-(aq) ⇆ H+(aq) + HPO42-(


The composition of PBS is 0.137M NaCl, 0.012M Phosphate, 0.0027M KCl, pH 7.4. Below is the protocol to make 1 liter of 10x concentrate PBS.

Combine the following:

• 80g NaCl

• 2g KCl

• 14.4g Na2HPO4 (dibasic anhydrous)

• 2.4g KH2PO4 (monobasic anhydrous)

• 800mL distilled H2O



1. Adjust pH to 7.4 with HCl

2. Add H2O to 1L

3. Autoclave for 20 minutes on liquid cycle. Store at room temperature.

Question 13: Taking into account your response to question 5, now that you have made a 10x PBS solution, describe how you would prepare 1 liter of 1x working solution PBS, including which glassware you would use. Will you need to adjust the pH again?

Question 12: The last step in the protocol is to autoclave the 10x PBS solution. Why do you think this step is important? Look up the definition of autoclave if you are unsure what it means.

Question 11: The PBS protocol above says to adjust pH to 7.4 with HCl. What does this imply on the pH of 10x PBS before adjusting the pH, would it be greater or smaller than 7.4?