Lab Isolation of Nucleic Acids 2

Question 1

Why should extracted nucleic acids be quantified

Answer 1

1. Ensures that extraction process was effective
2. Ensures standardisation in further analysis of DNA/RNA
3. Determines conc of nucleic acid relative to the conc of protein thats remaining in the extracted sample

Question 2

2 methods of quantitation of nucleic acids

Answer 2

1. electrophoresis
2. spectrophotometric analysis

Question 3

Gel electrophoresis: what is it

Answer 3

The movement of charged molecules in an electric field

Question 4

Gel electrophoresis: what do negatively charged molecules move towards

Answer 4

The positive electrode

Question 5

Gel electrophoresis: what do positively charged molecules move towards

Answer 5

The negative electrode

Question 6

Gel electrophoresis: what would high molecular weight genomic DNA appear like

Answer 6

Bright band with low mobility (near top of gel)

Question 7

At what absorbance do nucleic acids absorb light

Answer 7

• 260nm
• Absorbed through the adenine residues

Question 8

At what absorbance do proteins absorb light

Answer 8

At 280nm through the tryptophan residues

Question 9

One OD unit at 260nm for DNA

Answer 9

= 50mg/L DNA

Question 10

One OD unit at 260nm for RNA

Answer 10

= 40mg/L RNA

Question 11

What does it indicate if the absorbance at 260nm/280nm is less than 1.6

Answer 11

Contaminated with protein

Question 12

What does it mean if the absorbance at 260nm/28nm is greater than 2.0

Answer 12

Contaminated with RNA