Untitled Deck

Question 1

Why is studying DNA essential for understanding and treating human diseases?

Answer 1

Studying DNA allows researchers to identify genetic factors underlying diseases, enabling targeted treatments and personalized medicine.

Question 2

How does the purity and quantity of extracted DNA affect clinical research?

Answer 2

Purity and quantity of DNA are crucial for accurate downstream applications like PCR, as contaminants can inhibit reactions and compromise results.

Question 3

List four different types of samples from which human DNA can be isolated.

Answer 3

Blood, buccal cells, hair follicles, and tissue biopsies.

Question 4

Why are buccal cells considered a convenient source for DNA extraction?

Answer 4

Buccal cells are non-invasive to collect and provide sufficient DNA for analysis.

Question 5

How does PBS preserve cells during DNA extraction?

Answer 5

PBS prevents cell degradation by maintaining an isotonic environment.

Question 6

Name the three common methods of DNA extraction.

Answer 6

Phenol-chloroform, silica-based, and magnetic bead methods.

Question 7

What are the advantages of silica-based extraction over other methods?

Answer 7

Silica-based methods are faster, avoid toxic chemicals, and yield high-quality DNA.

Question 8

Why is it important to ensure no food or drink is consumed 30 minutes before buccal swab collection?

Answer 8

To prevent contamination of the DNA sample with food particles or foreign DNA.

Question 9

What is the purpose of adding proteinase K and lysis buffer during the lysis step?

Answer 9

Proteinase K breaks down proteins, while lysis buffer disrupts cell membranes and denatures proteins, releasing DNA.

Question 10

How does ethanol enhance DNA binding to the silica membrane?

Answer 10

Ethanol removes water, creating conditions that favor DNA binding to silica.

Question 11

Why is it important to incubate the sample at 56°C during lysis?

Answer 11

Incubation at 56°C activates proteinase K and ensures efficient cell lysis.

Question 12

During the washing step, why are two different buffers used?

Answer 12

To sequentially remove proteins, salts, and other impurities.

Question 13

What is the role of the elution buffer in the final step of DNA extraction?

Answer 13

The elution buffer releases bound DNA from the silica membrane for collection.

Question 14

What is the role of proteinase K in DNA extraction?

Answer 14

Proteinase K digests proteins, including histones, freeing DNA from protein complexes.

Question 15

How do chaotropic salts in the lysis buffer aid in DNA isolation?

Answer 15

Chaotropic salts disrupt hydrogen bonds and solubilize cellular components, aiding DNA release.

Question 16

Why is absolute ethanol necessary during the DNA binding step?

Answer 16

Absolute ethanol promotes DNA precipitation and binding to the silica membrane.

Question 17

What does the pre-wash solution remove from the sample?

Answer 17

The pre-wash solution removes residual salts and contaminants.

Question 18

What is the purpose of the wash solution?

Answer 18

To clean the DNA-bound silica by removing remaining impurities.

Question 19

How does the elution buffer facilitate DNA retrieval from the silica membrane?

Answer 19

The elution buffer rehydrates the DNA, releasing it from the silica surface.

Question 20

Why is it important to determine the concentration and purity of extracted DNA before using it in experiments?

Answer 20

Ensuring proper concentration and purity prevents reaction failures and ensures reliable experimental results.

Question 21

How does the A260/A280 ratio indicate DNA purity?

Answer 21

The A260/A280 ratio measures protein contamination, with pure DNA having a ratio of ~1.8.

Question 22

What are the acceptable values for the A260/A280 ratio, and what do they signify?

Answer 22

Ratios of 1.8–2.0 indicate pure DNA, while lower values suggest protein contamination.

Question 23

Why is it necessary to blank the spectrophotometer with a blanking solution before measuring DNA concentration?

Answer 23

To account for background absorbance and ensure accurate readings.

Question 24

What does an A260/A280 ratio below 1.7 indicate about your DNA sample?

Answer 24

The sample is contaminated with proteins.

Question 25

What steps should be taken to clean the Nano-Drop before and after measuring DNA concentration?

Answer 25

Clean the Nano-Drop pedestal with distilled water and lint-free wipes before and after measurements.

Question 26

How much DNA is typically extracted from one buccal swab?

Answer 26

Approximately 2–5 μg of DNA is typically extracted.