Extraction

Question 1

(True or False) Inhibitors fall into three basic types which arise from body fluids(internal), substrates, or the extraction process.

Answer 1

True

Question 2

What is the purpose of a differential DNA extraction?

Answer 2

To separate sperm cells from all other cells

Question 3

(True or False) A pH shift from lower to higher during silica-based DNA purification assists in the elution of DNA.

Answer 3

True

Question 4

What extraction method creates the disruption of water molecules by introducing chaotropic salts in order to bind DNA to silica?

Answer 4

Solid Phase

Question 5

(True or False) Spematozoa are selectively lysed prior to lysing non-sperm cells because they are easier to break open.

Answer 5

False; Non-sperm cells are selectively lysed prior to spermatozoa because they are easier to break open/Spermatozoa are harder to break open

Question 6

What amount of DNA is contained within a human diploid cell?

Answer 6

6 picograms

Question 7

What may be added to a bead-based purification to increase the DNA yield for low concentration samples?

Answer 7

Carrier RNA (cRNA)

Question 8

Why is dithiothreitol added when extracting DNA from hair and sperm cells?

Answer 8

To reduce disulfide bonds

Question 9

What are the steps during solid phase extraction and what occurs during each step?

Answer 9

1. Lyse
2. Bind
3. Wash
4. Elute

Question 10

What are the 3 main types of inhibitors?

Answer 10

1. Internal inhibitors
2. Substrate inhibitors
3. Inhibitors from the extraction process

Question 11

List 3 internal inhibitors.

Answer 11

1. Heme, immunoglobulin G, hemin, bilirubin, and bile salts (Blood)
2. Bacteria (Vaginal, buccal, and fecal samples)
3. Melanin (Hair and tissue)
4. Calcium (bone and teeth)
5. Polyamines, spermine, and spermidine (sperm)
6. Urea (Urine)

Question 12

List 3 substrate inhibitors.

Answer 12

1. Textile dyes - Indigo dyes used in denim
2. Fabric - Tannic acid used to tan leather and resins used in “wrinkle resistant” fabrics
3. Environmental samples - Humic acid found in soil and heavy metals
4. Food compounds - organic compounds, phenolic compounds, glycogen, fats, and calcium in milk

Question 13

List 3 inhibitors from the extraction process.

Answer 13

1. Salts
2. Guanidine
3. Proteases such as PK
4. Magnetic beads
5. Detergents

Question 14

What are the goals of DNA extraction?

Answer 14

To isolate and purify DNA by removing inhibitors and nucleases and separating the DNA from other cellular components.