DNA Technology for ID and Forensics

Question 1

What do each of these abbreviations stand for and what is the “Genetics in Human Affairs” significance of each?
RFLP

Answer 1

Restriction Fragment Length Polymorphism

Location of probe relative to the variable cut site is important in determining fragment sizes that will be seen.

Question 2

What do each of these abbreviations stand for and what is the “Genetics in Human Affairs” significance of each?
PCR

Answer 2

Polymerase Chain Reaction

- Used in diagnosis of hereditary diseases, forensics, paternity testing, diagnosis of infectious diseases.

Question 3

What do each of these abbreviations stand for and what is the “Genetics in Human Affairs” significance of each?
STR

Answer 3

Short Tandem Repeats
The allele is based on the length of the DNA segment, with different alleles having different lengths because they have different numbers of copies of a short repeated DNA sequence.
Used for paternity and forensics, but must be polymorphic (many forms)

Question 4

What do each of these abbreviations stand for and what is the “Genetics in Human Affairs” significance of each?
SNP

Answer 4

Single Nucleotide Polymorphism
A specific site in the genome where DNA base varies in at least 1% of the population. There are about 10 million SNPs.
SNPs located near each other grouped as a haplotype: a sequence of SNP patterns along the length of a chromosome).
We can get about 500,000 haplotypes.
Used for testing genetic disorders, and ancestry (23andme)

Question 5

What is a SNP haplotype?

Answer 5

A sequence of SNP patterns along the length of a chromosome (closely linked).

Question 6

What are association studies (as related to Genetic Testing)?

Answer 6

Correlate presence/absence of specific SNP or SNP haplotype with presence/absence of genetic disorder.

Question 7

Be able to work problems like those in class involving paternity tests, inheritance patterns, who-dun-its, correlation of pedigree and test results.

Answer 7

(see practice problems)

Question 8

Describe the process of PCR. What are the 3 important steps?

Answer 8

1. Denature DNA by heating to 95 C. Allows strands to separate. Each strand serves as a template for replication.
2. Primers anneal: (50-65 C) to identify target that will be amplified.
3. Extending: Taq polymerase enzyme adds nucleotides to 3’ end of primer (72 C).
   Repeat…

Question 9

Who won a Nobel Prize for PCR?

Answer 9

Kary Mullis: developed PCR protocol

Question 10

What is a restriction enzyme and how is it important in RFLP analysis?

Answer 10

Enzyme that cuts DNA at a specific sequence.

Find an RFLP that varies with presence/absence of genetic disorder.

Question 11

Does DNA have a positive or negative charge?

Answer 11

Negative

Question 12

The process used to separate fragments of DNA on a gel is called ___________.

Answer 12

Electrophoresis

Question 13

Which pieces move faster in this process: large or small pieces of DNA?

Answer 13

Small

Question 14

What is a Probe? Why is it important in genetics testing?

Answer 14

Single stranded DNA that is tagged with a label allowing you to recognize where the probe (and any DNA that base-pairs to the probe) is located.

Question 15

What is a microarray (gene chip)? What can it be used for?

Answer 15

Used in SNP.
Probes are on chip.
Sample is incubated with chip and binds where SNPs match.
Computer will say which SNPs are present.

Question 16

Who are the 3 main companies for Direct to Consumer DNA testing?
o What is the source of DNA that is usually collected for these tests?

Answer 16

• 23andme.com
• deCodeme.com
• Ancestry.com
  SNPs

Question 17

What are some ethical issues surrounding the use of Direct to Consumer DNA tests? What are your opinions of these issues – where do you stand?

Answer 17

• No federal oversight
• How good are these SNPs at predicting disorder in various ethnic/cultural groups
• Do you warm relatives if medical test shows bad gene
• Right to “not know”?

Question 18

What major company recently received a grant to increase the size of their database and to conduct research involving their DNA database and medical conditions?

Answer 18

Kaiser Permanente

Question 19

Under what conditions can you be required to give a sample of your DNA for a DNA database?

Answer 19

• If you’re detained for a federal offense
• If you’re detained as an immigrant (illegal or not)
  No warrant needed (in some states) to collect from suspects.

Question 20

Genetic Testing is also used to help exonerate individuals who were wrongly convicted. Approximately how many have been exonerated to date using this information?

Answer 20

321 people

Question 21

What is meant by the terms partial match data and familial DNA testing?

Answer 21

Partial DNA matches are not searches themselves, but are the result of moderate stringency CODIS searches that produce a potential match that shares at least one allele at every locus. Partial matching does not involve the use of familial search software.
Familial DNA is the practice of creating new investigative leads in cases where DNA evidence found at the scene of a crime (forensic profile) strongly resembles that of an existing DNA profile (offender profile) in a state DNA database but there is not an exact match.