FIS 201 – DNA Mechanics Study Guide
Why is it important for forensics that in double stranded DNA, we always see the specific pairs
A-T and G-C stuck together? - ANS✔✔ If we have one half of the double helix, we can
reconstruct the other perfectly
Let's take a look at Janet Weiss' 15th pair of chromosomes:
-Chromosome 15A:
At locus 1352, Janet has the sequence ATCGGG
At locus 1785, Janet has the sequence ATCGGG
-Chromosome 15B:
At locus 1352, Janet has the sequence ATCGGG
At locus 1785, Janet has the sequence ATCGGA
Which statement describes her situation correctly? - ANS✔✔ At locus 1352, she is homozygous
At locus 1785, she is heterozygous
There are a maximum of two alleles that can be found at any given locus. (For example, blue
eyes or brown eyes) - ANS✔✔ False
The most common DNA reference sample is a [blank] swab. - ANS✔✔ [buccal]
During the investigation of a homicide, Army CID investigators find the following bed sheet.
Place the steps to correctly collect and preserve the stains for DNA analysis. - ANS✔✔ 1. Allow
the blood stains to air dry
2. Cut a small sample from the bedding, wearing gloves and using sterilized tools
3. Store the samples in a -40° to -80° freezer until ready to process
4. Lyse the cells open to release the DNA
Why is it important for forensics that in double stranded DNA, we always see the specific pairs
A-T and G-C stuck together? - ANS✔✔ If we have one half of the double helix, we can
reconstruct the other perfectly
Let's take a look at Janet Weiss' 15th pair of chromosomes:
-Chromosome 15A:
At locus 1352, Janet has the sequence ATCGGG
At locus 1785, Janet has the sequence ATCGGG
-Chromosome 15B:
At locus 1352, Janet has the sequence ATCGGG
At locus 1785, Janet has the sequence ATCGGA
Which statement describes her situation correctly? - ANS✔✔ At locus 1352, she is homozygous
At locus 1785, she is heterozygous
There are a maximum of two alleles that can be found at any given locus. (For example, blue
eyes or brown eyes) - ANS✔✔ False
The most common DNA reference sample is a [blank] swab. - ANS✔✔ [buccal]
During the investigation of a homicide, Army CID investigators find the following bed sheet.
Place the steps to correctly collect and preserve the stains for DNA analysis. - ANS✔✔ 1. Allow
the blood stains to air dry
2. Cut a small sample from the bedding, wearing gloves and using sterilized tools
3. Store the samples in a -40° to -80° freezer until ready to process
4. Lyse the cells open to release the DNA
