Bio 111: lab exam 2 review TAMU Test
Questions All Solved Correctly.
What is the difference between the coding and non-coding region? - Answer Coding region:
comprised of genes that encode proteins (instructions that determine traits) and makes up 1-2%
of human DNA. • Noncoding region: makes up 98-99% of human DNA, contains STRs and is
responsible for regulatory functions such as gene transcription.
What are STRs? - Answer Short-tandem repeats (STRs) are unique repeating patterns of the
same nucleotide sequence. They can be used to differentiate one person from another.
What is a DNA profile? - Answer A DNA profile is a specific pattern of DNA attributes that is
obtained in the lab and can be used to identify an individual. • DNA profiling is the process of
determining an individual's DNA characteristics (profile) from a sample of bodily tissue
What does PCR stand for? What is the purpose of PCR? - Answer Polymerase Chain Reaction
• Purpose is to amplify DNA. In forensics, this can be used to obtain more DNA from a sample
that would otherwise be too small to analyze.
What is inside the master mix? - Answer 3 pairs of primers, loading dye, nucleotides (dNTPs),
Taq polymerase, mix buffer, and water. DNA sample is added to master mix.
What are the components of PCR and what do they do? - Answer • Template: the DNA from
the sample specimen serves as the template for replication • Primers: short stretches of DNA
that initiate the PCR reaction. • Required for annealing and Taq binding at specific sites • Base
sequences are complementary to the ends of the template DNA • Taq polymerase: adds dNTPs
to the template strand • Reads the original DNA sequence and creates a complimentary copy by
adding in the new DNA bases • Nucleotides (dNTPs): DNA bases (A, C, G, and T) serve as the
building blocks of DNA and are used to assemble new strands of DNA • Buffer: enables the
reaction to take place by ensuring the right conditions are met (controls pH)
What does the chelex do? - Answer The chelex resin chelates (absorbs) ions that inhibit
function of the Taq polymerase enzyme
What does the thermocycler do? - Answer Thermocyclers are instruments used to amplify
DNA and RNA samples by the polymerase chain reaction. The thermocycler raises and lowers
the temperature of the samples in a holding block in discrete, pre- programmed steps, allowing
for denaturation and reannealing of samples with various reagents.
What are the 3 steps of a PCR cycle? What happens during each step? - Answer • 1)
Denaturation, 2) Annealing, 3) Extension • Denaturation: When the double stranded template
DNA is heated to separate it into two single strands • Annealing: when the temperature is
, lowered to enable the DNA primers to attach to the template strands • Extension: when the
temperature is raised and the Taq polymerase enzyme synthesizes new DNA strands by adding
nucleotides to the template strands.
• What is the purpose of lysing the DNA? - Answer Lysis destroys the cell membrane and
releases the contents of the cell into the solution
What organism was Taq polymerase isolated from? - Answer Thermus aquaticus:
thermophilic bacterium (heat tolerant) that live in hot springs
What is multiplex PCR? - Answer Amplification of multiple targets into a single PCR
experiment by utilizing multiple primer pairs in a single reaction mixture
What is the purpose of gel electrophoresis? - Answer Allows you to separate a mixture of
different sized DNA molecules so that DNA samples can be compared to other known DNA
profiles.
What is the charge of DNA? - Answer DNA has a negative charge
What direction should DNA run? - Answer Toward the positively charged end (anode)
What are things that influence how far DNA will run? - Answer Charge of molecule: DNA
carries a negative charge so attracted to positive end • Size: Smaller molecules/fragments will
travel faster and further • Density of gel: the more dense the gel is, the slower the particles will
move. You want a gel that is dense enough to separate particles but that won't take too long
Who will run further from a well? 700bp of DNA or 200bp of DNA. - Answer 200 bp (smaller,
so travels faster and further)
Why is developing a DNA profile important? - Answer DNA testing allows forensic
investigators to identify a guilty individual with a high degree of certainty because the DNA
sequence of every person is unique (except for identical twins)
How did multiplex PCR help in our analysis versus just using a single pair of primers? - Answer
A single pair would not allow you to distinguish between samples/individuals with a high degree
of certainty
Why are DNA ladders (standards) important? - Answer They are used to determine the sizes
of bands in other DNA samples. Thus, we are able to compare them.
Questions All Solved Correctly.
What is the difference between the coding and non-coding region? - Answer Coding region:
comprised of genes that encode proteins (instructions that determine traits) and makes up 1-2%
of human DNA. • Noncoding region: makes up 98-99% of human DNA, contains STRs and is
responsible for regulatory functions such as gene transcription.
What are STRs? - Answer Short-tandem repeats (STRs) are unique repeating patterns of the
same nucleotide sequence. They can be used to differentiate one person from another.
What is a DNA profile? - Answer A DNA profile is a specific pattern of DNA attributes that is
obtained in the lab and can be used to identify an individual. • DNA profiling is the process of
determining an individual's DNA characteristics (profile) from a sample of bodily tissue
What does PCR stand for? What is the purpose of PCR? - Answer Polymerase Chain Reaction
• Purpose is to amplify DNA. In forensics, this can be used to obtain more DNA from a sample
that would otherwise be too small to analyze.
What is inside the master mix? - Answer 3 pairs of primers, loading dye, nucleotides (dNTPs),
Taq polymerase, mix buffer, and water. DNA sample is added to master mix.
What are the components of PCR and what do they do? - Answer • Template: the DNA from
the sample specimen serves as the template for replication • Primers: short stretches of DNA
that initiate the PCR reaction. • Required for annealing and Taq binding at specific sites • Base
sequences are complementary to the ends of the template DNA • Taq polymerase: adds dNTPs
to the template strand • Reads the original DNA sequence and creates a complimentary copy by
adding in the new DNA bases • Nucleotides (dNTPs): DNA bases (A, C, G, and T) serve as the
building blocks of DNA and are used to assemble new strands of DNA • Buffer: enables the
reaction to take place by ensuring the right conditions are met (controls pH)
What does the chelex do? - Answer The chelex resin chelates (absorbs) ions that inhibit
function of the Taq polymerase enzyme
What does the thermocycler do? - Answer Thermocyclers are instruments used to amplify
DNA and RNA samples by the polymerase chain reaction. The thermocycler raises and lowers
the temperature of the samples in a holding block in discrete, pre- programmed steps, allowing
for denaturation and reannealing of samples with various reagents.
What are the 3 steps of a PCR cycle? What happens during each step? - Answer • 1)
Denaturation, 2) Annealing, 3) Extension • Denaturation: When the double stranded template
DNA is heated to separate it into two single strands • Annealing: when the temperature is
, lowered to enable the DNA primers to attach to the template strands • Extension: when the
temperature is raised and the Taq polymerase enzyme synthesizes new DNA strands by adding
nucleotides to the template strands.
• What is the purpose of lysing the DNA? - Answer Lysis destroys the cell membrane and
releases the contents of the cell into the solution
What organism was Taq polymerase isolated from? - Answer Thermus aquaticus:
thermophilic bacterium (heat tolerant) that live in hot springs
What is multiplex PCR? - Answer Amplification of multiple targets into a single PCR
experiment by utilizing multiple primer pairs in a single reaction mixture
What is the purpose of gel electrophoresis? - Answer Allows you to separate a mixture of
different sized DNA molecules so that DNA samples can be compared to other known DNA
profiles.
What is the charge of DNA? - Answer DNA has a negative charge
What direction should DNA run? - Answer Toward the positively charged end (anode)
What are things that influence how far DNA will run? - Answer Charge of molecule: DNA
carries a negative charge so attracted to positive end • Size: Smaller molecules/fragments will
travel faster and further • Density of gel: the more dense the gel is, the slower the particles will
move. You want a gel that is dense enough to separate particles but that won't take too long
Who will run further from a well? 700bp of DNA or 200bp of DNA. - Answer 200 bp (smaller,
so travels faster and further)
Why is developing a DNA profile important? - Answer DNA testing allows forensic
investigators to identify a guilty individual with a high degree of certainty because the DNA
sequence of every person is unique (except for identical twins)
How did multiplex PCR help in our analysis versus just using a single pair of primers? - Answer
A single pair would not allow you to distinguish between samples/individuals with a high degree
of certainty
Why are DNA ladders (standards) important? - Answer They are used to determine the sizes
of bands in other DNA samples. Thus, we are able to compare them.
