Podcast
Questions and Answers
During which phase of the Polymerase Chain Reaction (PCR) process are hydrogen bonds broken between DNA strands?
During which phase of the Polymerase Chain Reaction (PCR) process are hydrogen bonds broken between DNA strands?
- Denaturing phase (correct)
- Extension phase
- Annealing phase
- Replication phase
What is the purpose of primers in the Polymerase Chain Reaction (PCR)?
What is the purpose of primers in the Polymerase Chain Reaction (PCR)?
- To prevent the Taq polymerase from denaturing.
- To digest the DNA into smaller fragments.
- To separate the DNA strands during the denaturing phase.
- To provide a starting point for DNA replication by Taq polymerase. (correct)
Why is Taq polymerase used in PCR instead of other DNA polymerases?
Why is Taq polymerase used in PCR instead of other DNA polymerases?
- Taq polymerase is heat-stable and can withstand the high temperatures of PCR. (correct)
- Taq polymerase is less expensive than other DNA polymerases.
- Taq polymerase does not require primers.
- Taq polymerase is more efficient at replicating DNA than other polymerases.
In gel electrophoresis, what property of DNA allows it to be separated?
In gel electrophoresis, what property of DNA allows it to be separated?
Why does DNA move towards the positive electrode in gel electrophoresis?
Why does DNA move towards the positive electrode in gel electrophoresis?
What is the role of restriction endonucleases in preparing DNA for gel electrophoresis?
What is the role of restriction endonucleases in preparing DNA for gel electrophoresis?
Which of the following is NOT a typical application of PCR and gel electrophoresis?
Which of the following is NOT a typical application of PCR and gel electrophoresis?
How do smaller DNA fragments travel compared to larger fragments during gel electrophoresis?
How do smaller DNA fragments travel compared to larger fragments during gel electrophoresis?
Which scenario would require the use of both PCR and gel electrophoresis?
Which scenario would require the use of both PCR and gel electrophoresis?
Why is it essential to use the same restriction enzyme when comparing DNA fragments from different sources?
Why is it essential to use the same restriction enzyme when comparing DNA fragments from different sources?
Flashcards
What is PCR?
What is PCR?
Amplifies a small DNA fragment to make more copies for analysis.
What is Gel Electrophoresis?
What is Gel Electrophoresis?
A technique that separates DNA fragments based on size using an electrical field.
What is the Denaturing Phase?
What is the Denaturing Phase?
Phase of PCR where DNA is heated to 98°C to break hydrogen bonds and separate strands.
What is the Annealing Phase?
What is the Annealing Phase?
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What is the Extension Phase?
What is the Extension Phase?
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What are Restriction Enzymes?
What are Restriction Enzymes?
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What is Taq Polymerase?
What is Taq Polymerase?
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What are Primers in PCR?
What are Primers in PCR?
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What is DNA Profiling Used For?
What is DNA Profiling Used For?
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What is Polymerase Chain Reaction (PCR)?
What is Polymerase Chain Reaction (PCR)?
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Study Notes
- Revision notes covering PCR, gel electrophoresis, and their applications.
PCR - Amplifying DNA
- PCR is used to amplify small DNA fragments.
- It helps in studying genes more closely and identifying individuals in crime investigations.
- The reaction occurs in a chamber with free nucleotides, primers enabling replication, and Taq polymerase which is a heat-stable DNA polymerase from hot springs that does not denature.
PCR Process
- First, identify the region of interest.
- Denaturing phase: Heat to 98°C to break hydrogen bonds, separating the strands.
- Annealing phase: Reduce the temperature to 60°C, enabling complementary pairing of primers to the DNA template.
- Extension phase: Occurs at 72°C; primers bond, allowing Taq polymerase to replicate using primers as a starting point.
- After replicating the DNA, the strands are heated to separate, and the cycle repeats.
- Each cycle doubles the DNA, providing numerous copies for gel electrophoresis.
Gel Electrophoresis
- Gel electrophoresis helps to identify key DNA elements.
- DNA moves through a gel using electrical currents and separates based on size and distance from the starting point.
- DNA, having a negative charge, moves towards the positive electrode in an electrical field.
- Restriction endonuclease enzymes digest DNA to get appropriately sized fragments by cutting the backbone and create shorter fragments.
- This is used for DNA fingerprints and profiles, with the exception of identical twins, everyone will be different.
- Samples are placed in small wells at the end of a polymer, submerged in a buffer solution at the negative end, and then the electrical current is run.
- Small pieces travel faster through the spaces in the gel.
Uses of Processes
- DNA profiling is used for paternity testing and forensic investigations.
- It is possible to create specific profiles for individuals.
- DNA can be found due to continuous shedding of cells.
- It helps study biodiversity and common ancestors.
- It aids in understanding which bacteria strands are responsible for illnesses.
Restriction Enzymes
- Restriction enzymes cut DNA sequences when specific base combinations are present, resulting in different length sequences.
- Length of DNA fragments must match to match DNA.
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