Biotechnology: Genetic Engineering Techniques (College Board AP® Biology): Flashcards
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- FrontGel Electrophoresis
Define gel electrophoresis.
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Define gel electrophoresis.
Gel electrophoresis is a process that separates DNA fragments (or other molecules) by their size and charge.
Which two properties of molecules does gel electrophoresis use to separate them?
Their size and their electrical charge.
Which types of molecules can be separated using gel electrophoresis?
DNA, RNA, and proteins.
DNA is negatively charged, so DNA molecules move toward the electrode.
DNA is negatively charged, so DNA molecules move toward the positive electrode.
True or False?
During gel electrophoresis, smaller molecules move through the gel more slowly than larger molecules.
False.
Smaller molecules move through the gel more quickly, while larger molecules move more slowly.
Why do smaller molecules move through the gel more quickly than larger ones?
The tiny pores in the gel let smaller molecules pass through more easily, so they travel faster; larger molecules are held back and move more slowly.
In the gel, smaller molecules move more than larger molecules.
In the gel, smaller molecules move more quickly than larger molecules.
How can the size of a DNA fragment of unknown length be determined using gel electrophoresis?
By comparing the distance travelled by the unknown fragment with the distances travelled by fragments of known size.
Define DNA profile.
DNA profile is a pattern of DNA fragments produced by gel electrophoresis that can be used to compare DNA from different samples.
Give two useful applications of the DNA profiles produced by gel electrophoresis.
Determining how closely related individuals or species are
Forensic analysis, e.g. identifying DNA found at a crime scene
True or False?
Gel electrophoresis can aid in the process of DNA sequencing.
True.
The DNA profiles produced by gel electrophoresis can be used to help with DNA sequencing, as well as forensic analysis and comparing relatedness.
analysis uses gel electrophoresis to identify DNA found at a crime scene.
Forensic analysis uses gel electrophoresis to identify DNA found at a crime scene.
Define polymerase chain reaction (PCR).
Polymerase chain reaction (PCR) is a technique used to amplify a DNA fragment, producing many identical copies from a small initial sample.
Define amplification.
Amplification is the production of many identical copies of a DNA fragment from a small starting sample of DNA.
What are the three key stages of each PCR cycle?
Denaturation
Annealing
Extension (elongation)
What happens during the denaturation stage of PCR?
The double-stranded DNA is heated to break the hydrogen bonds holding the two strands together, separating it into single strands.
What happens during the annealing stage of PCR?
The temperature is decreased so that DNA primers can anneal to the ends of the single strands of DNA.
What happens during the extension stage of PCR?
The temperature is increased to the optimum for DNA polymerase to build the complementary strands, producing new identical double-stranded DNA molecules.
Define thermal cycler.
Thermal cycler is the PCR machine that automatically provides the optimal temperature for each stage and controls the length of time spent at each stage.
In each PCR cycle the mass of DNA is , so amplification occurs very quickly.
In each PCR cycle the mass of DNA is doubled, so amplification occurs very quickly.
During denaturation, DNA is heated to break the bonds between the two strands.
During denaturation, DNA is heated to break the hydrogen bonds between the two strands.
True or False?
PCR produces genetically varied copies of a DNA fragment.
False.
PCR produces many identical copies of a DNA fragment; the copies are not varied.
True or False?
During the annealing stage of PCR, the temperature is decreased so that primers can bind to the DNA.
True.
Lowering the temperature allows the DNA primers to anneal to the ends of the single-stranded DNA.
Give some uses of the DNA produced by PCR.
DNA profiling (e.g. identifying criminals or determining paternity)
Phylogenetic analysis
Transforming bacteria during genetic modification
Define bacterial transformation.
Bacterial transformation is the introduction of foreign DNA into bacterial cells; it is a genetic engineering technique used to modify the genome of bacteria.
Define vector.
A vector is something used to carry a DNA fragment into a host cell, such as a bacterium; plasmids are commonly used as vectors in bacterial transformation.
What does bacterial transformation introduce into bacterial cells?
Foreign DNA (DNA that did not originate in that bacterium).
Bacteria that have taken up new DNA are said to have been .
Bacteria that have taken up new DNA are said to have been transformed.
True or False?
Bacterial transformation introduces foreign DNA into bacterial cells.
True.
Bacterial transformation is defined as the introduction of foreign DNA into bacterial cells.
Why does the universal genetic code make transformed bacteria useful?
Because the genetic code is universal across organisms, transformed bacteria can read and express genes from other species, allowing them to produce non-bacterial proteins such as human insulin.
Why are plasmids useful in bacterial transformation?
Plasmids are small DNA molecules separate from the main bacterial chromosome, so they can act as convenient DNA vectors to carry foreign DNA into bacterial cells.
Give one example of a useful product made by transformed bacteria.
Human insulin — produced after the human insulin gene is introduced into bacterial cells.
How does bacterial transformation support gene cloning?
Transformed bacteria reproduce, producing many identical cells that all carry copies of the introduced DNA fragment. This propagates the DNA fragment, making many copies for study.
True or False?
There are major ethical concerns over manipulating bacterial DNA compared with other organisms.
False.
There are no ethical concerns over manipulating bacterial DNA, which is one reason bacteria are widely used in genetic engineering.
Bacterial transformation is the introduction of DNA into bacterial cells.
Bacterial transformation is the introduction of foreign DNA into bacterial cells.
Define DNA sequencing.
DNA sequencing is a technology that determines the order of nucleotide bases in an organism's DNA.
Define DNA fingerprint.
DNA fingerprint is a unique pattern of DNA fragments produced by many sequencing techniques, which allows direct comparison of DNA sequences from different samples.
What does DNA sequencing allow scientists to identify?
The nucleotide base sequence of an organism's genetic material.
Many sequencing techniques produce a , a unique pattern of DNA fragments used to compare samples.
Many sequencing techniques produce a DNA fingerprint, a unique pattern of DNA fragments used to compare samples.
How have advances in technology changed DNA sequencing?
They have enabled rapid sequencing methods, allowing scientists to sequence whole genomes very quickly.
True or False?
Most modern DNA sequencing methods are automated rather than interpreted manually.
True.
Most sequencing is now automated, and the data can be entered into computer programs that compare the base sequences of different organisms.
State four uses of DNA sequence data.
Forensic identification
Phylogenetic analysis
Personalized medicine
Organism identification
How is DNA sequence data used in forensic identification?
DNA samples are matched to individuals by comparing their sequences.
How is DNA sequence data used in phylogenetic analysis?
Sequences are compared between species to study their evolutionary relationships.
How is DNA sequence data used in personalized medicine?
Mutations are identified so that targeted treatments can be designed for a patient.
For organism identification, amplified DNA fragments can be sequenced and compared with to classify or identify species.
For organism identification, amplified DNA fragments can be sequenced and compared with databases to classify or identify species.
True or False?
The detailed steps of DNA sequencing techniques must be memorized for the AP Exam.
False.
The details of DNA sequencing techniques are not required for the AP Exam; you only need to understand what sequencing does and how the data are used.
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