10 Questions
What is the primary function of a vector in gene cloning?
To carry a foreign DNA fragment into a host cell
What is the purpose of a selectable marker in a vector?
To enable identification of transformed cells
What type of vector combines elements of plasmids and viruses?
Cosmid
What is the function of an origin of replication in a vector?
To allow the vector to replicate in the host cell
What is the role of restriction enzymes in gene cloning?
To cut the vector and the foreign DNA fragment to create compatible ends
What is the difference between exonucleases and endonucleases?
Exonucleases remove nucleotides from the ends of DNA molecules, while endonucleases cut DNA at specific internal sites
What is the purpose of electroporation in transformation?
To use an electric field to create temporary holes in the cell membrane
What is the purpose of chemical transformation in gene cloning?
To use chemicals to create temporary holes in the cell membrane
What is the purpose of biotransformation in gene cloning?
To use a biological vector to deliver the DNA fragment to the host cell
What is the result of successful transformation in gene cloning?
The foreign DNA fragment is replicated in the host cell
Study Notes
Vectors
- A vector is a small, self-replicating DNA molecule that can carry a foreign DNA fragment into a host cell
- Types of vectors:
- Plasmids: small, circular DNA molecules found in bacteria
- Viral vectors: use a virus to deliver the DNA fragment to the host cell
- Cosmids: hybrid vectors that combine elements of plasmids and viruses
- Key features of vectors:
- Origin of replication: allows the vector to replicate in the host cell
- Selectable marker: allows identification of transformed cells (e.g. antibiotic resistance)
- Cloning site: a region where the foreign DNA fragment can be inserted
Restriction Enzymes
- Restriction enzymes are enzymes that cut DNA at specific recognition sites
- Recognition sites: specific sequences of nucleotides that the enzyme binds to and cuts
- Types of restriction enzymes:
- Exonucleases: remove nucleotides from the ends of DNA molecules
- Endonucleases: cut DNA at specific internal sites
- Uses of restriction enzymes in gene cloning:
- Cutting the vector and the foreign DNA fragment to create compatible ends
- Analyzing the resulting DNA fragments using gel electrophoresis
Transformation
- Transformation is the process of introducing a vector carrying a foreign DNA fragment into a host cell
- Methods of transformation:
- Chemical transformation: uses chemicals to create temporary holes in the cell membrane
- Electroporation: uses an electric field to create temporary holes in the cell membrane
- Biotransformation: uses a biological vector (e.g. virus) to deliver the DNA fragment
- Key factors affecting transformation efficiency:
- Competence: the ability of the host cell to take up the DNA fragment
- Vector design: the choice of vector and its components (e.g. origin of replication, selectable marker)
Ligation
- Ligation is the process of joining the foreign DNA fragment to the vector using an enzyme called DNA ligase
- Types of ligation:
- Sticky-end ligation: uses complementary overhangs created by restriction enzymes
- Blunt-end ligation: uses no overhangs, requiring a different type of ligase
- Key factors affecting ligation efficiency:
- Concentration of DNA fragments and vector
- Temperature and reaction time
- Presence of inhibitors or contaminants
This quiz covers the basics of molecular biology, including vectors, restriction enzymes, transformation, and ligation in gene cloning. Learn about the types of vectors, restriction enzymes, and their applications in genetic engineering.
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