Vectors in Genetic Engineering

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Questions and Answers

What is the primary function of a vector in genetic engineering?

To amplify host chromosomes.

To provide energy to host cells.

To carry foreign DNA into host cells. (correct)

To degrade unwanted DNA.

Which characteristic is NOT essential for a vector?

Contains marker genes for identification.

Contains restriction sites for cutting DNA.

Capable of self-replication.

Must be larger than the host DNA. (correct)

How is the insertion of a vector into a bacterial cell commonly referred to?

Transfection.

Translocation.

Transduction.

Transformation. (correct)

What role do genetic markers play in recombinant DNA technology?

They help identify transformed cells. Signup and view all the answers

What type of vector is specifically designed to carry foreign DNA to a host without expressing it?

Cloning vector. Signup and view all the answers

What is a common genetic marker used in plasmids?

Gene for antibiotic resistance. Signup and view all the answers

Which of the following statements about recombinant DNA is inaccurate?

It is not capable of replication. Signup and view all the answers

Why are vectors often circular in structure?

To reduce the likelihood of being broken down. Signup and view all the answers

What is a primary characteristic of plasmids?

They replicate independently of the bacterial chromosome. Signup and view all the answers

Which of the following is not typically included in synthetic plasmids?

Ribosomal RNA genes Signup and view all the answers

What size of DNA inserts can plasmids typically accommodate?

Up to 20 kb Signup and view all the answers

What mechanism allows bacteriophage lambda to deliver its genome into bacterial cells?

Transduction Signup and view all the answers

Which of the following statements about bacteriophage lambda is false?

It can only deliver small DNA segments. Signup and view all the answers

What is the role of a selectable marker in a plasmid?

To provide a resistance trait against environmental stressors. Signup and view all the answers

In which type of cell are plasmids commonly found?

Bacterial cells Signup and view all the answers

Which cloning vector can accommodate DNA fragments up to 20 kb?

Bacteriophage lambda Signup and view all the answers

What is the primary purpose of an expression vector?

To facilitate the transcription and protein expression of a transgene. Signup and view all the answers

Which type of vector can replicate in E. coli and yeast?

Shuttle vectors Signup and view all the answers

What is the size of Ti vectors typically isolated from Agrobacterium tumefaciens?

200 kb Signup and view all the answers

What induces the lambda prophage to exit from the host chromosome?

Damage to the carrying cell Signup and view all the answers

What does T-DNA from the Ti plasmid encode for?

Synthesis of auxin hormone. Signup and view all the answers

What is the maximum DNA fragment size that a cosmid can carry?

45 kb Signup and view all the answers

Which of the following vectors is likely to be circular?

BACs Signup and view all the answers

What is one of the main advantages of yeast artificial chromosomes (YACs) over bacterial artificial chromosomes (BACs)?

Ability to express proteins needing post-translational modifications Signup and view all the answers

What range of DNA fragment sizes can bacterial artificial chromosomes (BACs) clone?

75 to 300 kb Signup and view all the answers

What is the significant outcome of removing auxin from Ti vectors?

They can be used to deliver genes into plant cells without causing tumors. Signup and view all the answers

Which vector type is characterized as a cloning vector compatible with multiple organism types?

Shuttle vector Signup and view all the answers

What are human artificial chromosomes (HACs) designed for?

Creating new chromosomes in human cells Signup and view all the answers

What is the main function of auxin in the context of Ti vectors?

Inducing cell division and enlargement. Signup and view all the answers

Which type of vector is known to be a circular virus?

M13 Signup and view all the answers

In the context of cloning, what is a key feature of plasmids?

They replicate autonomously within E. coli. Signup and view all the answers

What is the size range of DNA fragments that yeast artificial chromosomes (YACs) can accept?

200 kb - 3000 kb Signup and view all the answers

Study Notes

Vectors

Vectors are small DNA molecules used to carry foreign DNA into host cells for replication and expression.
Common vectors are derived from viruses or bacterial plasmids.
Recombinant DNA describes a vector containing foreign DNA from a different organism.
Transformation (bacterial cells) or transfection (eukaryotic cells) refers to inserting a vector into a target cell.

Essential Characteristics of a Vector

Capable of self-replication within the host cell.
Contains restriction sites for insertion of target DNA.
Small size compared to the host chromosome for easy isolation.
Circular structure (or closed loop) to prevent degradation.
Contains marker genes for identifying cells carrying the vector.
Easily isolable from the host cell.

Genetic Markers

Used to identify transformed cells (those that successfully incorporated the vector).
Often a gene for antibiotic resistance is used as a marker.
Bacterial cells carrying the marker will survive in a medium containing the antibiotic, while normal cells die.
Successful vectors are grown in a medium with an antibiotic.

Types of Cloning Vectors

Plasmids:
- Small, circular DNA molecules found in bacterial cytoplasm.
- Replicate independently of the bacterial chromosome.
- Useful for smaller DNA inserts (less than 20 kb).
- Synthetic plasmids can be engineered to include an origin of replication.
Bacteriophage lambda (λ):
- Viruses that infect bacteria.
- Can deliver large DNA segments to bacterial cells.
- Contains a double-stranded linear DNA genome with approximately 50,000 nucleotide pairs.
- Can multiply in the cell via a lytic pathway or a latent prophage state.
- DNA entrance and exit from bacterial chromosome via site-specific recombination.
Cosmids:
- Hybrids of phages and plasmids.
- Can carry medium-sized DNA fragments (up to 45 kb).
- Replicate like plasmids but package DNA in a phage-like manner.
Bacterial Artificial Chromosomes (BACs):
- Simple plasmid-based vectors.
- Designed for large DNA fragments (75-300 kb).
- Incorporated marker genes and stable origins of replication.
Yeast Artificial Chromosomes (YACs):
- Miniature chromosomes that grow in E. coli and yeast cells.
- Can hold large DNA fragments (200 kb–3000 kb) useful for cloning or physical genome mapping.
- Suitable for complex genomes and expression of proteins requiring post-translational modifications.
Human Artificial Chromosomes (HACs)/Mammalian Artificial Chromosomes (MACs):
- Micro-chromosomes suitable for introducing new genes.
- HACs have a range of 6 to 10 Mb.
- Useful for studying gene expression in human cells.
Shuttle vectors: can replicate in two or more organisms.
Ti vectors: used to transfer genes into plants, derived from Agrobacterium tumefaciens.

Expression Vectors

Specifically designed to express the transgene.
Contain a promoter sequence that initiates transcription of the desired gene.

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Description

Explore the role of vectors in genetic engineering through this quiz. Learn about the characteristics of vectors, their uses in transformation and transfection, and the importance of genetic markers. Test your understanding of how vectors facilitate the incorporation of foreign DNA into host cells.