Read the following passage and answer the questions that follow:
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow:
Question: 1
Why are plasmids and bacteriophages used as cloning vectors?
Show Hint
Plasmids and bacteriophages serve as efficient cloning vectors due to their ability to replicate independently in host cells, allowing the amplification of foreign genes.
Step 1: Cloning Vectors.
Plasmids and bacteriophages are used as cloning vectors because they are naturally occurring, small, circular DNA molecules that can replicate independently of the host chromosomal DNA. This allows them to carry and multiply foreign DNA within host cells.
Step 2: Efficiency in Gene Cloning.
Plasmids and bacteriophages can be engineered to carry specific genes and facilitate gene transfer into bacterial cells. This process ensures that foreign genes can be cloned, expressed, and even amplified in large quantities.
Step 3: Features of pBR322.
In the case of plasmids like pBR322, they have multiple cloning sites, antibiotic resistance markers (such as ampicillin resistance), and an origin of replication (ori), which make them efficient and easy to use for gene cloning and manipulation.
Was this answer helpful?
0
0
Question: 2
Identify:(I) The gene in the cloning vector that controls the copy number of the vector. (II) The restriction site - C in the ‘rop’ gene.
Show Hint
The ori gene controls the copy number of the plasmid, while the rop gene helps regulate replication efficiency by interacting with the replication machinery.
Step 1: Gene controlling copy number.
The gene in the cloning vector that controls the copy number of the vector is the replication origin or ori gene. It ensures that the plasmid is replicated a certain number of times within the host cell.
Step 2: The ‘rop’ gene and restriction site.
The restriction site C in the 'rop' gene refers to a specific sequence within the rop (repressor of primer) gene, which helps regulate the replication of the plasmid by interacting with the replication machinery.
Was this answer helpful?
0
0
Question: 3
Identify and name two selectable markers shown in the diagram.
Show Hint
Selectable markers like ampicillin and tetracycline resistance genes allow the identification of successful transformants in a cloning experiment.
Step 1: Selectable Markers.
Two selectable markers typically found in plasmids like pBR322 are ampicillin resistance (amp^R) and tetracycline resistance (tet^R). These genes allow for the selection of cells that have successfully taken up the plasmid by enabling growth in the presence of these antibiotics.
Was this answer helpful?
0
0
Question: 4
Name the two restriction sites each in the two genes you have identified as selectable markers.
Show Hint
Restriction sites in selectable marker genes like amp^R and tet^R are used to facilitate cloning by allowing for the insertion of foreign DNA into the plasmid.
Step 1: Restriction Sites in amp^R Gene.
The amp^R gene commonly has restriction sites such as PstI and EcoRI, which can be used for cloning purposes.
Step 2: Restriction Sites in tet^R Gene.
The tet^R gene commonly has restriction sites like HindIII and BamHI, which can also be used for cloning or inserting foreign DNA.
