Molecular Biology: Cloning Vectors and E. coli Nomenclature

Flashcards summarizing key concepts from a lecture on Molecular Biology, focusing on cloning vectors and E. coli genetic nomenclature.

What is the approximate number of genes in a typical E. coli genome?

Approximately 4500 genes.

What does 'gyrA96' denote in E. coli genetic nomenclature?

It indicates a mutation in DNA gyrase subunit A that leads to an amino acid substitution.

What happens when a mutation occurs at the gyrA gene?

It may provide resistance to the antibiotic nalidixic acid.

What is a plasmid?

A small, circular DNA molecule used in cloning to carry foreign genes.

What is the role of Cloning Vectors?

They are used to clone genes or regions of interest.

What does a recombinant plasmid do?

It contains a gene of interest inserted into a plasmid.

What is insertional inactivation?

A technique to disable a gene by inserting DNA into it, preventing its function.

How is blue-white screening used in cloning?

To identify recombinant plasmids based on the color of colonies; white colonies are positive for insert.

What does the term 'allele' refer to?

A variant of a gene that may affect the phenotype in varying degrees.

What is a mutation?

A change in nucleotide sequence that can affect protein sequence and function.

What is a key feature of the pBR322 plasmid?

It carries antibiotic resistance genes, allowing for selection of transformed cells.

What is the function of the lac operon in E. coli?

It regulates the metabolism of lactose.

What is the purpose of a selectable marker in plasmid vectors?

To identify cells that contain the plasmid.

What does pUC18 typically feature?

High copy number and a multiple cloning site allowing for flexible cloning.

How does X-gal work in blue-white screening?

It differentiates Lac+ (blue) from Lac- (white) colonies based on β-galactosidase activity.

Why are plasmids useful in molecular biology?

They facilitate cloning, expression of proteins, and gene manipulation.