The question asks to identify the enzyme responsible for cutting DNA at specific sequences, a crucial step in recombinant DNA technology. We need to recall the functions of various enzymes involved in molecular biology processes.
Correct Option: A) Restriction endonuclease is the enzyme used to cut DNA at specific sequences. These enzymes are naturally found in bacteria, where they serve as a defense mechanism against invading viruses by cleaving foreign DNA.
This question tests knowledge about the specific function of DNA ligase in recombinant DNA technology. Understanding the roles of various enzymes used in genetic engineering is crucial.
Correct Option: C) Join two DNA fragments
The question asks to identify the most widely used cloning vector in bacteria. This requires knowledge of common cloning vectors and their applications, particularly in bacterial systems.
A) pBR322 plasmid is one of the first and most widely used artificial cloning vectors. It is a small, circular DNA molecule that can replicate independently in bacteria (like E. coli). It contains genes for antibiotic resistance (ampicillin and tetracycline), which serve as selectable markers, and several unique restriction enzyme sites, allowing for the insertion of foreign DNA. Its design made it a foundational tool for genetic engineering in bacteria.
The question asks for the specific term used to describe the process of introducing recombinant DNA into a bacterial host cell. This is a fundamental concept in molecular biology and genetic engineering.
B) Transformation is the process by which a bacterial cell takes up naked DNA from its environment. In genetic engineering, this is the most common method used to introduce recombinant DNA (often in the form of a plasmid) into bacterial host cells for cloning or protein expression.
The question asks about the specific enzyme used to amplify DNA in Polymerase Chain Reaction (PCR). PCR is a molecular biology technique used to make many copies of a specific DNA segment. Understanding the function of each enzyme listed in the options is key to identifying the correct answer.
D) Taq DNA polymerase is the enzyme specifically used in PCR to synthesize new DNA strands. Its thermostable nature allows it to withstand the high temperatures required for DNA denaturation in each cycle without losing its activity.
The question asks about the three main steps in each cycle of Polymerase Chain Reaction (PCR). PCR is a molecular biology technique used to amplify a single copy or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. Understanding the sequential steps of a PCR cycle is crucial.
These three steps constitute one cycle of PCR, and the cycle is typically repeated 20-40 times to achieve significant amplification of the target DNA.
A) Denaturation, Annealing, Extension are indeed the three sequential steps that occur in each cycle of the Polymerase Chain Reaction (PCR).