The question asks about the role of calcium treatment in the transformation of bacterial cells. Transformation is a process where bacterial cells take up foreign DNA from their environment. This process is often inefficient in natural conditions and requires specific treatments to make the bacterial cells competent, meaning they can readily take up DNA.
Correct Option: C) To increase membrane permeability. Calcium treatment, typically with calcium chloride, makes the bacterial cell membrane more permeable to allow the uptake of foreign DNA (e.g., plasmids) during transformation. This is crucial for genetic engineering techniques.
The question asks to define "downstream processing" in the context of biotechnology. This term refers to the steps taken after the initial fermentation or cell culture to obtain a pure, functional product.
B) Separation and purification of the product — This accurately describes downstream processing, which involves isolating and purifying the desired biotechnological product from the complex mixture in which it was produced.
The question asks about the specific function of the origin of replication (ori) in a cloning vector. Understanding the basic components and their roles in a cloning vector is crucial for answering this question.
Therefore, the primary function of the origin of replication in a cloning vector is to initiate DNA replication.
B) It initiates replication of DNA. The origin of replication (ori) is a specific DNA sequence that serves as the starting point for DNA replication. In a cloning vector, the presence of an ori ensures that the vector, along with the inserted foreign DNA, can replicate independently within the host cell, producing multiple copies.
The question asks to identify the correct statements regarding genetic engineering and biotechnology applications. We need to evaluate each statement based on current scientific understanding and technological capabilities in genetics and stem cell research.
D) 1, 2 and 3. All three statements describe scientifically plausible and, in many cases, demonstrated applications or capabilities in the field of genetic engineering and stem cell research, even if some are ethically contentious or still in early research phases.
The question asks to identify the gene that is inactivated during insertional inactivation, a technique used in molecular cloning to distinguish recombinant cells from non-recombinant cells. This method relies on inserting foreign DNA into a specific gene within a plasmid, thereby disrupting its function. The disruption of this gene's function leads to a detectable change in phenotype, allowing for the identification of recombinants.
Correct Option: C) β-galactosidase. In insertional inactivation, the foreign DNA is inserted into the gene encoding β-galactosidase (part of the lacZ gene). This insertion inactivates the gene, preventing the production of functional β-galactosidase. As a result, recombinant colonies appear white on a medium containing X-gal, while non-recombinant colonies appear blue.
The question asks about the specific type of DNA sequences that restriction enzymes recognize to perform their cutting action. Understanding the function and specificity of restriction enzymes is key to answering this question.
Correct Option: C) Palindromic sequences. Restriction enzymes are highly specific and recognize particular palindromic sequences of DNA, typically 4-8 base pairs long, and cleave the DNA within or near these sites. This property is fundamental to their use in genetic engineering.