Question

Recombinant proteins are often produced on a large scale using

• A. Conventional chemical methods
• B. Plant cells
• C. Microbial systems
• D. Inorganic catalysts

Hint:

• Recombinant protein production involves expressing a cloned gene in a host organism.
• Common host systems for large-scale production:
  • Microbial systems (bacteria like E. coli, yeasts like S. cerevisiae or P. pastoris) - often high yield, low cost.
  • Mammalian cell cultures (e.g., CHO cells) - for complex proteins requiring human-like modifications.
  • Plant cells/Transgenic plants.
  • Insect cell cultures.

Answer 1

The Correct Option is C

Recombinant proteins are proteins produced by recombinant DNA technology, where a gene encoding the desired protein is inserted into a host organism's expression system. For large-scale production, various host systems are used.

• (c) Microbial systems: This is a very common and widely used approach. Microorganisms like bacteria (especially \E. coli), yeast (Saccharomyces cerevisiae, Pichia pastoris), and fungi are extensively used as hosts for large-scale production of recombinant proteins due to their rapid growth, ease of genetic manipulation, high yields, and relatively low cost of cultivation in fermenters/bioreactors. Many therapeutic proteins (e.g., insulin, growth hormone) and industrial enzymes are produced this way.
• (b) Plant cells (or whole plants): Plant-based systems (molecular farming) are also used for producing some recombinant proteins. They offer advantages like scalability and potentially lower cost for certain proteins, but protein folding and post-translational modifications might differ from mammalian systems.
• Mammalian cell cultures: Also widely used, especially for therapeutic proteins that require complex post-translational modifications similar to those in humans (e.g., monoclonal antibodies). However, they are generally more expensive and complex to culture than microbial systems.
• Insect cell cultures (using baculovirus expression systems): Another option.
• (a) Conventional chemical methods: While peptides can be synthesized chemically, large complex proteins are typically produced biologically using recombinant DNA technology, not by conventional chemical synthesis on a large scale.
• (d) Inorganic catalysts: These are used in chemical reactions, not for producing proteins. Enzymes (which are proteins) are biological catalysts.

Considering "often produced on a large scale," microbial systems (bacteria and yeast) are workhorses for many recombinant proteins due to cost-effectiveness and scalability. While mammalian and plant cells are also important, microbial systems are a very prominent and often preferred choice for large-scale production of many recombinant proteins. Among the given options, "Microbial systems" is the most fitting answer for common large-scale production. \[ \boxed{\text{Microbial systems}} \]