Explain that genes to be transferred into an organism may be: • extracted from the DNA of a donor organism • synthesised from the mRNA of a donor organism • synthesised chemically from nucleotides

SouravNovember 1, 2024

Answer

When transferring genes into an organism through genetic engineering, there are several methods to obtain the desired genetic material. Here’s a detailed explanation of the three primary sources from which genes can be derived for this purpose:

1. Extracted from the DNA of a Donor Organism

• Description: This method involves isolating the specific gene of interest directly from the genomic DNA of a donor organism.
• Process:
  • DNA Extraction: The first step is to extract total DNA from the cells of the donor organism using chemical or mechanical methods.
  • Gene Isolation: Once the DNA is extracted, molecular techniques such as polymerase chain reaction (PCR) or restriction enzyme digestion are used to isolate the specific gene that encodes the desired trait.
• Applications: This approach is commonly used when the gene of interest is known and can be directly obtained from an organism that naturally expresses that trait. For example, genes that confer disease resistance in plants can be extracted from wild relatives of cultivated crops.

2. Synthesised from the mRNA of a Donor Organism

• Description: In this method, the gene is synthesized based on the messenger RNA (mRNA) produced by a donor organism. This approach is particularly useful for obtaining genes that are actively expressed in specific tissues or under certain conditions.
• Process:
  • mRNA Extraction: The mRNA is extracted from cells of the donor organism, typically from tissues where the gene is actively expressed.
  • Reverse Transcription: The extracted mRNA is then reverse transcribed into complementary DNA (cDNA) using an enzyme called reverse transcriptase. This cDNA represents the coding sequence of the gene without introns (non-coding regions).
• Applications: This method is advantageous for obtaining genes that are expressed only in certain developmental stages or environmental conditions, such as stress response genes in plants.

3. Synthesised Chemically from Nucleotides

• Description: This method involves chemically synthesizing a gene using nucleotide sequences. It does not rely on extracting genetic material from existing organisms.
• Process:
  • Gene Design: Scientists design a specific nucleotide sequence based on the desired characteristics of the gene. This can include codon optimization to enhance expression in a particular host organism.
  • Chemical Synthesis: The designed sequence is synthesized using automated DNA synthesizers that assemble nucleotides in the correct order to form a complete gene.
• Applications: Chemical synthesis allows for precise control over the genetic sequence, enabling researchers to create novel genes with specific functions or modifications. This method is often used in synthetic biology to design entirely new pathways or functions.