Describe genetic engineering on a cellular level. In other words, what exactly takes place during genetic engineering that inserts a trait into an organism that did not have that trait before? Give an example

Genetic engineering on a cellular level involves the process of manipulating an organism's genetic material, typically DNA, to introduce specific traits or characteristics that it did not possess naturally. To achieve this, scientists employ various techniques, such as gene insertion, mutation, or removal.

To better understand this process, let's consider an example where a trait is inserted into an organism. Suppose we want to engineer a plant to become resistant to a certain pest. Here's an overview of the steps involved:

1. Identify the desired trait: Determine the specific characteristic that you want to introduce. In our case, it is pest resistance.

2. Source the gene: Find and isolate the gene responsible for conferring pest resistance in another organism. This could involve studying various sources, including other plants or even bacteria.

3. Preparing the vector: Create a delivery system called a vector, typically a plasmid, which acts as a carrier to transfer the desired gene into the target organism's cells.

4. Introduce the gene: Use molecular biology techniques to insert the pest resistance gene into the vector. This is done by cutting both the vector and the gene using enzymes that act as molecular scissors, and then joining them together using another enzyme called DNA ligase. This modified vector containing the desired gene is often referred to as recombinant DNA.

5. Transformation: Introduce the recombinant DNA into the cells of the target organism, in this case, the plant. This can be done through various methods like agrobacterium-mediated transformation or gene gun bombardment. The vector carrying the gene will enter the plant's cells.

6. Integration and expression: Once inside the target cells, the introduced gene integrates into the plant's genome. The plant cells then start reading and expressing the new gene, ultimately resulting in the production of the desired protein — in this case, a protein that provides resistance against the targeted pest.

7. Selection and propagation: Identify and select the transformed cells that successfully express the introduced gene. These cells are then grown into whole plants using tissue culture techniques.

By precisely inserting the pest resistance gene into the plant's genome, we have successfully engineered a modified plant that now possesses the trait of pest resistance. The specific steps may vary depending on the organism and the desired trait, but this generalized process outlines the principles and techniques used in genetic engineering at the cellular level.