Question

name: ella leininger period: 5 due date: 11 - 18 - 25
4.1.2 protein factories - conclusion questions
complete: __ correct: on time: total score: __/4

1. explain why it is necessary to use the same restriction enzyme to cut the desired gene from the source and to cut the plasmid. include a drawing or diagram in your answer.

plasmid
g a
c t
gene is complementary
using the same gene is necessary because the \sticky ends\ need to match in order to become recombinant dna. in order to have matching ends they need to be cut by the same enzyme.

1. how do the results of this experiment illustrate the relationship between dna, proteins, and a trait?
2. what advantage would there be for an organism to be able to turn on or off particular genes in response to certain situations?

Explanation:

1. Restriction enzymes cut DNA at specific sequences. Using the same enzyme on the gene and plasmid ensures complementary "sticky ends" (e.g., if the enzyme cuts plasmid DNA like \( \text{G} \vert \text{A} \) and \( \text{C} \vert \text{T} \), the gene cut by the same enzyme will have complementary overhangs). These sticky ends can then anneal (bind) together via hydrogen bonds between complementary base - pairs, allowing for the formation of recombinant DNA.
2. DNA contains the genetic information (genes). In the experiment, when a specific gene (from DNA) is inserted into a plasmid (a form of DNA) and introduced into a host (like bacteria), the gene is transcribed into mRNA and then translated into a protein. The presence or absence of the protein (e.g., a fluorescent protein in some cases) shows a trait (like fluorescence). So, DNA provides the code (gene), which is used to make a protein, and the protein is responsible for a particular trait.
3. Turning genes on or off (gene regulation) allows an organism to conserve energy and resources. For example, if an organism does not need a particular enzyme (protein product of a gene) when a certain nutrient is not available, it can turn off the gene for that enzyme. It also helps in responding to environmental changes. If there is a sudden change in the environment (e.g., presence of a toxin), the organism can turn on genes that produce proteins to detoxify the toxin.

Answer:

1. Using the same restriction enzyme on the gene and plasmid creates complementary sticky ends. These ends can bind (anneal) via base - pairing (e.g., \( \text{A - T} \) and \( \text{G - C} \) bonds) to form recombinant DNA.
2. DNA (genes) is transcribed to mRNA and translated to proteins. Proteins are responsible for traits. In the experiment, the introduced gene (from DNA) leads to protein production (e.g., a trait - related protein like fluorescence).
3. Gene regulation (turning genes on/off) conserves energy/resources (no unnecessary protein production) and enables response to environmental changes (produce proteins as needed).