Protein expression
Fri, Dec 4, 2026 · Week 15 · Genetics of Disease (Medical Interventions)
Today's goal: Explain how a host cell expresses the inserted gene to produce the target protein.
What a finished product looks like
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
What expression means: expression is the cell reading the inserted gene and using it to build the target protein.
Tracing the steps:
1. Transcription: the host cell's machinery copies the inserted gene into mRNA, but only if the gene has a promoter the host cell recognizes.
2. Translation: ribosomes read the mRNA and assemble the amino acid chain that folds into the target protein.
Two conditions that change yield:
- Temperature: too high or too low can slow the cell or cause the protein to misfold, lowering usable yield.
- Inducer concentration: adding the right amount of inducer can switch the gene on strongly, raising protein output.
Evidence expression worked: in the sample data, the cells glowed green under UV light. Because GFP fluorescence is a visible proxy for the protein being made, the glow tells me the inserted gene was expressed.
Also due today: Add your expression notes to your Unit 4 PLTW tracker and submit to the course shell.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.