Protein expression
This page has four parts, in the order you use them. Part 1 is what you need to know. Part 2 says what to do, in plain English. Part 3 shows the work done once on a case that is not yours. Part 4 is your own work and where to turn it in.
Open your materials, follow the steps, then turn in your work.
Explain how a host cell expresses the inserted gene to produce the target protein.
Optional: listen or watch a unit review▸
Part 1 of 4 · Background and definitions▸
💡 Big idea: Genetic evidence can support an inheritance, sequence, or expression explanation, but penetrance, regulation, environment, family structure, and test uncertainty can limit the conclusion.
- • Expression requires the inserted gene to have a promoter the host cell recognizes.
- • Temperature, nutrient availability, and inducer concentration each affect mRNA and yield.
- • , green fluorescent , is a jellyfish protein that glows green under ultraviolet light; its fluorescence, or activity, is used as a visible proxy for successful expression.
Molecular workflows use controls and complementary separation or detection steps to evaluate a target, while each band, , or remains limited by method resolution and sample quality.
Genetic evidence can support an inheritance, sequence, or expression explanation, but penetrance, regulation, environment, family structure, and test uncertainty can limit the conclusion.
Driving question: Your bacteria from last class carry the human gene, but a can hold the gene and still make almost no . What has to happen inside the cell for the gene to actually turn into product?
What you already know: Molecular workflows use controls and complementary separation or detection steps to evaluate a target, while each band, , or remains limited by method resolution and sample quality.
New idea: Genetic evidence can support an inheritance, sequence, or expression explanation, but penetrance, regulation, environment, family structure, and test uncertainty can limit the conclusion.
Visual or model: No figure is attached to this lesson. The readings, the worked example and E1 to E3 carry the evidence.
- Observe or measure the relevant feature in expression.
- Organize the observation with a stable evidence ID.
- Apply this rule: Stored information can be copied, read, and converted into a functional product.
- Choose the option the evidence supports and state the limit of the conclusion.
Real biomedical example: Today the medical interventions team uses expression to make a bounded evidence decision. A classroom , pedigree, or molecular model does not establish a real person's diagnosis, prognosis, ancestry, identity, or reproductive outcome.
What the evidence supports: E1 to E3 support the daily take-home when the response meets the stated success criteria.
What it cannot prove: The package does not support claims beyond this lesson's or any real patient diagnosis.
- • : A small, circular piece of that lives apart from a bacterium's main and is used in the lab to carry a chosen gene into a cell.
- • : An that joins two pieces of together by sealing the gap in their backbone, vital in genetic engineering.
- • : The process by which a bacterial cell takes up foreign , such as a , from its surroundings and begins using those new genes.
- • expression: The process of turning a gene on so its instructions are used to make RNA and , deciding when and where a gene is active.
Use it now: Choose one decision option. Cite E1 and E3, then explain how the rule connects the evidence to your choice. This is thinking practice for the one turn-in named under Turn in, not a second submission.
Go further, optional: The source links below are optional enrichment. Every fact required for today's local evidence decision appears in this lesson package.
National Human Genome Research Institute is the source this lesson's claim is checked against: Talking Glossary of Genomic and Genetic Terms
Limit: A classroom , pedigree, or molecular model does not establish a real person's diagnosis, prognosis, ancestry, identity, or reproductive outcome.
Stored information can be copied, read, and converted into a functional product.
Limit: Genes are regulated biological sequences, not conscious instructions, and one gene rarely determines a whole trait alone.
You can describe how a host cell expresses an inserted gene.
Limit: E3 defines the classroom product or success criterion. It is not independent scientific evidence and cannot justify a clinical or causal claim.
Today's decision · Simulated classroom evidence scenario
Your role: medical interventions team member
Decision: Your team must decide what the evidence from expression supports before submitting the notebook record named on today's page.
- • Record the yield as fine and move on, since this carries the human gene and already makes the .
- • Measure from cultures grown under different conditions, because one alone cannot show what changes the yield.
- • Explain the low yield by checking and , since growth conditions can turn output up or down.
Response: State one choice, cite at least two evidence IDs, explain the rule that connects them, and add one limitation. Use it inside the one turn-in named under Turn in; it is not a separate submission.
Claim ceiling: Today's evidence supports a classroom claim about expression. It cannot prove causation, diagnose a real patient, or justify action outside this room.
Reason for review: Your team must decide what the evidence from expression supports before submitting the notebook record named on today's page.
Context: Today the medical interventions team uses expression to make a bounded evidence decision. A classroom , pedigree, or molecular model does not establish a real person's diagnosis, prognosis, ancestry, identity, or reproductive outcome.
- • T1: Read the expression notes in the PLTW course shell and define expression.
- • T2: Trace and of the inserted gene in the host cell.
- • T3: Explain why growth conditions can raise or lower how much is made.
- • T4: Identify one sign that expression worked in the practice expression data on this page.
- • T5: Add your expression notes to your Unit 4 PLTW tracker evidence.
- • E1: National Human Genome Research Institute is the source this lesson's claim is checked against: Talking Glossary of Genomic and Genetic Terms
- • E2: Stored information can be copied, read, and converted into a functional product.
- • E3: You can describe how a host cell expresses an inserted gene.
Measurements: Use only the measurements, units, graph, or counts supplied in today's task. No additional patient measurement is implied.
Uncertainty: This is a composite classroom scenario. Missing history, measurements, or confirmation tests remain unknown and limit the conclusion.
Students often think a polished answer about expression is trustworthy even when its evidence source, comparison, or limitation is missing. The trap: Presentation quality cannot raise the evidence level. A classroom , pedigree, or molecular model does not establish a real person's diagnosis, prognosis, ancestry, identity, or reproductive outcome.
- CER:
- Claim, Evidence, Reasoning: make a claim, back it with evidence, explain your reasoning.
- SOP:
- Standard Operating Procedure, the exact steps to follow (especially in a lab).
- Tracker:
- Your PLTW progress log where you record completed evidence.
- myPLTW:
- The PLTW course site where you do the online activities. Find it in Clever with your Microsoft sign-in, right next to Schoology.
Tap the speaker to hear a term. Add two of these to your notebook glossary with a definition and an example in your own words.
Pick just 2 or 3 words from today and make them yours: write what each one means in your own words, name the context clue or evidence that helped, then give one example from what you actually did in Protein expression. Try your own words first; the glossary is there if you get stuck. This is voluntary and counts as extra credit, so keep it short.
Saved on this device. Show Mr. Mendoza or add these to your notebook glossary to claim the extra credit.
Part 2 of 4 · Directions in plain English▸
2.1 Open your materials
Use the materials named in the first step below. Open lesson resources.
Practice expression check (made-up numbers for practice, not from this class)
Four practice E. coli cultures carrying the GFP gene behind an arabinose-switched promoter, grown 16 hours
| Practice culture | Plasmid | Arabinose added? | Temperature it grew at | Green glow under UV | Fluorescence reading (arbitrary units) |
|---|---|---|---|---|---|
| C1 | Recombinant plasmid | Yes | 30 degrees C | Bright | 820 |
| C2 | Recombinant plasmid | No | 30 degrees C | None | 35 |
| C3 | Recombinant plasmid | Yes | 42 degrees C | Faint | 210 |
| C4 | No plasmid | Yes | 30 degrees C | None | 30 |
2.2 Start the work
Read the expression notes in the PLTW course shell and define expression.
Show all 5 required steps
- Read the expression notes in the PLTW course shell and define expression.
- Trace transcription and translation of the inserted gene in the host cell.
- Explain why growth conditions can raise or lower how much protein is made.
- Identify one sign that expression worked in the practice expression data on this page.
- Add your expression notes to your Unit 4 PLTW tracker evidence.
Lost your place? Reopen today's Protein expression record. Find the last completed evidence ID, check it against the claim ceiling, and continue with the first unfinished step rather than restarting the whole task.
- 0-10Read expression notes; define expression in own words
- 10-28Trace of inserted gene; annotate promoter role
- 28-45Trace ; annotate ribosome reading human mRNA in bacteria
- 45-58List two growth conditions that affect yield; explain mechanism
- 58-70Identify expression evidence in the practice expression data on this page; write one sign
- 70-80Add notes to tracker; preview Friday quiz topics
- • Your bacteria now carry the recombinant , but carrying is not the same as making .
- • Expression is the process that turns that into a usable product.
- • Today you trace the path from inserted gene to finished and find the levers that control yield.
- • mechanics are central to the Molecular and Genetic Technology domain on the WebXam.
PLTW connection and today's work
Open Activity 4.1.2 Protein Factories in myPLTW and trace transcription and translation of the inserted gene to explain protein expression in the host cell.
Today's stopping point: Workflow data table should be done; annotated expression notes due today.
PLTW activity titles identify the course connection. If your account will not open, use the posted materials for today and tell Mr. Mendoza. Do not mark an online activity complete unless you completed it.
Use the turn-in directions in Part 4 of this page. Do not create a second submission unless your teacher asks for one.
Show another explanation or a smaller first step
Need help? Choose a starting point
Part 3 of 4 · Worked example▸
This is a parallel case, not your own. Read it for the order of the work, then do your own in Part 4.
Parallel case, not today's data: a practice E. coli culture carries an inserted gene for an enzyme that turns a colorless test chemical blue. The gene sits behind a promoter that switches on only when the inducer IPTG is added.
What expression means: expression is the cell reading the inserted gene and using it to build the protein.
Tracing the steps:
1. Transcription: RNA polymerase binds the promoter in front of the inserted gene and copies the gene into mRNA. With no IPTG, the promoter stays switched off and little mRNA is made.
2. Translation: ribosomes read the mRNA codons and join amino acids into the enzyme, which folds into its working shape.
Two conditions that change yield in this parallel case:
- Inducer: with IPTG added the promoter is switched on, so far more mRNA and enzyme are made.
- Aeration: a flask shaken fast has more oxygen, so the cells grow denser and make more enzyme in total than a still flask.
Evidence expression worked (parallel practice data): the induced, shaken culture turned the test chemical deep blue in 10 minutes; the culture without IPTG stayed nearly colorless. The color is made by the enzyme, so the difference between the two cultures is evidence that the inserted gene was expressed only when switched on.
How to use this: trace your own inserted gene the same way, and take your evidence from the practice expression data on today's page.
This model shows the level of evidence and organization needed to complete: Models the expression notes on a parallel practice culture that makes a different reporter protein: the transcription and translation trace, two conditions that change yield, and one piece of expression evidence read from practice data.
- Date and label the entry.
- Record the procedure, observation, or design decision clearly.
- End with what the evidence means and the next step.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Add your expression notes to your Unit 4 PLTW tracker and submit in Schoology.
A library keeps a master plan protected while working copies guide production at different stations.
- Why protect the master copy?
- What information moves?
- Where can an error change the final product?
Stored information can be copied, read, and converted into a functional product.
Genes are regulated biological sequences, not conscious instructions, and one gene rarely determines a whole trait alone.
- • Master plan maps to .
- • Working copy maps to RNA.
- • Production output maps to or a regulated cell function.
Part 4 of 4 · Your work▸
Check your work before submitting
- You'll be able to describe how a host cell expresses an inserted gene.
- You'll be able to name a condition that changes protein yield.
4.1 Turn in your work
DueCheck the Schoology assignment for this day- Hand in
- Annotated notes tracing transcription and translation of the inserted gene, two yield-affecting conditions, and one piece of expression evidence from the practice expression data on this page.
How to submit and name your file
Submit as one PDF in Schoology.
In Schoology, open your course and the assignment for this lesson. Attach your file, select Submit, and check that it appears in the submission.
PDF upload helpYou get two school days for every day you were absent, so this deadline moves with you.
Today's lesson is in Schoology
Each school day has one lesson page in Schoology that holds everything for the day: the goal, the story so far, every table and data value, the numbered steps, and what to turn in. Open it first and work from it. The other rows for this day, if any, are the score line for a paper quiz or test and the John Carroll debate item; they do not add work. Check Schoology for each deadline.
- Today's Lesson · Tue 12/8 · Wk16 · Identify a pathogen by its DNA, then Koch's postulates and pathogen types(today's lesson page: the goal, the data, the steps, and what to turn in are all on it)
Link will not open? Open Schoology, choose your course and section, and find the title shown above.
- CompleteEvery required part of the artifact is present, nothing left blank.
- AccurateThe science and the data are correct and match the evidence.
- Scientific reasoningYou explain your claim with evidence and reasoning (CER), not just an answer.
- Professional communicationClear, organized, labeled, and written the way a clinician or scientist would.
- SubmittedGo to Schoology to turn this in. Submit one PDF. Schoology attaches your name to your upload; on the page itself, write your period and code. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf. If you cannot get in, see Mr. Mendoza. Do not skip the work.
How this lesson connects
Keep using what you learned last class: Molecular workflows use controls and complementary separation or detection steps to evaluate a target, while each band, fraction, or colony remains limited by method resolution and sample quality. Today: Genetic evidence can support an inheritance, sequence, or expression explanation, but penetrance, regulation, environment, family structure, and test uncertainty can limit the conclusion.
Practice: try a question, then check your answer▸
Claim ceiling for this check: Today's evidence supports a classroom claim about expression. It cannot prove causation, diagnose a real patient, or justify action outside this room.
A student treats one classroom result about protein expression as proof. What must the student add before the conclusion is defensible?
Write an answer and pick a confidence to unlock the key.
Fast retrieval with instant answers, not the commit-then-reveal check above. Try each from memory first: write what you remember about the earlier units, then check yourself here.
Missed class or ready for more?▸
Optional practice for this unit's lab skills. Nothing in it is due today.
What today's skills lead to. These are real health-science careers this course builds toward. Tap one to see, on the US Department of Labor's O*NET site, what the job actually involves, what it pays, and how fast it is growing.
Today is individual work you can do from home: complete the same target above, then submit your Notebook check.
Go to Schoology to turn this in. Submit one PDF. Schoology attaches your name to your upload; on the page itself, write your period and code. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf. If you cannot get in, see Mr. Mendoza. Do not skip the work.
Class still runs. Complete today's work as this page describes (it is self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
Genetic Science Learning Center: CloningThe optional extra-credit track is open. Complete reserved-unit work from home, including virtual labs, for extra credit. Each item shows its correct submission route.
Open the extra-credit trackSources: slides, readings, and resources▸
The deck carries the prior idea forward, lets you inspect an analogy, maps the rule to biology, and ends with the same evidence decision and exit ticket used on this page.
Classroom documents for this lesson are posted in Schoology. Open Clever, then Schoology, and find each one by the name shown on its card.
Use this if you were absent, got stuck, or need another pass before you submit the lesson artifact.
Use this if you were absent, got stuck, or need another pass before you submit the lesson artifact.
Use this if you were absent, got stuck, or need another pass before you submit the lesson artifact.
Sign in to Clever with your district Microsoft account to open Schoology or myPLTW. Follow today's posted steps. If myPLTW will not open, use the posted alternative and tell Mr. Mendoza. Turn in your completed work through the Schoology assignment.
This week
My Progress dashboard