Mutation, HGT, and superbugs
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 mutation and horizontal gene transfer spread resistance genes and create superbugs.
Optional: listen or watch a unit review▸
Part 1 of 4 · Background and definitions▸
💡 Big idea: Resistance genes ride on plasmids that bacteria pass sideways through conjugation, , and transduction, so a susceptible cell can become multi-drug resistant in one transfer, which is why superbugs spread resistance faster than alone ever could.
- • (HGT) moves between bacteria via conjugation ( transfer), (environmental DNA uptake), or transduction (phage-mediated).
- • Because resistance genes often travel on plasmids, a single HGT event can make a previously susceptible bacterium resistant to multiple antibiotics simultaneously.
- • Superbugs (like MRSA and CRE) carry multiple resistance genes acquired through HGT over time; some are now resistant to all available antibiotics.
A isolates single cells so that each descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain.
Resistance genes ride on plasmids that bacteria pass sideways through conjugation, , and transduction, so a susceptible cell can become multi-drug resistant in one transfer, which is why superbugs spread resistance faster than alone ever could.
Driving question: A patient carries a gut bacterium that is harmless but resistant to several antibiotics. How could its resistance genes end up inside a dangerous strain, turning a treatable infection into an untreatable one?
What you already know: A isolates single cells so that each descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain.
New idea: Resistance genes ride on plasmids that bacteria pass sideways through conjugation, , and transduction, so a susceptible cell can become multi-drug resistant in one transfer, which is why superbugs spread resistance faster than alone ever could.
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 today's lesson.
- Organize the observation with a stable evidence ID.
- Apply this rule: A decision is stronger when the test fits the question and its limits are known.
- Choose the option the evidence supports and state the limit of the conclusion.
Real biomedical example: A patient carries a gut bacterium that is harmless but resistant to several antibiotics. How could its resistance genes end up inside a dangerous strain, turning a treatable infection into an untreatable one?
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 set of careful practices used to keep microbes out of a sterile area, protecting samples, cultures, and patients from .
- • : A population of microbes or cells grown on purpose in a nutrient medium so they can be studied, identified, or tested.
- • : A visible cluster of identical microorganisms growing on a plate, all descended from a single original cell.
- • : The slowing or blocking of a process, such as an stopping bacteria from growing or a molecule shutting down an .
- • : A change in the ; some change a enough to cause disease, many do not.
- • : The passing of genes between organisms, often bacteria, without reproduction, a major way spreads.
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.
Antimicrobial resistance can arise through or acquired genetic material and spread under selection, so a resistance explanation requires organism, method, and susceptibility evidence rather than the presence of a gene term alone.
Limit: A classroom model or zone result cannot identify every resistance mechanism or determine treatment for a real patient.
A decision is stronger when the test fits the question and its limits are known.
Limit: Medical decisions also depend on biology, patient context, ethics, and professional judgment.
You can explain and .
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 today's lesson supports before submitting the notebook record named on today's page.
- • Explain the jump as , since a can carry resistance genes sideways into a dangerous strain.
- • Say the dangerous strain must slowly gain its own lucky mutations, one drug at a time, over many generations.
- • Gather organism, method, and susceptibility results first, because naming a resistance gene alone does not show that it moved.
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 today's lesson. 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 today's lesson supports before submitting the notebook record named on today's page.
Context: Resistance genes can move between bacteria, even between different species, on mobile pieces of , so bacteria evolve resistance far faster than alone would allow, which is what makes superbugs so hard to stop.
- • T1: First 10 minutes: read your plate from Monday through the taped lid (never open it). Count the distinct colonies, describe size, color, shape and edges, tally separately, and finish your in your notebook. It goes inside today's one notebook PDF with your HGT work; there is no separate Culturing upload.
- • T2: Define and in your own words.
- • T3: Read how bacteria swap resistance genes even between different strains.
- • T4: Draw how one resistant cell can share a resistance gene with neighbors.
- • T5: Connect this to why superbugs can resist several antibiotics at once.
- • T6: Use your data to imagine how a resistant colony could take over.
- • E1: Antimicrobial resistance can arise through or acquired genetic material and spread under selection, so a resistance explanation requires organism, method, and susceptibility evidence rather than the presence of a gene term alone.
- • E2: A decision is stronger when the test fits the question and its limits are known.
- • E3: You can explain and .
Measurements: No patient measurement is supplied unless it appears explicitly in E1-E3. Do not invent a value.
Uncertainty: This is a composite classroom scenario. Missing history, measurements, or confirmation tests remain unknown and limit the conclusion.
Students often think bacteria become resistant only the way we picture evolution: a lucky appears, and resistant cells slowly out-survive the rest over many generations, one drug at a time. The trap: it misses : bacteria can swap ready-made resistance genes sideways through conjugation ( transfer), (grabbing loose ), or transduction (phage delivery), even between different species, so a susceptible cell can become multi-drug resistant in a single event instead of waiting on its own mutations.
- 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 Mutation, HGT, and superbugs. 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.
2.2 Start the work
First 10 minutes: read your culture plate from Monday through the taped lid (never open it). Count the distinct colonies, describe size, color, shape and edges, tally contamination separately, and finish your data table in your notebook. It goes inside today's one notebook PDF with your HGT work; there is no separate Culturing upload.
Show all 7 required steps
- First 10 minutes: read your culture plate from Monday through the taped lid (never open it). Count the distinct colonies, describe size, color, shape and edges, tally contamination separately, and finish your data table in your notebook. It goes inside today's one notebook PDF with your HGT work; there is no separate Culturing upload.
- Define mutation and horizontal gene transfer in your own words.
- Read how bacteria swap resistance genes even between different strains.
- Draw how one resistant cell can share a resistance gene with neighbors.
- Connect this to why superbugs can resist several antibiotics at once.
- Use your colony data to imagine how a resistant colony could take over.
- Write one sentence linking culturing, resistance, and stewardship.
Lost your place? Check your step: if you have not defined mutation and horizontal gene transfer in your own words, start there; then read how bacteria swap resistance genes across strains, draw one resistant cell passing a gene to a neighbor, and finish by writing one sentence linking your colony data, resistance, and antibiotic stewardship.
- 0-10 minRead your plate through the taped lid: count and describe colonies, tally , finish the
- 10-18 minDefine and in notebook; list the three HGT mechanisms (conjugation, , transduction)
- 18-30 minRead how bacteria swap resistance genes via ; summarize in two sentences
- 30-45 minDraw a diagram: one resistant cell shares a resistance with a neighbor via conjugation; label all parts
- 45-57 minExplain how one HGT event can confer resistance to multiple antibiotics simultaneously; connect to the parts of a bacterium each class attacks (cell wall, ribosome, copying)
- 57-70 minUse your data: if one colony on your plate were resistant, how long and under what conditions would it take over the plate? Write your reasoning
- 70-80 minWrite the linking sentence; photograph the and the HGT pages and submit them as one PDF
- • MRSA (methicillin-resistant Staphylococcus aureus) kills more Americans each year than HIV; it became resistant through exactly the mechanisms you are about to study.
- • Unlike animals, bacteria can pass resistance genes to bacteria of a completely different species; they do not have to wait for reproduction.
- • The counts you record in the first 10 minutes give you a real population to apply these ideas to.
- • Exit goal: one notebook PDF with your finished , a HGT diagram showing a resistance gene moving between cells, and a superbug connection sentence.
PLTW connection and today's work
Open Activity 1.2.4 When Antibiotics Fail in myPLTW and use its reading on how resistance spreads. Your plate from last class is a streak plate, so there are no zones to measure today.
Today's stopping point: Colony data table finished in the first 10 minutes; it and the HGT notebook entry go in today's one PDF.
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.
Course connection
- Activity 1.2.4 When Antibiotics Fail
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.
Definitions in my own words:
- Mutation: a random change in a bacterium's DNA. Once in a while a mutation happens to make the cell able to survive an antibiotic.
- Horizontal gene transfer (HGT): when one bacterium passes a gene to another bacterium instead of to its offspring. Resistance genes can move this way, even between different species.
How one resistant cell shares its gene (conjugation): A resistant cell builds a bridge called a pilus to a neighbor, copies its resistance plasmid, and sends the copy across. Now both cells are resistant.
Why superbugs resist several drugs at once: Resistance genes often ride on the same plasmid. One transfer can hand over resistance to multiple antibiotics in a single step, so a cell can become multi-drug resistant without slowly earning each resistance on its own.
Colony-data scenario: On my plate, imagine one colony on my plate carried a resistance plasmid. If I added an antibiotic, that colony's descendants would survive and the others would die, so over time the resistant colony would take over the whole plate.
Linking sentence: Careful culturing lets us see resistant strains, resistance spreads through mutation and HGT, and that is exactly why stewardship (using antibiotics sparingly and correctly) matters.
This model shows the level of evidence and organization needed to complete: Completes the resistance-mechanism notebook page: definitions of mutation and horizontal gene transfer, a labeled conjugation diagram, a multi-resistance explanation, a colony-data scenario, and a linking sentence.
- 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: Photograph your colony data table and this notebook page and submit them together as one PDF in Schoology.
An airport checkpoint uses an ID check, a metal detector, and an X-ray scanner.
- What can the ID check detect?
- What might set off the metal detector by mistake?
- Why do we need the X-ray if we already checked their ID?
A decision is stronger when the test fits the question and its limits are known.
Medical decisions also depend on biology, patient context, ethics, and professional judgment.
- • The ID check maps to confirming patient identity.
- • The metal detector maps to a rapid, non-specific screening test.
- • The X-ray scanner maps to a detailed, specific diagnostic test.
Part 4 of 4 · Your work▸
Check your work before submitting
- You will be able to explain mutation and horizontal gene transfer.
- You will be able to describe how resistance genes spread between bacteria.
- You will be able to explain how superbugs arise.
4.1 Turn in your work
DueCheck the Schoology assignment for this day- Hand in
- Your finished colony data table (count, size, color, shape, edge, and a separate contamination tally), then the notebook entry: HGT mechanism definitions, conjugation diagram with labeled parts, multi-resistance explanation, colony-data application scenario, and linking sentence connecting culturing to resistance to stewardship.
How to submit and name your file
Photograph the colony data table and the notebook entry and submit them together as one PDF to Wk7 Lab notebook: Mutation, HGT, and superbugs 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.
Find this lesson's Schoology assignments
These are existing assignments for your section. Follow the directions in the assignment you are working on; this list does not add new work. A PLTW Work row repeats on every day of its lesson; submit it once. Check Schoology for each deadline.
- Wk7 Lab notebook: Mutation, HGT, and superbugs(today's turn-in)
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: A streak plate isolates single cells so that each colony descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain. Today: Resistance genes ride on plasmids that bacteria pass sideways through conjugation, transformation, and transduction, so a susceptible cell can become multi-drug resistant in one transfer, which is why superbugs spread resistance faster than mutation alone ever could.
Practice: try a question, then check your answer▸
Claim ceiling for this check: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
A bacterial strain that three antibiotics stopped last week now grows through all three. In between, it was treated with one of those drugs, and only the cells that survived kept dividing. Mutation alone is unlikely to explain resistance to all three. What most likely happened, and by which mechanism could it happen in one step?
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:
CDC Antibiotic ResistanceSources: 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.
Open this when the class reaches this activity and use it to complete the required 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.
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