Microbe Mutations Teacher Guide Microbe Mutations
Teacher Facilitation Guide • 10th Grade Biology
50 MIN LESSON
Learning Objectives
Differentiate between mitosis (eukaryotic) and binary fission (prokaryotic).
Identify mutation and conjugation as the primary mechanisms for genetic variation in asexual organisms.
Model the spread of genetic traits (like antibiotic resistance) via plasmids .
Preparation & Materials
Materials Needed:
"Microbe Mutations" Slide Deck
"Bacterial Battleground" Worksheet
Printed Trait Cards (1 set per class)
Pre-cut 3ft lengths of yarn/string ("Pili")
Stopwatch/Timer
Setup Note:
Cut enough 3-foot lengths of yarn so that roughly half the class can have one. Organize the "Antibiotic Resistance" cards separately—you will start with only 3-5 "infected" students.
Instructional Sequence
1. Warm-up: Binary vs. Mitotic (5 min)
Students complete the Venn diagram on their worksheet. Focus: Binary fission is faster and simpler (no nucleus, no spindle fibers).
2. Video Viewing (10 min)
Watch "Bacteria - Understanding the Bacteria Kingdom" (6:57-8:34). Key Question: If they make identical copies, where does the new DNA come from? (Answers: Random mutation or Conjugation/Pilus transfer).
3. Simulation: Pass the Plasmid (25 min)
Round 0: Assign 3 students the "Resistance" card. Give everyone else "Normal Trait" cards.
The "Pilus": Only students with the "Resistance" card can hold the "Pilus" (yarn). To transfer, they must hold one end, have a partner hold the other, and hand them a duplicate "Resistance" card.
Rounds: Run three 1-minute rounds. At the end of each round, pause to record how many students have resistance.
4. Closure: The Superbug Crisis (5 min)
Discuss: Why is conjugation a nightmare for doctors? How does our simulation explain why MRSA spreads so quickly in hospitals?
Key Discussion Prompts:
Check for Understanding: "Is conjugation a form of reproduction?"Critical Thinking: "What would happen to our colony if we introduced an antibiotic after Round 3?" Microbe Mutations Slides 10th Grade Biology
MICROBE
MUTATIONS
Exploring Genetic Variation in Asexual Organisms
Mutation
Conjugation
Warm-Up: The Copycats
Mitosis
Occurs in Eukaryotes (complex cells)
Involves nucleus & spindle fibers
Multiple linear chromosomes
Binary Fission
Occurs in Prokaryotes (bacteria)
Much faster and simpler process
Single circular chromosome
BIG QUESTION: If they only make identical copies, how do they evolve?
Bacteria: Reproduction & Variation
Watch for the explanation of "Conjugation"
Embedded media
01
How do mutations spread so fast?
02
What is the "pilus" tube for?
The "Upgrade" Strategy
Random Mutation
Mistakes during DNA replication. Because bacteria reproduce in minutes , a "lucky" mutation spreads to billions in days.
Conjugation
The "Bacterial Handshake." One cell sends a small loop of DNA (Plasmid ) to another cell through a bridge called a Pilus .
Pass the Plasmid
We are now a bacterial colony. Some of you have evolved Antibiotic Resistance. The rest of you are vulnerable.
Goal
Spread the Resistance
Time
3 Timed Rounds
The Rules of Engagement
01
THE PILUS
If you have a Resistance Card , you can use a "Pilus" (yarn) to connect to a neighbor.
02
THE TRANSFER
While connected, you give them a COPY of your Resistance card. They are now resistant!
03
LIMITS
You can only connect to ONE person per round. The pilus takes time to build!
The Superbug Threat
When we use antibiotics, we kill the weak bacteria.
But conjugation allows the survivors to share their "defense plans" with everyone else.
Case Study: MRSA
A common bacteria that has traded enough "plasmids" to become immune to almost every standard hospital antibiotic.
Bacterial Battleground Worksheet Bacterial Battleground
Name: ___________________________
Topic: Mechanisms of Genetic Variation in Asexual Organisms
Part 1: The Copying Process
Compare Mitosis (Eukaryotes) and Binary Fission (Prokaryotes) below.
Mitosis
Binary Fission
What do both have in common?
Part 2: Variation Mechanics
1. Mutation
Why are mutations so effective in bacterial populations compared to humans?
2. Conjugation
Draw a simple diagram of two bacteria using a pilus to share a plasmid .
Simulation: Pass the Plasmid
Track the spread of antibiotic resistance in our colony.
Round Resistant Bacteria (Count) Normal Bacteria (Count) START (Round 0) Round 1 Round 2 Round 3
Post-Sim Reflection:
Describe the growth of the resistant population. Was it linear (steady) or exponential (rapid)? Why?
The Superbug Threat
Based on our simulation, explain why doctors tell patients they MUST finish their entire course of antibiotics, even if they feel better after two days.
Plasmid Trait Cards Simulation Simulation Materials: Pass the Plasmid
Print and cut these cards for the classroom activity.
Quick Rules for Students
You are a bacterium. Keep your trait card visible at all times.
If you have a Resistant card, you can use a "Pilus" (yarn) to connect to a neighbor.
Hand them a copy of the Resistant card. They must discard their old card.
You can only build ONE pilus per 1-minute round.
RESISTANT
TRAIT: ANTIBIOTIC SHIELD
PLASMID DNA
RESISTANT
TRAIT: ANTIBIOTIC SHIELD
PLASMID DNA
RESISTANT
TRAIT: ANTIBIOTIC SHIELD
PLASMID DNA
NORMAL
TRAIT: VULNERABLE
STANDARD DNA
NORMAL
TRAIT: VULNERABLE
STANDARD DNA
NORMAL
TRAIT: VULNERABLE
STANDARD DNA
Teacher Setup:
Print multiple copies of this page. You will need one card per student. Ensure you have a stack of "RESISTANT" cards ready to give out as the simulation progresses. Every student starts with a "NORMAL" card except for 3 designated "patient zero" bacteria who start with "RESISTANT" cards.
