The Unit: An Introduction to Genetics
Ms. Jessica Delaney
Level: 9th -10th Grade Introduction to Biology Class
Time frame: Approximately 45 minutes per class, 9 days
Unit Objectives:
Students will be able to:
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Model the structure of the DNA double helix and the process of DNA replication
Know a gene is a segment of DNA which provides the instructions for making a protein
Describe the similarities and differences between the structure and function of DNA and RNA
Depict and describe protein synthesis through the processes of transcription and translation
Transcribe and translate a set of genes into a protein
Know the sequence of amino acids determine a protein’s structure and function
Day 1 –
DNA Structure
Our DNA Crime Scene Unit Set-Up
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Put students in small groups of about 4. Have the groups choose someone as a leader.
Tell students an inexcusable crime has taken place in the classroom. Ms. Jessica had baked
cookies to share with the class. She arrived in the classroom that morning and set the cookies
down on her desk around 7:45 AM. She then went to the teacher’s lounge to get her much
needed daily caffeine fix. Returning to her room by 8 AM, she noticed the cookies were gone,
not just taken, but eaten on the spot. It looked as though the plate had even been licked clean!
Luckily, her being an amazing Biology teacher, she was able to collect DNA samples from crumbs
on the floor as well as the plate. She is sure one student couldn’t have consumed all the cookies
that fast; there must be a group! In order to solve the case, the class is going to have to learn all
about DNA. By the end of the unit, the students will be able to perform DNA fingerprinting and
identify the cookie eater(s).
Give each group a handout of the basic structure and components in DNA. Have the group read
the handout and answer the questions on the bottom about complementary strands and DNA
base pairing. Small groups will then be able construct their own DNA double helix model from a
box of items at the front of the room. Such as toothpicks, Styrofoam balls, pipe cleaners,
colored marshmallows, string, beads, etc. Students must provide a key with their model or label
the model directly. Each group will receive a sequence of base pairs which must be depicted in
the model.
Assessment:
o Informal- Observation as students construct their models. Checking participation.
o Formal – each group will be graded on if they completed their model as well as if it was
correctly constructed (matching base-pairs), and correctly labeled.
Day 2 –
DNA Replication
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Start the class off with a class activity involving a review of Mitosis and Meiosis. Give the groups
a few minutes to jot down pictures of what happens in each Mitosis and Meiosis. Using the
overhead projector and pre-cut strings have each group take a turn at demonstrating a few
stages of Mitosis and Meiosis. This prepares students to discuss where DNA is at during these
processes.
There will be small group as well as class discussion on DNA functions and why and how DNA
replicates (series of questions posed by teacher). Students will then return to their DNA models
from the previous class and complete DNA Replication, making sure to labeling the old and new
strands. What is the process taking place chemically as well as structurally (breaking of
hydrogen bonds)? Each group will get a couple minutes to present their reconstructed DNA
models to the whole class.
Assessment:
o Informal- Observation of class activity and class discussions
o Formal- Completion of DNA Replication Models, proper structure, proper labeling.
Day 3 –
Interactive Computer Lab on RNA
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Students will work in pairs in the computer lab completing a list of activities provided on a
handout.
First, students will watch the YouTube video Why RNA is just as cool as DNA. Students will
discuss and fill in questions to a worksheet (Where is DNA found in the cell? Where is RNA
found? How are they structurally similar and/or different? What are the functions of RNA?).
Students will also complete the online reading embedded activities from
learn.genetics.utah.edu which takes you through the processes of transcription and translation.
Students will complete the worksheet about protein synthesis (what are start and stop codons,
what does tRNA do, what is a codon?).
Assessment:
o Formal- Students will hand in their worksheets at the end of class. Checked for
completion and level of intelligent thought in questions.
Day 4 –
Protein Synthesis Model
Introduction to Group Research Posters
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Students will begin creating a Research Poster on Protein Synthesis, Protein Identification, and
Associated Diseases and/or Mutations
Using the models constructed for DNA and DNA replication, each group will use the base pairing
sequences of their model to perform transcription and translation. The process will be drawn in
detail on a group poster board which should depict the intermediate steps of RNA polymerase,
tRNA, and the ribosome. Posters should include a visual of where each step is taking place
inside the cell (for instance, DNA replication happens inside the nucleus; once RNA polymerase
and mRNA transcribe the gene, mRNA moves into the cytoplasm). Students may use all of their
notes, handouts, and worksheets finished thus far during the unit to help create the poster.
Along with the visuals, there should be detailed steps and descriptions of how things are
happening. Students must properly identify the start and stop codons in their models in order
to successfully complete the amino acid sequence and create a protein. Once the polypeptide
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chain is translated, students will be given the Protein BLAST coding system handout (uses 1
letter coding to represent each amino acid in a protein chain: P=proline).
Assessment:
o Informal- Observation of groups as they work on the research poster. Checking for
participation from all members.
Day 5 –
Protein Identification and Mutations
Completion of Group Research Poster
Computer Lab Day
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Students will create the BLAST code of their chain using the Protein BLAST coding system
handout (an example of the code is: VHLTPVEKS) and input their code into the NCBI blastp
program online. After a few seconds, the program will provide a list of top percentage protein
matches. Students should write down the top three matches that occur under the Description
and Match Score.
Students should also do a basic internet search of their amino acid sequence and attempt to
identify the matching protein. The blastp Description should provide clues in identification. For
instance, the blastp results of VHLTPVEKS describe a hemo-globin protein with a possible
mutation. Internet search of the amino acid sequence displays provides links to the disease,
sickle cell anemia.
Students should research: What type of mutation is causing the disease? Describe this type of
mutation (mismatch, point, etc.) Where does the mutation occur? What are the internal as well
as external symptoms or effects of the mutation? Without the mutation, what would the
normal protein express?
Students should include their disease and the mutation information with their Group Research
Poster. Groups should practice speaking for the presentations next class.
Assessment:
o Informal- Observation of students in computer lab as they search the database and
complete their posters.
Day 6 –
Research Poster Presentations
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Each group will give an 8-10 minute presentation of their poster. Groups should briefly discuss
the process of transcription and translation as depicted on the poster board. Groups should
focus the majority of time teaching the class about their specific disease as well as what the
mutation is, and how it occurs.
At the end of the class, we shall attempt to answer the question, why are proteins so important?
Assessment:
o Informal- Discussion on protein importance, quality of thoughts
o Formal- Presentation Rubric covering speaking quality, inclusion of each step discussed
previously, visually appealing, research regarding disease, and knowledge shared to
class on types of mutations.
Day 7–
DNA Fingerprinting Lab Begins
DNA Extraction and Electrophoresis
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As students enter the classroom, Ms. Jessica will announce new pieces of evidence are in! The
regular janitor who helps clean the science room has been out sick all last week. As she was
about to clean the room last night, she noticed there were cookie crumbs in some of the desks
and chairs around the room. Having heard about the cookie crime, she marked the location
where she found crumbs with post-it notes.
The teacher will then tell students to look under their chairs or desks and raise their hand if they
have a post-it note. Each group will have one post-it note. Students will be told that person is a
suspect in the crime and we shall use their DNA in our DNA fingerprinting forensics lab.
Each group will collect swabs from the cheek of their group suspect. They will first have to
perform the DNA Extraction Lab to burst open the cheek cells and collect the spool of human
DNA.
Ms. Jessica has already made the gels for the groups and will have them pipette their DNA
samples into the lanes. They will discuss what will happen to the DNA and gel after the
electricity is turned on. Ms. Jessica will turn on the electricity after class as it needs to run for
an hour or more. (After class, Ms. Jessica will also take the left over student samples and run a
second gel which will be used as the original DNA taking from the cookies and plate).
Assessment:
o Informal- Observation as groups work together to perform DNA extraction and begin
filling out pieces of the lab report
o Formal- Completion of activity - Each group successfully spools their DNA sample, which
can then have enzymes added and inserted in the gel lane.
Day 8 –
Suspect(s) Identification & Review of Concepts for Unit Exam
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Groups will draw the results of the gel onto their lab reports. The whole class will talk about the
predictions each group made on what would happen to the gel and DNA samples and then
discuss the results of the gel electrophoresis (enzymes added to the sample split the DNA into
fragments. Each person has their own unique band of sequences which separate across the gel
based on length of base-pairing).
Next, Ms. Jessica will bring out the original “suspect” gel she created. Groups can take turn
comparing their suspect gel to the original suspect gel. They should draw both in their reports
and identify matching band sequences between the two gels. Is there more than one? What
does this mean? While each group is taking a turn matching the two gels, the other groups
should be discussing their observations, analysis, and conclusions for the lab report write-up.
After all groups have had a chance to discuss their findings between the two gels, Ms. Jessica
will ask each group to write down who they think ate the cookies on a piece of paper. Ms.
Jessica will collect them all and read the verdicts off to the whole class. Those found guilty by
the evidence will be told to move the mock jail in the back of the class (group of desks set up in
back).
Students will be told their lab report write-ups will be due two class periods from then, and the
unit exam will be the next class. The whole class will then review together with the teacher for
the upcoming exam.
Assessment:
o Informal- Observation of each group as they work on and discuss the results of the gel
electrophoresis, as well as observation of class discussion during review.
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Formal- Each group is able to correctly identify at least one of the suspects from
matching the gels. Also, formal lab report write-ups will be turned in and graded.
Day 9 –
Formal Unit Exam
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The class will take the unit exam coving all the concepts learned thus far.
Assessment:
o Formal- Written Unit Exam, covering all concepts and labs during the unit