How to Prepare Your BIOL 1831 SNP/RFLP Final Presentation: A Slide-by-Slide Guide
A section-by-section breakdown for BIOL 1831 lab students — covering what each of the 6 required slides must contain, how to construct slide 4’s custom RFLP diagram from your paper’s specific data, how to label your gel figure correctly, and what the rubric is actually grading in each section.
The BIOL 1831 final lab presentation is where students demonstrate they can extract the core science from a primary research article and communicate it clearly to a non-specialist audience in 5 minutes. The most common failure mode is not a lack of understanding — it is a failure to follow the rubric’s specific requirements for each slide. Students include general content when the rubric demands paper-specific content. They copy figures without labeling them correctly. Most critically, they misread slide 4 entirely and draw a generic RFLP cartoon instead of a diagram built from their own paper’s numbers. This guide explains what every slide requires, why the rubric grades it that way, and how to approach each component from scratch using your assigned journal article.
The single most misunderstood requirement in this assignment is slide 4. Your instructor explicitly noted that many draft submissions showed generic RFLP diagrams taken from other sources or drawn without reference to the paper’s data. Slide 4 must be a diagram you create, using the exact PCR product size, restriction enzyme name, cut fragment sizes, and allele associations from your specific assigned paper. A 301 bp product cut into 187 bp and 114 bp fragments by HhaI is different from every other paper’s numbers — your diagram must reflect your paper’s numbers, not a general template. No two students in the class should have an identical slide 4.
What This Guide Covers
What the Presentation Is Actually Testing
This is a science communication exercise as much as it is a genetics comprehension exercise. The rubric is testing whether you can read a primary research article about PCR-RFLP genotyping, extract the essential biological and methodological information, represent it accurately and visually, and explain it to your classmates in 5 minutes. It is not a test of memorization — you can use your slides as notes. It is a test of whether you understood your paper well enough to translate it for an audience.
The 20 points for the presentation are distributed across six slides plus visual appeal and delivery. The 5 participation points are separate and require attending every student’s presentation, not just your own. Every rubric criterion is attached to a specific, observable feature of your slides or your delivery — which means you can plan for full marks before you walk into the room.
The presentation must be submitted to Canvas before your class session. Your TA will download all files onto the classroom computer. You will not be logging in yourself or loading your file individually. This means late submissions — even by minutes — may result in your file not being available when it is your turn. Submit the night before, not the morning of.
Slide 1: Title Slide
The title slide is worth 1 point and has two specific requirements: the journal article’s full title and your name must both appear prominently on the top half of the slide, and the full citation of the article must appear in smaller text on the bottom half. This sounds straightforward, but students lose this point by using their own chosen title instead of the article’s actual title, or by formatting the citation incorrectly.
Slide 2: Gene and SNP Information
Slide 2 is worth 3 points and requires five distinct elements. Missing any one of them costs you part of this slide’s marks. Every piece of information on this slide must come from your paper — not from general genetics knowledge or from Wikipedia entries about the gene.
Name of the Gene Where the SNP Is Located (or Near)
Your paper will identify the SNP’s chromosomal location and name any nearby or associated genes. For papers using the 9p21.3 locus as an example, the nearby genes are CDKN2A and CDKN2B — but your paper’s SNP may be in or near a completely different gene. Use the gene name as given in your paper. If the SNP is intergenic (between genes), state that and identify the neighboring genes. Do not default to describing a gene you already know unless it is what your paper discusses.
SNP ID Name, Nucleotide Options, and Allele Frequencies
The SNP ID is the rs number — for example, rs4977574. State both nucleotide options at that position (e.g., A or G) and identify which is the risk allele and which is the alternative allele. Then report the allele frequencies from your paper’s study population and, if your paper reports them, from broader population databases. Frequencies should be given as percentages or proportions, not just described vaguely as “common” or “rare.”
At Least 2 Distinct Pieces of Gene Function Information as Bulleted Points
This is where students most often write vague generalities. Your paper’s introduction and discussion sections will describe the biological function of the gene associated with the SNP — what protein it encodes, what pathway it is involved in, what happens when its expression is altered. Pull two specific, distinct facts from those sections. “The gene is involved in cell regulation” is too vague. “CDKN2B encodes a cyclin-dependent kinase inhibitor that regulates the G1 phase of the cell cycle” is specific and correct. Use your paper’s language as a basis, then put it in your own words for the slide.
A Picture Representing Gene Function
This does not need to be a figure from your paper. It can be a diagram from a textbook, a figure from another educational source, or a schematic you find online — as long as it visually represents what the gene does. A cell cycle diagram works for a CDK inhibitor gene. A signaling pathway graphic works for a receptor gene. A tissue-specific expression image works for many disease-associated genes. Choose an image that a classmate with no background in this gene could look at and understand the basic function. Credit the image source in small text below it or in the slide notes.
How to Find the Required Information for Slide 2
The SNP ID, nucleotide options, and allele frequencies are almost always in the abstract and results sections of your paper. The gene name and function information are in the introduction. Re-read the introduction specifically looking for: what the gene encodes, what its normal function is, and how the SNP affects gene expression or function. The discussion section will have additional functional context. Do not rely on the abstract alone for slide 2 — the abstract typically summarizes findings, not gene biology.
Slide 3: Disease Information
Slide 3 is worth 3 points and follows a parallel structure to slide 2: name the disease, provide at least 4 distinct bulleted facts about it, and include an image. The disease is the clinical outcome that the SNP predisposes individuals to — your paper’s title and abstract will name it explicitly.
Slide 4: The Custom RFLP Diagram — The Most Misunderstood Slide
Slide 4 is worth 3 points and is the slide that most students get wrong. The instructor’s comment on the drafts was unambiguous: this must be a diagram you create, that is specific to your paper’s PCR product size, restriction enzyme, cut fragment sizes, SNP alleles, and expected heterozygote pattern. It is not a general RFLP explanation diagram, and it must not be taken or adapted from another source.
What Your Slide 4 Diagram Must Show
The rubric specifies four pieces of information that the diagram must communicate. Every one of them must be visually represented in your diagram, not just listed as bullet points alongside it.
Size of the Uncut PCR Product
Show a single DNA band or fragment representing the full PCR amplicon before restriction digestion, with its size in base pairs labeled. This number comes directly from your paper’s methods section — it is the size of the amplified genomic region. In a schematic, this is typically drawn as a horizontal line or rectangle labeled with the bp size, before an arrow showing the digestion step.
Restriction Enzyme Name and Cut Fragment Sizes
Identify the restriction enzyme used in your paper and show the two (or more) fragments produced by digestion when the risk allele is present, with each fragment’s size in bp labeled. Your paper’s results section will report these sizes explicitly. The enzyme name should appear at the cut site or in a label pointing to the digestion arrow or cut mark in your diagram.
Which Nucleotide Allele Is Uncut or Cut
Your diagram must make clear which allele (risk or non-risk; for example, G or A at a specific position) results in the restriction site being present and therefore cut, and which allele lacks the restriction site and therefore remains uncut. This is the biological core of the RFLP method — the restriction enzyme only cuts if the recognition sequence exists, and the SNP determines whether it does.
Fragment Sizes Expected if Heterozygote
A heterozygous individual carries one copy of each allele. In PCR-RFLP, this means the PCR product contains both the cuttable (risk allele) and uncuttable (non-risk allele) sequences. After restriction digestion, a heterozygous sample will show three bands: the uncut full-length product (from the non-risk allele chromosome) plus the two cut fragments (from the risk allele chromosome). Your diagram must show this explicitly — draw all three bands with their sizes labeled for the heterozygous scenario. This distinguishes your diagram from one that only shows homozygous outcomes.
How to Build the Slide 4 Diagram Step by Step
-
Locate Your Paper’s Specific Numbers
Go to your paper’s methods and results sections. Find: (1) the size in bp of the PCR amplicon — this is the “uncut PCR product” size. (2) The name of the restriction enzyme used. (3) The sizes of the fragments produced when the risk allele is present — these are the cut fragment sizes. Verify that the cut fragment sizes add up to the uncut product size (they should, minus any very small fragments that may not be visible on the gel). (4) Which nucleotide at the SNP position creates the restriction site and which does not.
-
Draw a Simple Linear Fragment Schematic
Using PowerPoint’s drawing tools, draw a horizontal rectangle or line representing the uncut PCR product. Label it with the bp size. Add a label for the allele that remains uncut (e.g., “A allele — no restriction site — uncut”). Then draw an arrow pointing downward labeled with the restriction enzyme name. Below the arrow, draw two shorter rectangles representing the cut fragments, each labeled with their bp sizes. Label these as associated with the risk allele (e.g., “G allele — GCGC site present — cut by HhaI”). You do not need artistic skill — a clear, labeled schematic drawn in PowerPoint shapes is exactly what is required.
-
Add the Heterozygote Panel
Create a third column or section of your diagram showing the heterozygous result. Draw three bands: the full-length uncut product at the top, and the two cut fragments below it. Label all three with their sizes. Add a label identifying this as the heterozygote (G/A) pattern. This makes clear that your diagram covers all three possible genotypes: homozygous risk (GG), homozygous non-risk (AA), and heterozygous (GA or AG).
-
Organize It as a Genotype Comparison Table or Panel
A clean approach is to present three side-by-side panels, each showing the expected band pattern for one genotype. Label each panel with its genotype (e.g., AA, GG, GA). This mirrors how gel results are actually interpreted — each lane of a gel corresponds to one patient sample, and its band pattern identifies the genotype. This structure makes the diagram immediately useful for understanding slide 5’s gel figure as well.
-
Add a Slide Title That Contextualizes the Diagram
The slide title should not just say “RFLP Diagram.” It should be informative: something like “PCR-RFLP for rs4977574: HhaI Digestion Patterns by Genotype” or “How HhaI Cuts the 301 bp PCR Product at the G Risk Allele.” A title that describes what the diagram shows helps the audience orient before they look at the figure itself.
What Slide 4 Must NOT Be
A general diagram of how restriction enzymes work taken from a textbook or website. A diagram that shows abstract DNA bands without specific bp sizes. A figure from your paper (the gel figure belongs on slide 5, not slide 4). A diagram that only shows one genotype outcome. A diagram from another student’s presentation or from a previous year’s class. Any of these errors means the 3 points for slide 4 are not earned.
What Slide 4 Should Be
A diagram you drew yourself in PowerPoint (or any drawing tool) using the exact numbers from your assigned paper. It should show: the uncut PCR product with its bp size labeled, the restriction enzyme name, the cut fragments with their bp sizes labeled, which allele each pattern corresponds to, and the heterozygote pattern showing all three bands. It is specific, numbered, and unique to your paper.
Slide 5: Gel Figure Analysis
Slide 5 is worth 3 points and requires you to take a gel electrophoresis figure directly from your paper and present it with correct, informative labels and clear interpretation. There are two components: accurate labeling of the gel image itself, and written conclusions drawn from the data.
How to Label the Gel Figure Correctly
The gel figure from your paper will show multiple lanes. Some lanes contain PCR products without restriction enzyme digestion (negative controls or pre-digestion). Some lanes contain digested samples. A DNA size ladder (marker) will appear in one or more lanes. Your job is to annotate every lane with an informative genotype label, and annotate every visible band with a meaningful identification.
Writing the 2–3 Bullet Point Conclusions
Below or alongside the labeled gel figure, the rubric requires 2–3 brief bulleted points explaining the main conclusions from the gel data. These are not descriptions of the method — they are interpretations of the results. The distinction matters for the grade.
Description (Not What Is Required)
“The gel shows bands at 301 bp in some lanes and at 187 bp and 114 bp in other lanes. The marker is in lane M.”
This describes what is visible but draws no conclusions. A conclusion requires interpretation: what does the band pattern tell you about the patient’s genotype, and what does the genotype tell you about disease risk?
Conclusion (What Is Required)
- “Samples showing only a 301 bp band are homozygous non-risk (AA) — no restriction site present.”
- “Samples showing 187 bp and 114 bp bands are homozygous risk (GG) — complete digestion confirms both alleles carry the SNP.”
- “Samples showing all three bands are heterozygous (GA) — partial digestion indicates one risk and one non-risk allele.”
How to Write Conclusions That Earn Full Marks on Slide 5
Each bullet should contain three components: what the band pattern looks like, what genotype that pattern corresponds to, and what that genotype implies for the individual’s disease risk or for the study’s findings. One bullet per genotype type works well. If your paper’s gel shows something beyond the basic genotype patterns — such as non-specific bands, partial digestion, or a particularly interesting sample distribution between patients and controls — include a fourth bullet noting that observation and its significance.
Slide 6: Significance and Benefits
Slide 6 is worth 2 points and asks you to explain the benefits of obtaining data about this SNP using the RFLP method and what the data implies for disease diagnosis. This slide synthesizes everything from slides 2–5 into a “so what?” argument. It should not be a general statement about why genetics is useful.
Benefits of the PCR-RFLP Method Specifically
PCR-RFLP is used instead of more expensive high-throughput SNP arrays for a reason. Explain that reason: it is cost-effective, accessible to smaller clinical and research labs, uses standard equipment, and provides clear, interpretable results without requiring specialized sequencing infrastructure. Your paper’s discussion section will likely make this argument — summarize it in 2–3 concise points specific to your paper’s context.
Implications for Disease Diagnosis
What does knowing a patient’s genotype for this SNP actually mean clinically? Does it identify elevated risk for early-onset disease? Does it stratify patients into risk categories that affect treatment decisions? Does it enable population screening or family risk assessment? Draw directly from your paper’s conclusion and discussion — these sections typically address clinical implications explicitly. Make the connection between “this SNP increases MI risk by X%” and “therefore genotyping for this SNP could inform preventive care.”
Contribution to the Research Field
If your paper is the first to develop a PCR-RFLP method for this particular SNP (as is the case for some assigned papers), that novelty is itself significant — it creates a tool other researchers can use. If your paper extends previous work to a new population, explain why population-specific allele frequency data matters: different populations have different baseline risk frequencies, which affects how the SNP should be interpreted in clinical settings for those groups.
Visual Appeal: Font Size, Layout, and Information Density
Visual appeal is worth 2 points and is graded on three observable criteria: organization, font size, and succinctness. None of these require design expertise — they require deliberate choices about what to put on each slide and how large to make it.
Delivery: Timing, Eye Contact, and Pointing at the Screen
Presentation skills are worth 3 points and are graded on four specific observable behaviors: voice projection, eye contact, pointing at figures and diagrams to orient the audience, and staying within the 4.5–5.5 minute window. All four are practiceble and predictable — none of them require natural charisma.
Voice Projection
The grader is listening to whether your voice reaches the back of the room, not whether it is a perfect broadcast voice. Speak louder than feels natural — presentation rooms amplify the sense that you are too loud, but to the audience at the back you are usually still too quiet. Practice by speaking at your bedroom wall from across the room. If you cannot hear yourself clearly at 10 feet, project more. Avoid dropping your volume at the end of sentences — that is the most common projection failure.
Eye Contact
Look at the audience, not at your slides. Your slides are behind you or beside you — glancing at them occasionally to orient is fine, but sustained back-turning or reading from the screen loses marks. The practical technique: know your slide content well enough that a glance at the title or first bullet is enough to trigger your verbal explanation. Practice your presentation twice with the slides, then once facing away from them to confirm you know the content without reading it.
Pointing at Figures and Diagrams
The rubric specifically lists “points directly to screen to show audience particular parts of figures, diagrams, etc.” as a graded behavior. When you are discussing slide 4’s diagram, physically walk to the screen and point to the specific band, cut site, or fragment you are discussing. When discussing slide 5’s gel, point to the specific lane or band. This behavior directs the audience’s attention and demonstrates you understand which part of the visual is relevant at each moment of your explanation.
Timing: 4.5–5.5 Minutes
Full credit for timing requires staying between 4.5 and 5.5 minutes. Presentations under 4.5 minutes suggest you omitted required content or did not develop your explanations. Presentations over 5.5 minutes suggest poor preparation and may disrupt the class schedule. Time yourself with your actual slides. Most students who run over time have too much text on their slides and are reading it aloud — if you can say each slide’s key points in 45–60 seconds, a 6-slide presentation fits in 4.5–6 minutes. Practice at least twice with a timer.
Understanding PCR-RFLP Well Enough to Present It
You do not need to be an expert in molecular biology to present this topic, but you do need to be able to explain the logic of the PCR-RFLP method in plain terms. If an audience member asks you “why does cutting the DNA tell you what allele someone has?” you need to have an answer. Here is the conceptual framework you need to internalize before your presentation.
The Logic of PCR-RFLP in Plain Language
PCR-RFLP works because restriction enzymes cut DNA only at specific nucleotide sequences. If a SNP changes one nucleotide at a position that is part of a restriction enzyme’s recognition sequence, the enzyme will cut DNA from individuals carrying that variant but will NOT cut DNA from individuals carrying the original sequence at that position.
The process has three steps. First, PCR amplifies a specific genomic region from the patient’s DNA — the region that contains the SNP. Every patient’s PCR produces a fragment of the same size from both copies of their genome. Second, the restriction enzyme is added to the PCR product. If the patient has the SNP risk allele on a chromosome, the enzyme cuts that copy. If they do not have it, that copy is uncut. Third, gel electrophoresis separates the fragments by size. The pattern of bands reveals the genotype:
- One band at the full PCR product size — patient has no copies of the risk allele (homozygous non-risk, AA)
- Two bands at the smaller cut fragment sizes — patient has two copies of the risk allele (homozygous risk, GG)
- Three bands — patient has one of each (heterozygous, GA) — one chromosome is cut, one is not
This method is valuable because it requires only standard PCR and gel electrophoresis equipment — both of which are available in any molecular biology lab — rather than expensive SNP microarrays or sequencing platforms. It can identify individual patients’ genotypes for a specific SNP quickly and cost-effectively.
For a peer-reviewed foundation on PCR-RFLP as a genotyping tool, see: Fan, J.B., Chee, M.S. & Gunderson, K.L. (2006). Highly parallel genomic assays. Nature Reviews Genetics, 7, 632–644. This review article explains the range of methods used for SNP genotyping, including PCR-RFLP, and contextualizes its cost-effectiveness advantages relative to high-throughput platforms. It is directly cited in several papers that use PCR-RFLP methods for SNP analysis and is an appropriate source to understand why this methodology was chosen in your assigned paper. Available through most university library databases.
How to Read Your Assigned Journal Article for This Presentation
Many students find primary research articles difficult to read because they try to read them the way they read a textbook — linearly, every word. For a presentation, you need targeted extraction of specific information. The following reading strategy maps each section of a typical PCR-RFLP research article to the slide it informs.
| Paper Section | Read It For | Informs Slide(s) |
|---|---|---|
| Abstract | SNP ID, disease name, method overview, key findings (allele frequencies in patients vs. controls) | Slides 1, 2, 3, 6 |
| Introduction | Gene function, SNP’s biological mechanism, disease background, why this SNP is significant, why PCR-RFLP was chosen | Slides 2, 3, 6 |
| Methods – Study Population | Number of patients and controls, inclusion criteria, demographics | Slide 3 (background), Slide 6 |
| Methods – PCR | PCR product size (bp), primer sequences (you do not need to present these), PCR conditions | Slide 4 |
| Methods – RFLP | Restriction enzyme name, digestion conditions, fragment sizes produced, gel conditions | Slide 4, Slide 5 |
| Results – Gel Figures | The actual gel image for slide 5; band pattern descriptions; genotype distribution table | Slide 5 |
| Results – Statistics | Allele frequencies in patients vs. controls, p-value for significance, frequency comparisons to other populations | Slides 2, 6 |
| Discussion & Conclusion | Interpretation of frequency differences, clinical implications, limitations, future directions, significance of the PCR-RFLP method development | Slide 6 |
The Most Efficient Way to Extract Information for Each Slide
Read the abstract first to get the overall picture. Then go directly to the methods section and extract the four specific numbers you need for slide 4: PCR product size, enzyme name, and cut fragment sizes. Then go to the introduction and mark two facts about gene function and four facts about the disease for slides 2 and 3. Then return to the results section and examine the gel figure you will use for slide 5, noting which lanes correspond to which genotypes. Finally, read the discussion and conclusion for the significance content of slide 6. You do not need to understand every technical detail of the methods section — you need to understand the logic of the method and the specific numbers your paper reports.
Where Most Presentations Lose Points
Generic Slide 4 Diagram
Drawing a diagram from a textbook or online source that shows how RFLP works in general, without using your paper’s specific bp sizes, enzyme, or allele information. This earns 0 points on slide 4 regardless of how well-drawn it is. The rubric is grading paper-specific content, not generic understanding of the method.
Instead
Open your paper to the methods and results sections. Find the PCR product size, the enzyme name, and the cut fragment sizes. Draw a PowerPoint schematic from those numbers. Label every element. Add the heterozygote panel. This takes 20–30 minutes and is worth 3 points.
Gel Figure Without Labels or With Paper’s Legend
Copying the gel figure from the paper and pasting it onto the slide without adding any annotations, or pasting the paper’s figure legend below it. An unlabeled gel is uninterpretable to an audience watching a 5-minute presentation. The paper’s legend is written for journal readers, not for live audiences.
Instead
Use PowerPoint’s text box and arrow tools to add genotype labels above or below each lane, size labels beside each band, and identification labels (uncut product, cut at SNP, marker) pointing to each band type. Then write 2–3 bullets below the figure that state what the gel results mean for genotype and risk allele frequency distribution.
Only 3 Disease Facts on Slide 3
The rubric requires at least 4 distinct bulleted facts about the disease. Students who read the paper quickly often extract only 2–3 pieces of information about the disease and then run out of ideas. This is a rubric compliance error, not a comprehension error — the information is in the paper’s introduction, it just requires careful reading to extract four distinct facts.
Instead
Re-read the introduction of your paper specifically looking for: prevalence (how many people affected globally or in a specific population), age of onset or demographic patterns, key risk factors or causes, primary physiological mechanism or symptoms, and any statistics about mortality or morbidity. These five categories will yield well more than four distinct facts in almost any paper’s introduction.
Running Over or Under the Time Limit
A presentation shorter than 4.5 minutes suggests incomplete coverage of the required content. A presentation longer than 5.5 minutes means either too much content on the slides, reading slides word-for-word, or insufficient rehearsal. Both extremes lose the timing component of the 3 presentation skills points.
Instead
Time yourself with your completed slides at least twice before the presentation day. Aim for 45–50 seconds per slide across 6 slides, giving you 4.5–5 minutes. If you are running over, identify which slide you spend the most time on and reduce the bullet content so you can say each point in fewer words. If you are running under, add a brief transition sentence between slides to build continuity.
- Slide 1: Article title and your name on top half; full citation in smaller text on bottom half
- Slide 2: Gene name, SNP rs ID, both nucleotide options and allele frequencies, 2+ gene function bullets from your paper, image with source credit
- Slide 3: Disease name, at least 4 distinct factual bullets from your paper’s introduction, image with source credit
- Slide 4: A diagram YOU made with your paper’s specific PCR product size, enzyme name, cut fragment sizes, allele-to-cut or uncut association, and the heterozygote 3-band pattern — all labeled with bp sizes
- Slide 5: Gel figure from your paper with each lane labeled by genotype, each band labeled as uncut PCR product or cut fragment with sizes, no paper legend, and 2–3 bullets stating conclusions from the gel data
- Slide 6: Specific benefits of PCR-RFLP for this SNP and specific clinical implications of knowing patients’ genotypes for this SNP and disease
- All text is at least 24pt and readable from the back of a classroom
- Each bullet is a phrase or brief sentence, not a paragraph
- Presentation has been timed at 4.5–5.5 minutes with slides
- File uploaded to Canvas before class start time