Genetics - Lab Exercise

**LAB EXERCISE TITLE:** Understanding Genetic Disorders through PCR and DNA Analysis

**LAB INFORMATION:**

* Duration: 2-3 hours
* Group size: 4-6 students
* Difficulty level: STEP1 (Foundational)

This laboratory exercise aims to introduce students to the principles of genetic disorders, PCR (Polymerase Chain Reaction), and DNA analysis. Students will learn to perform a PCR reaction, extract DNA from blood samples, and analyze their results using gel electrophoresis.

**LEARNING OBJECTIVES:**

1. Perform a PCR reaction for specific genetic markers
2. Extract DNA from human blood samples
3. Analyze DNA samples using gel electrophoresis
4. Interpret PCR results in the context of genetic disorders
5. Understand the clinical relevance of genetic testing and its applications

**BACKGROUND & THEORY:**

Genetic disorders are caused by mutations in specific genes that can lead to a range of diseases, from mild to severe. PCR is a technique used to amplify specific DNA sequences, allowing for the detection of genetic mutations. Gel electrophoresis is used to separate and analyze the DNA molecules.

This lab exercise is important clinically as it provides students with hands-on experience in performing genetic testing procedures that are commonly used in medical diagnostics. By understanding how to perform PCR and DNA analysis, students will gain insight into the complexities of genetic disorders and their implications for patient care.

**EXPECTED OUTCOMES:**

* Students will be able to perform a PCR reaction for specific genetic markers
* Students will be able to extract DNA from human blood samples
* Students will be able to analyze DNA samples using gel electrophoresis
* Students will be able to interpret PCR results in the context of genetic disorders

**MATERIALS & EQUIPMENT:**

* PCR kits (including primers, dNTPs, and buffer)
* DNA extraction kit (including phenol-chloroform solution and proteinase K)
* Gel electrophoresis equipment (including power supply, gel plates, and combs)
* Safety equipment (including gloves, goggles, and lab coats)
* Blood samples (from a volunteer or synthetic source)
* DNA markers (e.g. 100 bp ladder)
* PCR software (optional)

**PROCEDURE / PROTOCOL:**

1. **Preparation** (10 minutes)
* Set up the PCR equipment and prepare the reagents
* Ensure all necessary safety equipment is available
2. **DNA Extraction** (20 minutes)
* Extract DNA from blood samples using the phenol-chloroform solution
* Purify the DNA using proteinase K and ethanol
3. **PCR Reaction** (40 minutes)
* Prepare the PCR reaction mixture according to the kit instructions
* Perform the PCR reaction using a thermocycler or microwave
4. **Gel Electrophoresis** (30 minutes)
* Load the PCR products onto a gel plate
* Run the gel electrophoresis using a power supply and combs
5. **Data Analysis** (20 minutes)
* Visualize the gel electrophoresis results using a UV transilluminator or chemiluminescent detection system
* Analyze the PCR products using PCR software (if available)

**DATA COLLECTION & ANALYSIS:**

* Record the following data:
+ PCR reaction parameters (temperature, time, and cycling number)
+ DNA extraction yield and purity
+ Gel electrophoresis results (size and intensity of PCR products)
* Use a data table or form to record the data

**CLINICAL CORRELATIONS:**

* Genetic disorders can be caused by mutations in specific genes that affect protein function or structure
* PCR is used to detect genetic mutations that may lead to disease
* Gel electrophoresis is used to visualize and analyze DNA molecules

Common errors:

* Incorrect primer design or annealing temperature
* Inadequate DNA extraction or purification
* Insufficient PCR reaction time or temperature
* Incorrect gel electrophoresis conditions (e.g. voltage, current)

**POST-LAB QUESTIONS:**

1. What are the clinical applications of genetic testing?
2. How does PCR work and why is it useful for detecting genetic mutations?
3. What are some common genetic disorders associated with specific gene mutations?
4. How can gel electrophoresis be used to analyze DNA molecules?
5. What safety precautions should be taken when performing PCR reactions?

**ASSESSMENT CRITERIA:**

* Checklist of skills demonstrated (PCR reaction, DNA extraction, gel electrophoresis)
* Grading rubric based on data quality and completeness
* Common mistakes to watch for during the lab exercise

**REFERENCES & RESOURCES:**

* Guidelines for genetic testing and PCR procedures
* Video demonstrations of PCR and gel electrophoresis techniques
* Further reading on genetic disorders and their applications in medicine