Contextualization

Genetics is the branch of Biology that studies heredity, that is, the process of transmitting physical and biological characteristics from parents to offspring over generations. At the heart of this study are the discoveries of Gregor Johann Mendel, an Austrian monk who is often referred to as the 'father of modern genetics'. In particular, Mendel's First Law - also known as the Law of Segregation - is a fundamental principle that we need to understand in order to unravel the mysteries of heredity.

Mendel's First Law describes how alleles - variations of a gene - are separated and distributed to offspring. In other words, this law states that each offspring will receive one allele from each parent, without mixing. This simple principle has huge implications for how characteristics are transmitted from generation to generation.

This law is of vital importance in various fields of knowledge. From agriculture to medicine, Mendel's First Law helps in understanding how characteristics are passed on, aiding in the development of more resilient and productive crops, as well as in predicting genetic diseases in humans.

In agriculture, for example, understanding this law helps in the development of stronger crops, allowing farmers to select seeds with desirable traits for planting in the next season. In medicine, understanding genetic inheritance through Mendel's First Law is crucial to predicting the likelihood of an individual inheriting a genetic disease.

Practical Activity

Activity Title: 'Simulating Mendel's First Law: Dominant x Recessive'

Project Objective

The objective of this project is to carry out a practical simulation to understand Mendel's First Law. Through this activity, students should be able to understand how alleles are segregated and distributed to offspring and the difference between dominant and recessive genes. In addition, students will also learn how to calculate the probabilities of a specific child of parents with a pair of specific alleles being born with dominant or recessive traits.

Detailed Project Description

This project will be carried out in groups of 3 to 5 students. Each group will simulate the crossing of peas, as Gregor Mendel did in his studies, using coins to represent the alleles. The activity will be divided into two parts: the simulation of allele segregation and the analysis of the results.

Required Materials

• Two coins per group.
• A large board or a piece of paper to record the results of the coin tosses.
• Pen or marker.

Detailed Step-by-Step for Carrying Out the Activity

Part 1: The simulation

1. Each coin represents an allele. Determine that one side of the coin represents the dominant allele ('A') and the other side represents the recessive allele ('a').
2. Each pair of coins represents an organism. Decide together which organisms you will cross. For example, you can choose to cross an organism AA with an organism aa.
3. Toss the coins and record the result.
4. Repeat the coin toss 50 times to simulate the crossing of various organisms.

Part 2: Analysis of the results

1. Calculate the frequency of each allele combination (AA, Aa, aa) resulting from the crosses. This is done by dividing the number of times each combination occurred by the total number of tosses (50).
2. Now, calculate the theoretical probability of each of these combinations occurring in the crossing of the organisms you chose at the beginning.
3. Compare the observed frequencies with the theoretical probabilities. Are they equal? If not, why do you think this happened?

Project Delivery and Connection with Activities

After carrying out the practical activity, each group must prepare a written report containing:

• Introduction: Provide context on Mendel's First Law, its relevance, real-world applications, and the objective of this project. Include the description of the organisms you chose to cross and why.

• Development: Describe in detail the activity you carried out. Include an explanation of the theory behind Mendel's First Law and allele segregation, a description of the step-by-step of the simulation, the methodology used to calculate the observed frequencies and theoretical probabilities, and the presentation and discussion of the results obtained.

• Conclusion: Draw conclusions by summarizing the main points of the report, explaining the learnings obtained and the conclusions drawn about the project. If the observed frequencies and theoretical probabilities were not equal, explain why you think this happened and what this tells us about Mendel's First Law and the real world.

• Bibliography: Cite the sources you relied on to work on the project. These sources can be books, web pages, videos, etc.

The report must be submitted to the teacher on a previously established date.