BAB 6 PEWARISAN SIFAT DAN BIOTEKNOLOGI Part 1 (IPA Kelas 9 Kurikulum Merdeka)

Introduction

This tutorial will guide you through the key concepts of inheritance of traits and biotechnology as discussed in the video "BAB 6 PEWARISAN SIFAT DAN BIOTEKNOLOGI Part 1." Aimed at 9th-grade students following the Merdeka curriculum, this guide covers Mendel's laws, monohybrid, and dihybrid crosses, providing a foundation for understanding genetics and its applications.

Step 1: Understanding Inheritance of Traits

Inheritance of traits is how characteristics are passed from parents to offspring. Here’s what you need to know:

• Genetics Basics

  • Traits are determined by genes, which are segments of DNA.
  • Each individual inherits one allele from each parent, resulting in a pair of alleles for each trait.

• Dominant and Recessive Traits

  • Dominant traits overshadow recessive ones. For example, if "A" is dominant and "a" is recessive, the possible combinations are:
    • AA (homozygous dominant)
    • Aa (heterozygous)
    • aa (homozygous recessive)

Step 2: Exploring Mendel's Laws

Mendel’s laws form the foundation of modern genetics. Key laws include:

• Law of Segregation

  • During gamete formation, the two alleles for a trait separate so that each gamete carries only one allele.

• Law of Independent Assortment

  • Genes for different traits are inherited independently of each other, provided the genes are located on different chromosomes.

Step 3: Conducting Monohybrid Crosses

A monohybrid cross involves one trait. Follow these steps for a basic monohybrid cross:

1. Identify Parent Genotypes

   • Example: Cross a homozygous dominant (AA) with a homozygous recessive (aa).

2. Create a Punnett Square

   • Draw a 2x2 grid.
   • Place one parent's alleles along the top and the other's along the side.

3. Fill in the Punnett Square

   • Combine the alleles to find the possible genotypes of the offspring.

4. Analyze Results

   • In the example above, all offspring will be heterozygous (Aa).

Step 4: Conducting Dihybrid Crosses

A dihybrid cross involves two traits. Here’s how to perform one:

1. Identify Parent Genotypes

   • Example: Cross a plant with the genotype AABB with one having aabb.

2. Determine Gametes

   • The first parent can produce AB and ab gametes.
   • The second parent can produce ab gametes.

3. Create a Punnett Square

   • Use a 4x4 grid, as each parent can produce two types of gametes.

4. Fill in the Punnett Square

   • Combine alleles from both parents in each box.

5. Analyze Results

   • Determine the phenotypic ratio of the offspring. In this case, you might find a 9:3:3:1 ratio.

Step 5: Applications of Biotechnology

Biotechnology leverages genetic principles for practical applications. Key areas include:

• Genetic Engineering

  • Modifying organisms to express desirable traits, such as pest resistance in crops.

• Cloning

  • Creating identical copies of organisms, used in agriculture and medicine.

• Gene Therapy

  • Introducing or altering genes within an individual's cells to treat diseases.

Conclusion

In this tutorial, we covered the basics of inheritance, Mendel's laws, monohybrid and dihybrid crosses, and the applications of biotechnology. Understanding these concepts lays the groundwork for further studies in genetics and its implications in real-world scenarios. To deepen your understanding, consider experimenting with Punnett squares using different traits or exploring advanced topics in biotechnology.