BIOLOGI SMA Kelas 12 - Pewarisan Sifat PART 2 (Penyimpangan Semu Hukum Mendel) | GIA Academy

Introduction

This tutorial focuses on the concepts of deviations from Mendel's laws of inheritance as discussed in the video. We will explore key genetic principles such as epistasis, hypostasis, cryptomery, polymerism, complementary genes, and atavism. Understanding these concepts is essential for mastering genetics, especially for students in high school biology.

Step 1: Understand Epistasis and Hypostasis

• Epistasis refers to the interaction between genes where one gene suppresses or masks the expression of another.
• Hypostasis is the gene that is masked by the epistatic gene.
• Practical Example: In coat color of Labrador retrievers, the presence of the dominant allele for black (B) can be masked by the recessive allele for yellow (ee).

Step 2: Learn About Cryptomery

• Cryptomery occurs when the effects of a gene are not expressed unless combined with another specific gene.
• This interaction can lead to unexpected phenotypes.
• Practical Example: In certain plants, one gene may not express its trait unless another gene that influences its expression is also present.

Step 3: Explore Polymerism

• Polymerism is when multiple genes contribute to a single trait, resulting in a range of phenotypes.
• Traits such as skin color and height in humans are often polygenic.
• Tip: Recognize that polygenic traits typically exhibit continuous variation.

Step 4: Investigate Complementary Genes

• Complementary genes are pairs of genes that work together to produce a particular phenotype.
• When one gene is absent, it can prevent the expression of the other gene.
• Example: In sweet peas, two genes are required for the expression of purple flower color; if either is absent, the flowers will be white.

Step 5: Understand Atavism

• Atavism is the reappearance of an ancestral trait in an organism that typically does not express it.
• This phenomenon can be a result of genetic mutations or changes in gene expression.
• Common Pitfall: Do not confuse atavism with normal variation; it specifically refers to traits that are rarely expressed.

Step 6: Review Sample Problems

• Practicing sample problems can help solidify your understanding of these concepts.
• Work through problems that require you to identify types of genetic interactions and predict phenotypes based on given genotypes.

Conclusion

Understanding deviations from Mendel's laws enhances your grasp of genetics. Key concepts include epistasis, hypostasis, cryptomery, polymerism, complementary genes, and atavism. To further your learning, consider reviewing these concepts through practical examples and sample problems. Engaging with real-world applications will deepen your comprehension and prepare you for more advanced topics in genetics.