Common Dominant and Recessive Traits List for Grade 7 Biology.

📚 Understanding Dominant and Recessive Traits

In genetics, traits are characteristics that can be passed down from parents to offspring. These traits are determined by genes, which come in different versions called alleles. Dominant alleles are like the 'stronger' versions – if you have even one copy of a dominant allele, you'll show that trait. Recessive alleles, on the other hand, are 'weaker' – you need two copies of the recessive allele to show that trait. Think of it like a secret code that determines how you look and function!

🧬 History and Background

The concept of dominant and recessive traits was first introduced by Gregor Mendel in the 19th century through his experiments with pea plants. Mendel's work laid the foundation for modern genetics, showing that traits are inherited in a predictable manner. His careful observation and mathematical analysis revealed the fundamental principles of heredity.

🔑 Key Principles

• 🌱 Alleles: Different versions of a gene that determine a particular trait.
• 💪 Dominant Allele: An allele that expresses its trait even when only one copy is present.
• 🤫 Recessive Allele: An allele that only expresses its trait when two copies are present.
• 🏘️ Genotype: The genetic makeup of an individual (e.g., AA, Aa, aa).
• 👀 Phenotype: The observable characteristics of an individual (e.g., blue eyes, brown hair).
• ➕ Homozygous: Having two identical alleles for a trait (e.g., AA or aa).
• ➗ Heterozygous: Having two different alleles for a trait (e.g., Aa).

🌍 Real-World Examples

Here's a table of some common dominant and recessive traits in humans:

Example 1: Eye Color If a person has the genotype BB or Bb, they will have brown eyes because brown is dominant. Only individuals with the genotype bb will have blue eyes.

Example 2: Tongue Rolling The ability to roll your tongue is dominant. If you can roll your tongue, your genotype is either RR or Rr. If you can't, your genotype is rr.

💡 Conclusion

Understanding dominant and recessive traits is a key part of learning about genetics. By knowing which traits are dominant and which are recessive, you can predict the likelihood of certain characteristics being passed on to future generations. These principles help us understand how heredity works and how traits are expressed.