Inheritance Explained || How do we inherit features from our parents?

Introduction

This tutorial explains how we inherit features from our parents through genes and alleles. Understanding inheritance is essential for grasping why we resemble our parents and can also relate to genetic diseases. We will also explore cystic fibrosis as a case study of an inherited trait.

Step 1: Understand Genes and Alleles

• Definition of Genes: Genes are segments of DNA that contain the instructions for producing specific traits or characteristics.
• Definition of Alleles: Alleles are different versions of a gene. For example, a gene for eye color may have alleles for blue, brown, or green eyes.
• Inheritance of Alleles: Each parent contributes one allele for every gene. The combination of these alleles determines the traits you inherit.

Step 2: Explore Dominant and Recessive Alleles

• Dominant Alleles: If an allele is dominant, it will express its trait even if only one copy is present. For instance, if brown eyes are dominant, a person with one brown eye allele and one blue eye allele will have brown eyes.
• Recessive Alleles: Recessive alleles only express their trait if both alleles are recessive. For example, a person with two blue eye alleles will have blue eyes.
• Punnett Squares: Use a Punnett square to predict the inheritance of traits from parents. This grid helps visualize how alleles combine.

Step 3: Recognize Monohybrid Traits

• Definition of Monohybrid Traits: These traits are determined by a single gene with two alleles. For example, flower color in pea plants is a classic monohybrid trait.
• Example of Cystic Fibrosis: Cystic fibrosis is a genetic disease caused by a recessive allele. To inherit cystic fibrosis, a person must receive the recessive allele from both parents.

Step 4: Analyze Cystic Fibrosis Inheritance

• Carrier Parents: Parents who carry one recessive allele for cystic fibrosis do not show symptoms but can pass the allele to their children.
• Probability of Inheritance:
  • Two carrier parents have a:
    • 25% chance of having a child with cystic fibrosis (homozygous recessive)
    • 50% chance of having a carrier child (heterozygous)
    • 25% chance of having a child without the allele (homozygous dominant)

Conclusion

Understanding inheritance through genes and alleles is fundamental in genetics. You learned about dominant and recessive traits, monohybrid inheritance, and how genetic diseases like cystic fibrosis are passed down. To delve deeper, consider exploring genetic diagrams or genetic modification for broader applications of these concepts.