Genetics and Inheritance

Introduction

Genetics explains how traits are inherited from one generation to the next. Understanding DNA and inheritance patterns is a key part of GCSE Biology.

This article will cover:

1. The structure and function of DNA.
2. Genetic crosses and inheritance patterns.
3. How genetic disorders arise.

1. The Structure of DNA

• DNA (Deoxyribonucleic Acid): A molecule that carries genetic information.
• Structure: A double helix with base pairs (A-T, C-G).
• Found in the nucleus, forming chromosomes.

2. Genetic Crosses and Inheritance Patterns

Key Terms

1. Alleles: Variants of a gene (dominant and recessive).
2. Genotype: Genetic makeup (e.g., BB, Bb, bb).
3. Phenotype: Observable traits (e.g., blue eyes, brown hair).

Punnett Squares

Predict inheritance patterns.
Example: Cross BB (brown) with bb (blue).

• Offspring: 100% Bb (brown).

3. Genetic Disorders

• Cystic Fibrosis: Caused by a recessive allele.
• Huntington’s Disease: Caused by a dominant allele.

Conclusion

Understanding genetics and inheritance reveals how traits are passed between generations. Practice using Punnett squares and identifying inheritance patterns to master this topic.

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