🧬 Genes & Chromosomes – Summary
🔹 What are Genes?
Genes are segments of DNA (Deoxyribonucleic Acid).
Each gene contains instructions to build proteins that control traits (like eye colour, height, etc.).
Humans have 20,000–25,000 genes.
Genes are inherited from parents to offspring.
➡️ Example: Gene for eye colour, blood type, or ability to roll the tongue.
🔹 What are Chromosomes?
Chromosomes are long, thread-like structures made of DNA and proteins.
Found in the nucleus of cells.
Humans have 46 chromosomes in total:
23 pairs
22 pairs are autosomes
1 pair is sex chromosomes (XX for females, XY for males)
➡️ Chromosomes carry genes. So, genes are like sentences, and chromosomes are like books that store them.
🔹 How Are They Related?
| Genes | Chromosomes |
|---|---|
| Part of DNA | Made up of DNA |
| Carry traits | Carry multiple genes |
| One gene = one instruction | One chromosome = many instructions |
🔹 Key Concepts:
Alleles: Different forms of a gene (e.g., brown vs blue eye colour)
Genotype: Genetic makeup (what genes are present)
Phenotype: Observable traits (how those genes show up)
🎯 Why Are They Important?
Genes and chromosomes determine traits, control cell function, and play a key role in heredity.
Mutations in genes or chromosomes can lead to genetic disorders.