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Why This Matters for Nursing: Understanding genetics helps you explain inherited conditions to patients, identify family risk factors, and understand how genetic testing works. Many diseases have genetic components.
Genetics is the study of heredity — how traits are passed from parents to offspring through genes.
| Term | Definition |
|---|---|
| Gene | A segment of DNA that codes for a trait |
| Allele | Different versions of a gene (e.g., brown eye allele, blue eye allele) |
| Genotype | The genetic makeup (e.g., Bb) |
| Phenotype | The physical expression (e.g., brown eyes) |
| Dominant | Allele that masks another; shows even with one copy (B) |
| Recessive | Allele only shows when there are two copies (b) |
| Homozygous | Two same alleles (BB or bb) |
| Heterozygous | Two different alleles (Bb) |
Genotype = Genes you've GOT Phenotype = Physical appearance you PRESENT
Dominant = Does it (always shows) Recessive = Retreats (hides behind dominant)
Homo = Same (BB or bb) Hetero = Different (Bb)
A Punnett square predicts the probability of offspring genotypes and phenotypes.
B b
┌───────┬───────┐
B │ BB │ Bb │
├───────┼───────┤
b │ Bb │ bb │
└───────┴───────┘
Genotype ratio: 1 BB : 2 Bb : 1 bb Phenotype ratio: 3 dominant : 1 recessive (75% : 25%)
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