gen-define-linkage-and-recombination-and-give-one-short-worked-e-c5eb

Define linkage and recombination and give one short worked example.

# Linkage and Recombination ## Definitions **Linkage**: The tendency of genes located on the same chromosome to be inherited together because they don't assort independently during meiosis. **Recombination**: The process by which chromosomes exchange segments during meiosis (crossing over), producing offspring with gene combinations different from either parent. Recombination frequency indicates the distance between genes. ## Worked Example **Cross**: A dihybrid test cross in *Drosophila* - Genes: body color (B = gray, b = black) and wing size (V = normal, v = vestigial) - Parent 1: BbVv (gray body, normal wings) - Parent 2: bbvv (black body, vestigial wings) **Results**: - Gray body, normal wings (BbVv): 965 - Black body, vestigial wings (bbvv): 944 - Gray body, vestigial wings (Bbvv): 206 - Black body, normal wings (bbVv): 185 **Analysis**: - **Parental types** (most frequent): 965 + 944 = 1,909 - **Recombinant types** (least frequent): 206 + 185 = 391 - **Total offspring**: 2,300 **Recombination frequency** = (391/2,300) × 100 = **17%** **Conclusion**: The genes are **linked** (on the same chromosome) but are **17 map units apart**, allowing some recombination through crossing over.