It is easier to extract blood than lung cells, and since every cell in our body has the same set of chromosomes, every cell has a complete set of genes. Explain what information we learn from genetic linkage and physical maps. Explain the role of markers in both genetic and physical maps. Explain why scientists cut up chromosomes to make maps, and why they need many copies of the chromosome. Explain why maps are important in the hunt for genes.
Genetic maps are like world maps showing landmarks without specific countries.
Physical maps of ordered markers are like maps of countries showing state outlines and a few landmarks in each state. The most detailed DNA sequence maps are like street maps, showing the location of each house or building. Starting with green on the left, red is farthest away since it is inherited with green only four times. The left section of the top line overlaps with the right section of the second line. The third line also overlaps with the right portion of the second line.