Gene mapping involves three main steps: 1) dividing chromosomes into smaller fragments that can be characterized and propagated, 2) ordering the fragments to correspond to their locations on chromosomes, and 3) determining the base sequence of each fragment. Gene maps describe the order and spacing of genes or markers on each chromosome. There are two main types of maps - genetic linkage maps that show relative locations of DNA markers, and physical maps including low-resolution maps assigning genes to chromosomes and high-resolution maps ordering restriction enzyme fragments at the DNA level. Maps are valuable for locating disease genes and enabling studies of human biology and disease.

1. Gene Mapping By: Lauren Mary

2. Process of Gene Mapping 1) Dividing the chromosomes into smaller fragments that can be propagated and characterized 2) Ordering (mapping) them to correspond to their respective locations on the chromosomes. 3) Determine the base sequence of each of the ordered DNA fragments. http://www.dnalc.org/view/15477-The-public-Human-Genome-Project-mapping-the-genome-sequencing-and-reassembly-3D-animation-.htm

3. Gene Maps = Describes the order of genes or other markers and the spacing between them on each chromosome. http://www.dnalc.org/view/16812-Animation-39-A-genome-is-an-entire-set-of-genes-.html

4. Types of Maps Genetic Linkage Maps Physical Maps Low Resolution Chromosomal map cDNA Map High Resolution Macrorestriction maps : Top-down mapping Contig Maps: Bottom-up mapping

5. Genetic Linkage Maps Shows the relative locations of specific DNA markers along the chromosome

6. Physical Maps Low-Resolution maps: Chromosomal map : Genes or other identifiable DNA fragments are assigned to their respective chromosomes, with distances measured in base pairs cDNA map : shows the positions of expressed DNA regions relative to particular chromosomal regions or bands. Can provide the chromosomal location for genes whose functions are currently unknown For disease-gene hunters, the map can suggest a set of candidate genes to test when the approximate location of a disease gene has been mapped by genetic linkage

7. Physical Maps High-Resolution maps: Macrorestriction maps : Top-down mapping : a single chromosome is cut into lg. pieces, which are ordered and subdivided ; the smaller pieces are mapped further. Resulting in the depiction of the order and distance between sites at which rare-cutter enzymes cleave. Contig maps: Bottom-up mapping : an approach involving cutting the chromosome into small pieces, each of which is cloned and ordered Resulting with the ordered fragments forming contiguous DNA blocks.

8. Value of Maps Genetics maps: Can locate the exact location of several important disease genes . i.e. cystic fibrosis, sickle cell , Tay-Sachs disease, and fragile X syndrome . Physical Maps: will eventually be used to analyze physical traits associated with chromosomal abnormalities A completed map will provide biologists with a “Rosetta Stone” for studying human biology A completed map will also enable medial researches to begin to unravel the mechanisms of inherited diseases.

9. Disadvantages Will require substantial improvements in the rate, efficiency , and reliability of standard sequencing procedures. Hard to correlate mapping data from different laboratories b/c of differences in generating, isolating, and mapping DNA fragments.

10. Goals of Gene Mapping Finding all of the genes in the DNA sequence and to develop tools for using this info. in the study of human biology and medicine. To make a series of descriptive diagrams/maps of each human chromosome at increasingly finer resolutions.