Coding DNA sequences that encode proteins make up less than 2% of the human genome. The remaining 98% is non-coding DNA, which includes regulatory sequences, introns, repetitive elements, and other sequences not represented in proteins. While protein-coding genes have been well-studied, non-coding DNA serves numerous important functions and makes up the vast majority of the genome. Gene mapping involves assigning DNA fragments to chromosomes to create a genetic map, with the distance between genes proportional to recombination frequency.

1. The Coding and
Non-coding content of Human Genome
 Coding DNA -is defined as those sequences that can be transcribed into mRNA and translated into
proteins during the human life cycle; these sequences occupy only a small fraction of the genome
(<2%).
 Non-coding DNA -is made up of all of those sequences (ca. 98% of the genome) that are not used to
encode proteins
Coding DNA Sequence
(Protein Coding Genes)
Protein-coding sequences represent the most widely studied and best understood component of the
human genome.
These sequences ultimately lead to the production of all human proteins can lead to the production of
many more unique proteins than the number of protein-coding genes.
The complete modular protein-coding capacity of the genome is contained within the exome, and
consists of DNA sequences encoded by exons that can be translated into proteins. Because of its biological
importance, and the fact that it constitutes less than 2% of the genome, sequencing of the exome was the first
major milepost of the Human Genome Project.
Protein-coding genes are distributed unevenly across the chromosomes, with an especially high gene
density within chromosomes 19, 11, and 1 . Each chromosome contains various gene-rich and gene-poor
regions, which may be correlated with chromosome bands and GC-content. The significance of these
nonrandom patterns of gene density is not well understood.
Non- Coding DNA Sequence
Non-coding DNA is defined as all of the DNA sequences within a genome that are not found within
protein-coding exons, and so are never represented within the amino acid sequence of expressed proteins. By
this definition, more than 98% of the human genomes is comprised of ncDNA.
Numerous classes of noncoding DNA have been identified, including genes for noncoding RNA (e.g.
tRNA and rRNA), pseudogenes, introns, untranslated regions of mRNA, regulatory DNA sequences, repetitive
DNA sequences, and sequences related to mobile genetic elements.
What is Gene Mapping?
 Gene mapping, also calledgenome mapping, is the creation of a genetic map assigning DNA fragments
to chromosomes.
Genetic Mapping
The distance between genes is proportional to the frequency of recombination events.
recombination recombinant progeny

2. frequency total progeny
1% recombination = 1 map unit (m.u.)
1 map unit = 1 centimorgan (cM)
When a genome is first investigated, this map is nonexistent. The map improves with the
scientific progress and is perfect when the genomic DNA sequencing of the species has been completed.
During this process, and for the investigation of differences in strain, the fragments are identified by small tags.
When a genome is first investigated, this map is nonexistent. The map improves with the
scientific progress and is perfect when the genomic DNA sequencing of the species has been completed.
During this process, and for the investigation of differences in strain, the fragments are identified by small tags.
These may be genetic markers (PCR products) or the unique sequence-dependent pattern of DNA-
cutting enzymes. The ordering is derived from genetic observations (recombinant frequency) for these markers
or in the second case from a computational integration of the fingerprinting data. The term "mapping" is used
in two different but related context
The Purposes of Gene Mapping
 The goal is to determine the genetic components of schizophrenia and bipolar disorder
 Determine the entire nucleotide sequence of human deoxyribonucleicacid (DNA)
 It will reveal many secrets of how the human body works, and it could lead to greater disease
prevention.