10-01-2013, 03:53 PM
The human genome (DNA) is made up of 23 billion base pairs.
It possess about 50000 – 100000 genes and is aligned as a set of 23 chromosomes.
Of the 3 billion base pairs only about 20 -30 percent are genes and related sequences whereas remaining 70- 80 percent are extragenic DNA
The gene and gene related sequence is comprised of coding (less than 10 percent) and non-coding sequence (greater than 90 percent)
The coding sequences are called as Exons.
Introns, promoters, leaders or trailers, pseudogenes and gene fragments form the non-coding sequence.
The extragenic DNA is comprised of about 20-30 percent of moderative or highly repetitive sequences and about 70 – 80 percent of unique or low copy numbers.
The repetitive sequences occur as dispersed repeats (40 percent) and clustered repeats (60 percent).
SINEs and LINEs are dispersed repetitive sequence whereas satellite DNA, mini satellite DNA and microsatellite DNA are clustered repetitive sequence.
Glossary
Exons: Coding regions of DNA
Introns: Non coding regions separating exons
Leader and Trailer sequence: These sequences being present at the 5 prime and 3 prime ends of the DNA are subjected only to transcription and restricted from being translated
Promoter sequence: Being positioned at the transcription initiation spot this sequence enables the synthesis of mRNA
Pseudogenes: Mutated form of the original gene and thus no more active participation in protein production. Pseudogenes are results of nonsense mutation
Gene Fragments: Non functional groups of fragments whose either 5 prime or 3 prime region is absent
SINE: Short Interspersed Nuclear Elements. Alu element is one of the examples for SINE
LINE: Long Interspersed Nuclear Elements. L1 LINE is one of the examples for LINE
Satellite DNA: Clusters of repetitive sequence in the human genome which is of about 100 to 5000kbp in length
Minisatellite DNA: Repetitive sequence clusters which is of about 100 base pairs to 20 kbp in length
Microsatellite DNA: Short length repetitive sequence which is less than or equal to 4 base pairs
It possess about 50000 – 100000 genes and is aligned as a set of 23 chromosomes.
Of the 3 billion base pairs only about 20 -30 percent are genes and related sequences whereas remaining 70- 80 percent are extragenic DNA
The gene and gene related sequence is comprised of coding (less than 10 percent) and non-coding sequence (greater than 90 percent)
The coding sequences are called as Exons.
Introns, promoters, leaders or trailers, pseudogenes and gene fragments form the non-coding sequence.
The extragenic DNA is comprised of about 20-30 percent of moderative or highly repetitive sequences and about 70 – 80 percent of unique or low copy numbers.
The repetitive sequences occur as dispersed repeats (40 percent) and clustered repeats (60 percent).
SINEs and LINEs are dispersed repetitive sequence whereas satellite DNA, mini satellite DNA and microsatellite DNA are clustered repetitive sequence.
Glossary
Exons: Coding regions of DNA
Introns: Non coding regions separating exons
Leader and Trailer sequence: These sequences being present at the 5 prime and 3 prime ends of the DNA are subjected only to transcription and restricted from being translated
Promoter sequence: Being positioned at the transcription initiation spot this sequence enables the synthesis of mRNA
Pseudogenes: Mutated form of the original gene and thus no more active participation in protein production. Pseudogenes are results of nonsense mutation
Gene Fragments: Non functional groups of fragments whose either 5 prime or 3 prime region is absent
SINE: Short Interspersed Nuclear Elements. Alu element is one of the examples for SINE
LINE: Long Interspersed Nuclear Elements. L1 LINE is one of the examples for LINE
Satellite DNA: Clusters of repetitive sequence in the human genome which is of about 100 to 5000kbp in length
Minisatellite DNA: Repetitive sequence clusters which is of about 100 base pairs to 20 kbp in length
Microsatellite DNA: Short length repetitive sequence which is less than or equal to 4 base pairs
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