its about transposable elements in humans LINES and SINES.

1. TRANSPOSABLE ELEMENTS IN
HUMANS
• Transposon, class of genetic elements that can “jump” to
different locations within a genome.
• These elements are frequently called “jumping genes,” they
are always maintained in an integrated site in the genome.
• Most transposons eventually become inactive and no
longer move.
• Transposons were first discovered in corn (maize) by
American scientist Barbara McClintock.

2. • About 45% of the human genome consists of sequences
derived from transposable elements.
• Comparison of human and chimpanzee genomes suggests
that almost 11,000 transposition events have taken place
since these two species diverged.
• Most common transposable elements in the human
genome is Alu.

3. Two types of transposons present in human
genome
1. LINEs (Long Interspersed Nuclear Elements)
2. SINEs (Short Interspersed Nuclear Elements)

4. LINEs
• LINEs are the most abundant transposable element within
the human genome, with approximately 20.7% of the
sequences identified as being derived from LINEs.
• Group of non-LTR (long terminal repeat) retrotransposons
that are widespread in the genome of many eukaryotes.
• The only active lineage of LINE found within humans
belongs to the LINE-1 class, and is referred to as L1Hs.

5. • Autonomous elements with their own machinery for
movement.
• Most LINEs in the human genome have been shortened at
the 5′ end.
• Longest LINEs are usually about 6000 bp but, because most
copies are shortened, the average LINE is only about 900 bp.
• There are approximately 900,000 copies of LINEs in the
human genome.

6. SINEs
• SINEs are classified as non-LTR retrotransposons because
they do not contain long terminal repeats (LTRs).
• Alu elements are most common SINEs and constitute about
11% of the human genome.
• Most SINEs are copies of transposable elements that have
been shortened at the 5′end.

7. • Because the reverse-transcription process used in their
transposition terminated before the entire sequence was
copied.
• SINEs are non-autonomous elements, depend upon enzyme
coded by LINEs for their transposition.
• SINEs have been identified as the cause of mutations in
more than 20 cases of human genetic disease.