Human Mitochondrial DNA.
Composition of Mitochondrial DNA
Mitochondrial DNA, (mtDNA), is a closed circular double stranded duplex containing a
guanine-rich (H) strand and a cytosine-rich (L) strand.
In mammals mitochondrial DNA encodes :
- 13 out of 70 polypeptide units which are all vital components of the
mitochondrial respiratory chain essential for aerobic respiration . Nuclear
DNA encodes the remainder.
- 22 tRNAs and 2 rRNAs which are involved in mitochondrial protein
synthesis.
The H-strand encodes:
- 12s and 16s rRNAs
- 14 tRNAs
- 6 subunits of complex I (ND)
- 3 subunits of complex III
- 1 subunit of complex IV (COX)
- 2 subunits of complex V (ATPase)
The L-strand encodes:
Replication
The only non-coding region is the triple stranded (D) displacement-loop
produced from the additional synthesis of a piece of mitochondrial DNA, 7s DNA.
The D loop features a promoter region which sites origins of replication for
both H and L strand replication and contains elements for the initiation of
leading strand replication. The regulation of replication and transcription is
mediated by the interaction of mtDNA with nuclear encoded proteins and ribosomal
proteins.
See Also
Complex I (one)
Complex II (two)
Complex III (three)
Complex IV (four)
Complex V (five)
Complexes I to V (one to five)
mRNA
rRNA
tRNA
Date Page Updated:
25 April 2005
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