Mitochondrial DNA

It is the DNA located in the mitochondria.Mitochondrial DNA (mtDNA or mDNA) is the DNA located in the mitochondria.
They are double stranded circular DNA molecule.
It is only 16 kb in length – contains 16,600 bp.
It is haploid in nature.
It codes for 37 genes.
13 genes provide instructions for making enzymes involved in oxidative phosphorylation.
It is a process that uses oxygen and simple sugars to create ATP, the cells main energy source.

1. MITOCHONDRIAL DNA Sijo.A B.sc.Botany & Biotechnology Mar ivanios College

2. Mitochondrial DNA Mitochondrial DNA ( mtDNA or mDNA ) is the DNA located in the mitochondria. They are double stranded circular DNA molecule. It is only 16 kb in length – contains 16,600 bp . It is haploid in nature. It codes for 37 genes . 13 genes provide instructions for making enzymes involved in oxidative phosphorylation . It is a process that uses oxygen and simple sugars to create ATP , the cells main energy source.

3. Mitochondrial DNA Contains 22 tRNA and 2 rRNA coding genes. Contains only exons , no introns . D loop(D=Displacement) is a DNA triple helix where most of replication and transcription is controlled.

4. HOMOPLASMY AND HETEROPLASMY Homoplasmy : Homoplasmy is a term used in genetics to describe a eukaryotic cell whose copies of mtDNA are identical. Heteroplasmy Heteroplasmy is the presence of more than one type of mtDNA which has a mixture of both wild type and mutant DNA in a single cell. It is a rare condition and is often associated with mitochondrial DNA diiseases .

5. Maternal inheritance refers to the transmission of genes only through the female. In higher animals, mitochondrial DNA ( mtDNA ) shows maternal inheritance. During fertilisation , the sperm only contributes its nucleus( 23 chromosomes ) Mitochondria of the sperm cell are located at the mitochondrial sheath which is destroyed upon fertilization. Only available mtDNA is that of the mother’s; this is why mtDNA is of maternal origin. Maternal Inheritance of mtDNA

6. Why is mitochondrial mutation is so high? The mitochondrial genome has a very high mutation rate, 10 to 17 fold higher than that observed in nuclear DNA. It is due to insufficient DNA repair system. Lack of DNA proteins such as histones . Spontaneous error arising during DNA.

7. The diseases associated with mtDNA are: Cyclic vomiting syndrome Kearnes sayre syndrome Cytochrome c oxidase deficiency Leigh syndrome Mitochondrial complexIII deficiency

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