An Introduction

Q. What does DNA stand for ?

A. DNA is deoxyribosenucleic acid.
Pronounced :- 'd - oxy - rye - bose - new - clay - ic - acid'

Q. What is DNA ?

A. DNA has been called 'the genetic code of life'.
It has the form of a 'double helix'- which is a shape like a ladder, but with a gentle twist.

Q. What are 'bases ?

The rungs of the helix, or ladder, are made up of pairs of simple chemicals, or 'bases',
together with molecules of ribose, a sugar.
There are only 4 bases - 'adenine, cytosine, guanine, thymine'
- which for simplicity are called 'A', 'C', 'G' & 'T'.
And, 'A' always forms a 'base pair' with 'T', and 'C' a 'base pair' with 'G'.
Note: lower case letters 'a', 't', 'c' & 'g' are often used instead of capitals.

Q. What are 'Mitochondria' ?

A. Most cells of the human body have a single nucleus and many small 'organelles' called 'mitochondria'.
There may be several hundreds of mitochondria in a cell.

Q. What are 'Mitochondria' for ?

A. Mitochondria are described as being 'power stations' for a cell
as they are structures in which energy is produced and stored.

Q. What is 'Mitochondrial DNA' ?

A. This the small amount of DNA found in each mitochondrion.

Q. What is the structure of 'Mitochondrial DNA' ?

A. The DNA in a mitochondria is 'circular'
- unlike the DNA in the chromosomes of the nucleus which is in long strands.

Q. What are the functions of mitochondial DNA ?

A. Human Mitochondrial DNA contains:-

13 genes coding for proteins.
All are involved in energy transfer processes within the cell. NADH dehydrogenase subunit 1 (ND1) NADH dehydrogenase subunit 2 (ND2) NADH dehydrogenase subunit 3 (ND3) NADH dehydrogenase subunit 4L (ND4L) NADH dehydrogenase subunit 4 (ND4) NADH dehydrogenase subunit 5 (ND5) NADH dehydrogenase subunit 6 (ND6) cytochrome c oxidase subunit I (COX1) cytochrome c oxidase subunit II (COX2) cytochrome c oxidase III (COX3) ATP synthase F0 subunit 6 (ATP6) ATP synthase F0 subunit 8 (ATP8) cytochrome b (CYTB) 2 genes to produce ribosomal proteins. 12S ribosomal RNA 16S ribosomal RNA And, 22 transfer RNA genes. Each relating to a specific amino acid. (There are 2 for some acids.) tRNA-Phe .. Phenylalanine .. F tRNA-Val .. Valine .. V tRNA-Leu .. Leucine .. L tRNA-Ile .. Isoleucine .. I tRNA-Gln .. Glutamine .. Q tRNA-Met .. Methionine .. M tRNA-Trp .. Tryptophan .. W tRNA-Ala .. Alanine .. A tRNA-Asn .. Asparagine .. N tRNA-Cys .. Cysteine .. C tRNA-Tyr .. Tyrosine .. Y tRNA-Ser .. Serine .. S tRNA-Asp .. Aspartic Acid .. D tRNA-Lys .. Lysine .. K tRNA-Gly .. Glycine .. G tRNA-Arg .. Arginine .. R tRNA-His .. Histidine .. H tRNA-Ser .. Serine .. S tRNA-Leu .. Leucine .. L tRNA-Glu .. Glutamic acid .. E tRNA-Thr .. Threonine .. T tRNA-Pro .. Proline .. P There are also 2 hypervariable regions HVR-I and HVR-II. These areas do not appear to have any obvious function, but their presence does make the mitochondrial DNA a certain size which may be important for the correct functioning of the genes.

Continued on page 2


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