Question

how does the DNA resist changes?is there any process which does that?

Answer 1

One most impressive property of DNA is its stability. Some cells in the body which differentiate into specialist cells early in life, e.g. neurones (nerve cells) and skeletal muscle cells, exist without dividing for the term of your natural life. This means that they make no new copies of DNA and therefore use the same DNA for many decades. The DNA strands in the nerve cells of a 100 year old person have been there for 100 years. This stability is due to the very complex protective folding and packaging of the DNA strands, as well as many surveillance and repair mechanisms. DNA seems built to last.

Living organisms also have many mechanisms which enable them to resist change to genetic information. These include:

Double Copy

DNA is double stranded. When a cell divides each new cell receives DNA containing one of the original strands plus a newly made reciprocal copy. Its information is coded twice using a matching reciprocal code on each strand, e.g. A (Adenine) on one strand is coded by T (Thymine) on the other strand; G on one strand is always matched with C.

Positive Redundancy

DNA uses a code which has 4 chemical letters T, C, A, G which are used 3 at a time. Each combination of 3 code letters is called a codon. Four different letters used 3 at a time means there are 64 possible combinations of letters. Since only 20 amino acids are used by DNA via RNA to make protein, many amino acids have more than one way of being 'spelt'. (Some amino acids, such as Argenine, Leucine and Serine, have 6 different codons.) This enables plenty of ways to back up information.

http://evidenceweb.net/originoflife/chapter12.htm

Answer 2

well,i still don't find a mechanism here!the info just gives the details about the nature of DNA and not about the mechanism!well,i do knw about the double stranded nature and complimentary pairing and the codon proposed by gamow!but there must b a reason behind all this giving stability to the DNA!
and thanks !:)

Answer 3

no problemo