الطفرة الجينية.. تغير مفاجئ وثابت في التركيب الكيميائي لجين واحد أو أكثر يؤدي إلى تغير في الصفة الوراثية المسئول عنها ذلك الجين

الطفرة الجينية Gene mutation:
هو تغير مفاجئ وثابت في التركيب الكيميائي لجين واحد أو أكثر، يؤدي إلى تغير في الصفة الوراثية المسئول عنها ذلك الجين.
اثنان من أشكال حدوث الطفرة:
• بشكل تلقائي من الطبيعة.
• بشكل اصطناعي.

A Mutation occurs when a DNA gene is damaged or changed in such a way as 

to alter the genetic message carried by that gene. 

A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed

What is a gene mutation and how do mutations occur?

A gene mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome.

Gene mutations occur in two ways: they can be inherited from a parent or acquired during a person’s lifetime. Mutations that are passed from parent to child are called hereditary mutations or germline mutations (because they are present in the egg and sperm cells, which are also called germ cells). This type of mutation is present throughout a person’s life in virtually every cell in the body.