Question

Mutation is seen as defective form/functions of living things. But it can also allow us to learn/experience/explore from it. a. What is genetic mutation? b. What causes mutations? c. Describe some common chromosomal mutation and discuss why are mutations so important to living organisms.

Answer 1

a) Mutations is a change that occured in our DNA sequence , either due to mistakes when DNA is copied or as a result of environmental factors .Mutations results from the error during DNA replication , mitosis or meiosis or any other type of damages. Hugo de Vries proposed mutation theory , according to him mutations are sudden heritable changes in the genotype of an organism.

b) causes of mutations

• sponataneous mutations- this is normally occur in low frequency due to the chemical instability of purine and pyrimidine bases and also due to errors in DNA replication process. During cell division , it makes copy from its DNA , any small alteration can cause mutations .
• exposure to ultraviolet radiarion can also induces mutations. it cause the breakdown of DNA and leads to mutations .
• chemical carcinogens can also causes mutations. while smoking some chemical toxins present in the cigerette also cause mutations .

c) changes in the structure or the number of chromosomes are called chromosomal mutations , they are of four types , they are

• Deletions - loss of a segment of a chromosomes are called deletions. The deletions may be either terminal or interstitial.deletion causes Cri-du-chat syndrome in human .
• Duplications- addition of an extra segment to a chromosomes leading to the repetitions of genes are called duplications.
• Inversion- If the segment of chromosomes broken and rejoined in a inverted manner. it changes the linear order of the genes.
• translocations- in this chromosomes segments are exchanged between non homologous chromosomes .

d) Importance of mutations

• It is very important in evolutions- mutations can create variations in gene pool that help the organism to survive in intense natural environment . that leads to the evolution of organisms. These changes help them to adapt to that environment .
• some mutations are benefecial mutations - lactose tolerance , rich colour vision, resistance to HIV ,