Mutation

5.3

Mutation

1. Mutation: spontaneous and random change that takes place in the genes and chromosomes that can cause changes of characteristic to the offspring who inhetits the modified genes

2. Type of mutation

Type of mutation

Explanation

Chromosome mutation

Number chromosome change

Gene mutation

Structure of gene change

Example

Chromosome mutation

Down Syndrome
Turner Syndrome
Klinefelter syndrome

Gene mutation

Colour blindness
Sickle cell anaemia
Thalassemia
Haemophilia
Albinism

3. Chromosome mutation


Explanation	Down syndrome Extra chromosome in chromosome number 21 Turner syndrome Less number of sex chromosomes Klinefelter syndrome More number of sex chromosomes
Total number of chromosomes	Down syndrome 47 Turner syndrome 45 Klinefelter syndrome 47
Characteristic	Down syndrome Physical and mental retardation Short neck Slanted eyes Short stocky body Turner syndrome A person with Turner syndrome is a female Cannot undergo the development of secondary sexual characteristic of female Sterile Klinefelter syndrome A person with Klinefelter syndrome is male Will develop female characteristic such as breasts and small testis Sterile

4. Gene mutation

Disease	Characteristic
Colour blindness	Caused by mutant recessive genes on chromosome X Patient unable to differentiate between red and green colours Usually occurs in males
Sickle cell anaemia	Caused by a recessive gene on the autosome Affected the gene responsible for production of haemoglobin Red blood cells are crescent shaped which affect the transportation of oxygen
Thalassemia	Caused by the mutation of the gene that controls the production of haemoglobin Small red blood cells and the lifespan of the cells is short Can cause severe blood deficiency
Haemophilia	Caused by mutation on the gene producing the blood clotting factor Difficulty in the clotting in blood Patient will lose blood continuously if wonded or injured

5. Factors that cause mutation

Natural
Pregnancy at a late age
Carcinogens
Ultraviolet rays
X-rays
Radioactive rays

6. Genetic screening

To detect gene disorder disease
Examples:
- Karyototyping - to test the number, size and shape of chromosomes in the nucleus of a cell
- Amniocentesis - to identify foetal cell abnormalities from 15th to the 20th week of pregnancy

7. Application of genetic research to improve quality of life

Field	Application & Description
Medical	Gene therapy To treat or replace gene disorder disease with healthy gene
Agriculture	Genetic modified food Produce crops and livestck that mature quickly High quality and quantity of yield High resistace towards disease
Forensic science	DNA test for genetic genealogy Carries out the study on crime investigation by identifying and confirming the chronology of an incident based on scientific evidence obtained

Mutation

Chapter : Genetics

Topic : Mutation

Related notes