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Mutation

5.3 Mutation
SCIENCE • Form 4 • Chapter 5: Genetics

5.3 Mutation

Mutation is a spontaneous and random change in the genes or chromosomes of an organism that can alter the physical and physiological traits inherited by offspring.

Learning Objectives

  • Define mutation and identify the two types of mutations: chromosome mutation and gene mutation.
  • Describe examples of chromosome mutations and gene mutations.
  • Identify external factors (mutagens) and natural factors that cause mutations.
  • Analyse the inheritance of sex-linked gene disorders using schematic diagrams.
  • Explain the diagnostic methods used to detect gene disorder diseases.
  • Describe the applications of genetic research and the effects and ethical issues related to genetic research.

Comparison of Human Karyotypes in Chromosome Mutations

Identify the specific chromosomal abnormalities characterising Down syndrome, Turner syndrome and Klinefelter syndrome.

Comparison of human karyotypes in chromosome mutations A three-column diagram comparing chromosome pair 21 and pair 23 in Down syndrome, Turner syndrome and Klinefelter syndrome. Down syndrome shows three copies of chromosome 21. Turner syndrome shows a single X chromosome. Klinefelter syndrome shows two X chromosomes and one Y chromosome. Down syndrome Turner syndrome Klinefelter syndrome Trisomy 21 • 47 chromosomes XO • 45 chromosomes XXY • 47 chromosomes Pair 21: three copies Pair 23: one X only Pair 23: two X + one Y

Short Explanation

Definition

Mutation is a spontaneous and random change that takes place in the genes and chromosomes that can cause changes of characteristics to the offspring who inherits the modified genes.

There are two main types of mutation: chromosome mutation and gene mutation. Chromosome mutation occurs when there are changes in the number or structure of chromosomes, resulting from defects during the cell division process. Gene mutation is caused by chemical changes that occur within a specific gene, altering the traits controlled by that gene.

Chromosome Mutation

Changes in the number or structure of chromosomes. Examples include Down syndrome, Turner syndrome and Klinefelter syndrome.

Gene Mutation

Chemical changes within a specific gene. Examples include colour blindness, sickle cell anaemia, thalassemia and haemophilia.

Chromosome Mutation Examples

Comparison of chromosome mutations and their characteristics.
Disorder Chromosome count Characteristics
Down syndrome \(47\) chromosomes (\(45 + \text{XY}\) or \(45 + \text{XX}\), with \(3\) copies of chromosome \(21\)) Physical and mental retardation, short neck, slanted eyes, short stocky body. Risk increases if the mother’s age is over \(35\).
Turner syndrome \(45\) chromosomes (\(44 + \text{XO}\)) A female who lacks one sex chromosome. Does not develop secondary sexual characteristics of a female; sterile.
Klinefelter syndrome \(47\) chromosomes (\(44 + \text{XXY}\)) A male with an extra \(\text{X}\) chromosome. Exhibits female characteristics such as enlarged breasts, small testes, and is sterile.

Gene Mutation Examples

Comparison of gene mutations and their characteristics.
Disorder Cause Characteristics
Colour blindness Mutant recessive gene located on the \(\text{X}\) chromosome. Affected individuals cannot differentiate between red and green. More commonly occurs in males.
Sickle cell anaemia Spontaneous mutation in the gene responsible for haemoglobin production; recessive gene on an autosome. Red blood cells become sickle-shaped, which impairs oxygen transport.
Thalassemia Mutation in the gene controlling haemoglobin production. Red blood cells are smaller than normal and have a shorter lifespan, leading to severe blood deficiency.
Haemophilia Mutation in the gene producing the blood clotting factor; recessive allele on the \(\text{X}\) chromosome. Blood takes a longer time to clot; patients experience continuous bleeding when wounded or injured.

Factors that Cause Mutation (Mutagens)

Mutations can occur spontaneously during cell division or be induced by external agents called mutagens.

  • Natural causes: Spontaneous errors during cell division.
  • Biological / Age factor: Pregnancy at a late age, for example above \(35\) years old.
  • Physical factors: Radioactive rays, X-rays, ultraviolet (\(\text{UV}\)) rays.
  • Chemical factors: Carcinogens.

Inheritance of Sex-Linked Gene Disorders

Sex-linked traits are controlled by genes located on sex chromosomes, specifically the \(\text{X}\) chromosome.

Allele notation for haemophilia: \(X^H\) is the dominant allele (normal), and \(X^h\) is the recessive allele (haemophilia).

  • Normal female: \(X^H X^H\)
  • Carrier female: \(X^H X^h\)
  • Haemophiliac female: \(X^h X^h\)
  • Normal male: \(X^H Y\)
  • Haemophiliac male: \(X^h Y\)

Schematic Cross 1: Normal Father × Carrier Mother

Father \(X^H Y\) produces gametes \(X^H\) and \(Y\). Mother \(X^H X^h\) produces gametes \(X^H\) and \(X^h\).

Offspring genotypes: \(X^H X^H\), \(X^H X^h\), \(X^H Y\), \(X^h Y\).

Offspring phenotypes: \(1\) normal daughter, \(1\) carrier daughter, \(1\) normal son, \(1\) haemophiliac son.

Schematic Cross 2: Normal Father × Haemophiliac Mother

Father \(X^H Y\) produces gametes \(X^H\) and \(Y\). Mother \(X^h X^h\) produces gametes \(X^h\) and \(X^h\).

Offspring genotypes: \(X^H X^h\), \(X^H X^h\), \(X^h Y\), \(X^h Y\).

Offspring phenotypes: All daughters are carriers (\(X^H X^h\)); all sons are haemophiliacs (\(X^h Y\)).

Methods to Detect Gene Disorder Diseases

Two primary clinical methods are used to detect chromosomal and genetic abnormalities at an early stage: amniocentesis and karyotyping.

Amniocentesis

Used between the \(15\text{th}\) and \(20\text{th}\) week of pregnancy.

  1. An ultrasound is performed to ensure a safe fetal position. A needle is inserted carefully through the mother’s abdominal wall into the uterus.
  2. Amniotic fluid containing floating foetal cells is extracted.
  3. The amniotic fluid is centrifuged to separate the fluid from the foetal cells.
  4. The isolated foetal cells are cultured and used to obtain a karyotype.

Karyotyping

  1. A sample of foetal cells or body tissue is collected.
  2. The cells are incubated for \(2\) to \(3\) days.
  3. A chemical is added to stimulate mitosis.
  4. Another chemical is added to halt mitosis at the metaphase stage.
  5. Cells are transferred to a centrifuge tube and spun to concentrate them.
  6. The concentrated cells are placed in a tube containing fixative.
  7. The cell suspension is dropped onto a microscope slide and stained with dye to make chromosomes visible.
  8. The slide is examined under a microscope, and a photograph of the chromosomes is taken.
  9. The photograph is cut and arranged into homologous pairs according to size and shape to form a karyotype.

Application of Genetic Research to Improve Quality of Life

Forensic Science

Uses DNA analysis to investigate crimes by verifying the chronology of incidents and matching physical evidence from crime scenes or suspects for presentation in court.

Gene Therapy

An experimental technique aimed at repairing defective or mutated genes causing disorders such as cystic fibrosis, haemophilia and sickle cell anaemia.

Mechanism:

  1. Stem cells are extracted from the patient.
  2. A normal, functioning gene is inserted into a carrier virus.
  3. The modified virus is added to the patient's stem cells to transfer the normal gene into them.
  4. The patient's stem cells become genetically modified.
  5. The genetically modified cells are injected back into the patient.
  6. The modified cells produce the desired normal protein or hormone.

Genetic Genealogy

Involves DNA testing to trace human ancestry, family pedigrees and historical lineages.

Effects and Ethical Issues of Genetic Research

Genetic research provides benefits in medicine and agriculture, but presents dilemmas regarding:

  • Economy: Issues concerning health insurance eligibility and employment discrimination based on genetic screenings.
  • Welfare & Psychology: Stress or distress caused by knowing genetic predispositions; impact on family dynamics.
  • Ethics & Social Values: Alteration of human genomes, privacy of genetic data, and potential discrimination against carriers of genetic disorders.

Try to Answer First

Answer in your mind, then press “Check Answer”.

1

What is the difference in chromosome numbers between an individual with Down syndrome and an individual with Turner syndrome?

Answer: An individual with Down syndrome has \(47\) chromosomes (an extra autosome at chromosome \(21\)), whereas an individual with Turner syndrome has \(45\) chromosomes (missing one sex chromosome, \(\text{XO}\)).
2

Why are sex-linked genetic diseases such as haemophilia and colour blindness more commonly found in males than in females?

Answer: The alleles causing these diseases are recessive and located on the \(\text{X}\) chromosome. Males have only one \(\text{X}\) chromosome (\(\text{XY}\)), so receiving a single recessive allele causes the condition. Females have two \(\text{X}\) chromosomes (\(\text{XX}\)) and will only exhibit the condition if they inherit two copies of the recessive allele.
3

During the process of karyotyping, at which stage of cell division is mitosis stopped, and why?

Answer: Mitosis is stopped at the metaphase stage because during metaphase, chromosomes are fully condensed, most distinct, and clearly visible under a microscope.

Common Mistakes

  • !Classifying Down syndrome as a gene mutation. Down syndrome is a chromosome mutation because it involves an entire extra chromosome \(21\). Thalassemia and haemophilia are gene mutations because they involve chemical sequence changes within specific genes.
  • !Writing that Turner syndrome has \(45\) autosomes. In fact, Turner syndrome has \(44\) autosomes and \(1\) sex chromosome (\(44 + \text{XO} = 45\) total).
  • !Identifying a male as a “carrier” for colour blindness or haemophilia. Males cannot be carriers for \(\text{X}\)-linked recessive disorders because they carry only one \(\text{X}\) chromosome; they are either completely normal or affected sufferers.

Concept Misunderstandings

Misconception

All mutations are immediately fatal or harmful to an organism.

Correct Concept

Mutations are simply changes in genetic code; some cause non-fatal variations or diseases, while others can be neutral.

Misconception

Amniocentesis directly repairs the defective genes of a fetus.

Correct Concept

Amniocentesis is strictly a diagnostic procedure used to extract amniotic fluid and foetal cells to identify chromosomal abnormalities; it does not treat or repair genes.

Misconception

Gene therapy changes every single cell in the entire human body at once.

Correct Concept

Gene therapy extracts specific stem cells from a patient, introduces the correct gene using a modified viral vector in the lab, and then re-injects these modified cells into the body to produce the missing protein.

Summary

  • Mutation is a spontaneous, random change in genes or chromosomes.
  • Chromosome mutations alter chromosome number or structure: Down syndrome (\(47\) chromosomes, extra chromosome \(21\)), Turner syndrome (\(45\) chromosomes, \(44 + \text{XO}\)), Klinefelter syndrome (\(47\) chromosomes, \(44 + \text{XXY}\)).
  • Gene mutations alter chemical sequences in genes: colour blindness, sickle cell anaemia, thalassemia and haemophilia.
  • Mutagens include \(\text{UV}\) rays, X-rays, radioactive rays, carcinogens, and older maternal age (\(>35\)).
  • Diagnostic methods: Amniocentesis (fluid extraction at \(15\text{th}\)–\(20\text{th}\) weeks) and Karyotyping (arranging metaphase chromosomes).
  • Genetic research applications: Forensic science, gene therapy and genetic genealogy.

Short Activity

A. Objective Quiz

1 A karyotype analysis shows that a patient has a total of 47 chromosomes with the sex chromosome composition XXY. What genetic disorder does this person have?

2 Which of the following is a gene mutation caused by a recessive allele located on an autosome?

B. Fill in the Blanks

3 The clinical procedure carried out between the 15th and 20th week of pregnancy to extract amniotic fluid containing foetal cells is called .

 

4 External physical or chemical agents that can cause gene or chromosome mutations are known as .

 

C. Drag and Drop: Match the Disorder to Its Genetic Characteristic

Drag each disorder to its correct underlying cause or genetic characteristic. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.

Disorder
Down syndrome
Turner syndrome
Haemophilia
Thalassemia
Genetic Characteristic
1 Extra chromosome at chromosome number 21
2 Female with a missing X chromosome (44 + XO)
3 Inability to produce blood clotting factor due to an X-linked recessive gene
4 Production of smaller red blood cells with shorter lifespan due to defective haemoglobin gene

C. Match the Disorder to Its Genetic Characteristic

Write the correct disorder next to each genetic characteristic.

Genetic Characteristic Disorder
1. Extra chromosome at chromosome number 21 
2. Female with a missing X chromosome (44 + XO) 
3. Inability to produce blood clotting factor due to an X-linked recessive gene 
4. Production of smaller red blood cells with shorter lifespan due to defective haemoglobin gene 

Answer choices: Down syndrome • Turner syndrome • Haemophilia • Thalassemia

Keywords

Mutation Mutagen Chromosome Mutation Gene Mutation Down syndrome Turner syndrome Klinefelter syndrome Sex-linked trait Amniocentesis Karyotype Gene Therapy Genetic Genealogy
The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.

Mutation

5.3 Mutation
SCIENCE • Form 4 • Chapter 5: Genetics

5.3 Mutation

Mutation is a spontaneous and random change in the genes or chromosomes of an organism that can alter the physical and physiological traits inherited by offspring.

Learning Objectives

  • Define mutation and identify the two types of mutations: chromosome mutation and gene mutation.
  • Describe examples of chromosome mutations and gene mutations.
  • Identify external factors (mutagens) and natural factors that cause mutations.
  • Analyse the inheritance of sex-linked gene disorders using schematic diagrams.
  • Explain the diagnostic methods used to detect gene disorder diseases.
  • Describe the applications of genetic research and the effects and ethical issues related to genetic research.

Comparison of Human Karyotypes in Chromosome Mutations

Identify the specific chromosomal abnormalities characterising Down syndrome, Turner syndrome and Klinefelter syndrome.

Comparison of human karyotypes in chromosome mutations A three-column diagram comparing chromosome pair 21 and pair 23 in Down syndrome, Turner syndrome and Klinefelter syndrome. Down syndrome shows three copies of chromosome 21. Turner syndrome shows a single X chromosome. Klinefelter syndrome shows two X chromosomes and one Y chromosome. Down syndrome Turner syndrome Klinefelter syndrome Trisomy 21 • 47 chromosomes XO • 45 chromosomes XXY • 47 chromosomes Pair 21: three copies Pair 23: one X only Pair 23: two X + one Y

Short Explanation

Definition

Mutation is a spontaneous and random change that takes place in the genes and chromosomes that can cause changes of characteristics to the offspring who inherits the modified genes.

There are two main types of mutation: chromosome mutation and gene mutation. Chromosome mutation occurs when there are changes in the number or structure of chromosomes, resulting from defects during the cell division process. Gene mutation is caused by chemical changes that occur within a specific gene, altering the traits controlled by that gene.

Chromosome Mutation

Changes in the number or structure of chromosomes. Examples include Down syndrome, Turner syndrome and Klinefelter syndrome.

Gene Mutation

Chemical changes within a specific gene. Examples include colour blindness, sickle cell anaemia, thalassemia and haemophilia.

Chromosome Mutation Examples

Comparison of chromosome mutations and their characteristics.
Disorder Chromosome count Characteristics
Down syndrome \(47\) chromosomes (\(45 + \text{XY}\) or \(45 + \text{XX}\), with \(3\) copies of chromosome \(21\)) Physical and mental retardation, short neck, slanted eyes, short stocky body. Risk increases if the mother’s age is over \(35\).
Turner syndrome \(45\) chromosomes (\(44 + \text{XO}\)) A female who lacks one sex chromosome. Does not develop secondary sexual characteristics of a female; sterile.
Klinefelter syndrome \(47\) chromosomes (\(44 + \text{XXY}\)) A male with an extra \(\text{X}\) chromosome. Exhibits female characteristics such as enlarged breasts, small testes, and is sterile.

Gene Mutation Examples

Comparison of gene mutations and their characteristics.
Disorder Cause Characteristics
Colour blindness Mutant recessive gene located on the \(\text{X}\) chromosome. Affected individuals cannot differentiate between red and green. More commonly occurs in males.
Sickle cell anaemia Spontaneous mutation in the gene responsible for haemoglobin production; recessive gene on an autosome. Red blood cells become sickle-shaped, which impairs oxygen transport.
Thalassemia Mutation in the gene controlling haemoglobin production. Red blood cells are smaller than normal and have a shorter lifespan, leading to severe blood deficiency.
Haemophilia Mutation in the gene producing the blood clotting factor; recessive allele on the \(\text{X}\) chromosome. Blood takes a longer time to clot; patients experience continuous bleeding when wounded or injured.

Factors that Cause Mutation (Mutagens)

Mutations can occur spontaneously during cell division or be induced by external agents called mutagens.

  • Natural causes: Spontaneous errors during cell division.
  • Biological / Age factor: Pregnancy at a late age, for example above \(35\) years old.
  • Physical factors: Radioactive rays, X-rays, ultraviolet (\(\text{UV}\)) rays.
  • Chemical factors: Carcinogens.

Inheritance of Sex-Linked Gene Disorders

Sex-linked traits are controlled by genes located on sex chromosomes, specifically the \(\text{X}\) chromosome.

Allele notation for haemophilia: \(X^H\) is the dominant allele (normal), and \(X^h\) is the recessive allele (haemophilia).

  • Normal female: \(X^H X^H\)
  • Carrier female: \(X^H X^h\)
  • Haemophiliac female: \(X^h X^h\)
  • Normal male: \(X^H Y\)
  • Haemophiliac male: \(X^h Y\)

Schematic Cross 1: Normal Father × Carrier Mother

Father \(X^H Y\) produces gametes \(X^H\) and \(Y\). Mother \(X^H X^h\) produces gametes \(X^H\) and \(X^h\).

Offspring genotypes: \(X^H X^H\), \(X^H X^h\), \(X^H Y\), \(X^h Y\).

Offspring phenotypes: \(1\) normal daughter, \(1\) carrier daughter, \(1\) normal son, \(1\) haemophiliac son.

Schematic Cross 2: Normal Father × Haemophiliac Mother

Father \(X^H Y\) produces gametes \(X^H\) and \(Y\). Mother \(X^h X^h\) produces gametes \(X^h\) and \(X^h\).

Offspring genotypes: \(X^H X^h\), \(X^H X^h\), \(X^h Y\), \(X^h Y\).

Offspring phenotypes: All daughters are carriers (\(X^H X^h\)); all sons are haemophiliacs (\(X^h Y\)).

Methods to Detect Gene Disorder Diseases

Two primary clinical methods are used to detect chromosomal and genetic abnormalities at an early stage: amniocentesis and karyotyping.

Amniocentesis

Used between the \(15\text{th}\) and \(20\text{th}\) week of pregnancy.

  1. An ultrasound is performed to ensure a safe fetal position. A needle is inserted carefully through the mother’s abdominal wall into the uterus.
  2. Amniotic fluid containing floating foetal cells is extracted.
  3. The amniotic fluid is centrifuged to separate the fluid from the foetal cells.
  4. The isolated foetal cells are cultured and used to obtain a karyotype.

Karyotyping

  1. A sample of foetal cells or body tissue is collected.
  2. The cells are incubated for \(2\) to \(3\) days.
  3. A chemical is added to stimulate mitosis.
  4. Another chemical is added to halt mitosis at the metaphase stage.
  5. Cells are transferred to a centrifuge tube and spun to concentrate them.
  6. The concentrated cells are placed in a tube containing fixative.
  7. The cell suspension is dropped onto a microscope slide and stained with dye to make chromosomes visible.
  8. The slide is examined under a microscope, and a photograph of the chromosomes is taken.
  9. The photograph is cut and arranged into homologous pairs according to size and shape to form a karyotype.

Application of Genetic Research to Improve Quality of Life

Forensic Science

Uses DNA analysis to investigate crimes by verifying the chronology of incidents and matching physical evidence from crime scenes or suspects for presentation in court.

Gene Therapy

An experimental technique aimed at repairing defective or mutated genes causing disorders such as cystic fibrosis, haemophilia and sickle cell anaemia.

Mechanism:

  1. Stem cells are extracted from the patient.
  2. A normal, functioning gene is inserted into a carrier virus.
  3. The modified virus is added to the patient's stem cells to transfer the normal gene into them.
  4. The patient's stem cells become genetically modified.
  5. The genetically modified cells are injected back into the patient.
  6. The modified cells produce the desired normal protein or hormone.

Genetic Genealogy

Involves DNA testing to trace human ancestry, family pedigrees and historical lineages.

Effects and Ethical Issues of Genetic Research

Genetic research provides benefits in medicine and agriculture, but presents dilemmas regarding:

  • Economy: Issues concerning health insurance eligibility and employment discrimination based on genetic screenings.
  • Welfare & Psychology: Stress or distress caused by knowing genetic predispositions; impact on family dynamics.
  • Ethics & Social Values: Alteration of human genomes, privacy of genetic data, and potential discrimination against carriers of genetic disorders.

Try to Answer First

Answer in your mind, then press “Check Answer”.

1

What is the difference in chromosome numbers between an individual with Down syndrome and an individual with Turner syndrome?

Answer: An individual with Down syndrome has \(47\) chromosomes (an extra autosome at chromosome \(21\)), whereas an individual with Turner syndrome has \(45\) chromosomes (missing one sex chromosome, \(\text{XO}\)).
2

Why are sex-linked genetic diseases such as haemophilia and colour blindness more commonly found in males than in females?

Answer: The alleles causing these diseases are recessive and located on the \(\text{X}\) chromosome. Males have only one \(\text{X}\) chromosome (\(\text{XY}\)), so receiving a single recessive allele causes the condition. Females have two \(\text{X}\) chromosomes (\(\text{XX}\)) and will only exhibit the condition if they inherit two copies of the recessive allele.
3

During the process of karyotyping, at which stage of cell division is mitosis stopped, and why?

Answer: Mitosis is stopped at the metaphase stage because during metaphase, chromosomes are fully condensed, most distinct, and clearly visible under a microscope.

Common Mistakes

  • !Classifying Down syndrome as a gene mutation. Down syndrome is a chromosome mutation because it involves an entire extra chromosome \(21\). Thalassemia and haemophilia are gene mutations because they involve chemical sequence changes within specific genes.
  • !Writing that Turner syndrome has \(45\) autosomes. In fact, Turner syndrome has \(44\) autosomes and \(1\) sex chromosome (\(44 + \text{XO} = 45\) total).
  • !Identifying a male as a “carrier” for colour blindness or haemophilia. Males cannot be carriers for \(\text{X}\)-linked recessive disorders because they carry only one \(\text{X}\) chromosome; they are either completely normal or affected sufferers.

Concept Misunderstandings

Misconception

All mutations are immediately fatal or harmful to an organism.

Correct Concept

Mutations are simply changes in genetic code; some cause non-fatal variations or diseases, while others can be neutral.

Misconception

Amniocentesis directly repairs the defective genes of a fetus.

Correct Concept

Amniocentesis is strictly a diagnostic procedure used to extract amniotic fluid and foetal cells to identify chromosomal abnormalities; it does not treat or repair genes.

Misconception

Gene therapy changes every single cell in the entire human body at once.

Correct Concept

Gene therapy extracts specific stem cells from a patient, introduces the correct gene using a modified viral vector in the lab, and then re-injects these modified cells into the body to produce the missing protein.

Summary

  • Mutation is a spontaneous, random change in genes or chromosomes.
  • Chromosome mutations alter chromosome number or structure: Down syndrome (\(47\) chromosomes, extra chromosome \(21\)), Turner syndrome (\(45\) chromosomes, \(44 + \text{XO}\)), Klinefelter syndrome (\(47\) chromosomes, \(44 + \text{XXY}\)).
  • Gene mutations alter chemical sequences in genes: colour blindness, sickle cell anaemia, thalassemia and haemophilia.
  • Mutagens include \(\text{UV}\) rays, X-rays, radioactive rays, carcinogens, and older maternal age (\(>35\)).
  • Diagnostic methods: Amniocentesis (fluid extraction at \(15\text{th}\)–\(20\text{th}\) weeks) and Karyotyping (arranging metaphase chromosomes).
  • Genetic research applications: Forensic science, gene therapy and genetic genealogy.

Short Activity

A. Objective Quiz

1 A karyotype analysis shows that a patient has a total of 47 chromosomes with the sex chromosome composition XXY. What genetic disorder does this person have?

2 Which of the following is a gene mutation caused by a recessive allele located on an autosome?

B. Fill in the Blanks

3 The clinical procedure carried out between the 15th and 20th week of pregnancy to extract amniotic fluid containing foetal cells is called .

 

4 External physical or chemical agents that can cause gene or chromosome mutations are known as .

 

C. Drag and Drop: Match the Disorder to Its Genetic Characteristic

Drag each disorder to its correct underlying cause or genetic characteristic. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.

Disorder
Down syndrome
Turner syndrome
Haemophilia
Thalassemia
Genetic Characteristic
1 Extra chromosome at chromosome number 21
2 Female with a missing X chromosome (44 + XO)
3 Inability to produce blood clotting factor due to an X-linked recessive gene
4 Production of smaller red blood cells with shorter lifespan due to defective haemoglobin gene

C. Match the Disorder to Its Genetic Characteristic

Write the correct disorder next to each genetic characteristic.

Genetic Characteristic Disorder
1. Extra chromosome at chromosome number 21 
2. Female with a missing X chromosome (44 + XO) 
3. Inability to produce blood clotting factor due to an X-linked recessive gene 
4. Production of smaller red blood cells with shorter lifespan due to defective haemoglobin gene 

Answer choices: Down syndrome • Turner syndrome • Haemophilia • Thalassemia

Keywords

Mutation Mutagen Chromosome Mutation Gene Mutation Down syndrome Turner syndrome Klinefelter syndrome Sex-linked trait Amniocentesis Karyotype Gene Therapy Genetic Genealogy
The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.
Chapter : Genetics
Topic : Debate the effects of genetics research to human life
Form 4 Science
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