Arpita Srivastava Content Writer
Content Writer
Chromosomal Abnormalities is a type of abnormality that is caused by the change in one or more genetic chromosomes. In these abnormalities, the chromosome is either missing or present in extra quantities.
- Chromosomal Abnormalities are also known as Chromosomal Anomaly or Chromosomal Mutations.
- Chromosomes are thread-like structures formed from protein and nucleic acids, which are found in all living organisms.
- They are responsible for carrying genetic information from one place to another.
- It plays a major role in transferring and maintaining of genetic data.
- It involves a change in the chromosomal segment that is caused by more than one gene.
- Chromosomal abnormalities can be calculated by comparing the karyotype of an individual.
- Some habits are inherited by birth, whereas some abnormalities are caused by genetics.
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Key Terms: Chromosomal Abnormalities, Chromosomes, Protein, Nucleic acid, Cytokinesis, Cell division, Polyploidy, Aneuploidy
What are Chromosomal Abnormalities?
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Chromosomal abnormalities, mostly known as genetic disorders, mainly occur due to abnormal arrangement of chromosomes or changes in chromosomes. These types of abnormalities can occur during the early stage of development of the fetus.
- Chromosomal Abnormalities can be divided into two types, namely Numerical Abnormalities and Structural Abnormalities.
- Numerical Abnormality arises when one chromosome is absent from a pair of chromosomes.
- Structural Abnormality arises when chromosomal segments break and rejoin in the fetus.
- The problem of chromosomal abnormalities usually arises when there is an error in cell division.
- The cell division takes place at the time of either meiosis or mitosis.
- Different types of chromosomal abnormalities will lead to different types of disorders.
Chromosomal Abnormalities
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Types of Chromosomal Abnormalities
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Chromosomal abnormalities are divided into two types, which are as follows:
Numerical Abnormalities
Numerical Abnormality is a type of abnormality when there is a change in a particular number of chromosomes. When there is more than one chromosome in a pair, it is called trisomy. The numerical abnormalities are divided into three categories, which are as follows:
Polyploidy
Polyploidy mainly occurs in plants in which the count of chromosomes entirely increases due to the failure of cytokinesis in cell division. It creates the same set of chromosomes, which finally increases abnormalities information.
Aneuploidy
Aneuploidy occurs due to the segregation of genes. It arises due to increase and decrease in chromosomes. When chromosomes break in two or get double, then the problem of breakage of chromosomes arises. This will lead to duplication of chromosomes, which in turn leads to different arrangements and abnormalities.
Mixoploidy
Mixoploidy is a condition that arises when one cell in the organism is a diploid cell and the other is a polyploidy cell. This type of problem usually occurs in adults and children.
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Structural Abnormalities
Structural Abnormalities usually arise when one or more chromosomes are altered and result in causing harm to the fetus. The structural abnormalities are divided into various categories, which are as follows:
Deletions
Deletion is a kind of abnormality when a portion of chromosome is either missing or deleted.
Duplications
Duplications are a kind of abnormality in which the number of chromosomes are duplicated, which in turn increases the genetic material within the body.
Translocations
Translocations are a kind of abnormality that occurs when the chromosome is transferred from one place to another place.
Rings
In this type of abnormality, chromosomes break inside the fetus to form various types of rings.
Inversion
It is a type of structural abnormality which arises when chromosomes break from one place and get attached to another chromosome.
Dicentric Chromosome
In this type of chromosome, two centromeres are present inside a chromosome.
Isochromosomes
This problem arises when a mirror copy of chromosomes, along with their centromere, is made.
Structural Abnormalities
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Causes of Chromosomal Abnormalities
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The various causes of chromosomal abnormalities are as follows:
- Drugs
- Some kind of medicines
- Alcohol
- Tobacco
- Toxic materials
- Some viruses and bacteria
- Some radiations
- Diabetics and other inherited diseases
- Long term exposure of chromosomes to environmental activities
- Reproduction above the age of 35
- Bad habits during pregnancies
- Errors in cell division
- Numerical and structural abnormalities in sex chromosomes
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Examples of Chromosomal Disorders
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Some examples of chromosomal disorders are as follows:
Down syndrome
Down Syndrome is a type of syndrome that occurs due to the presence of an additional chromosome 21. The extra chromosomes are formed due to abnormal cell division. It is divided into three types, namely translocation, trisomy, and mosaicism.
The symptoms of Down syndrome are as follows:
- The person is short and has a round-headed
- The physical development of an individual is stopped.
- A person may have a partially opened mouth and board palms.
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Kline Felter Syndrome
Kline Felter Syndrome usually occurs in males due to the presence of an extra X chromosome, which increases the count of chromosomes to 47. This also affects the brain functioning and intellectuality in males.
The symptoms of Kline Felter Syndrome are as follows:
- A person may develop feminist characteristics like the development of breasts
- The problem of sterility arises.
- Puberty
- Absence of secondary sexual characters.
Turner Syndrome
Turner Syndrome usually occurs in females due to the absence of an X chromosome, which increases the count of chromosomes from 46 to 45. It mainly affects their reproductive process
The symptoms of Turner Syndrome are as follows:
- Women may become sterile and may not reproduce
- It results in heart disorders, high blood pressure, and skeletal disorders
- Other changes include problems in the secretion of hormones.
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Things to Remember
- Chromosomal abnormalities are caused by the abnormal arrangement of chromosomes.
- It mainly occurs due to inappropriate cell division in organisms.
- The abnormalities are also found in plants.
- Plants suffering from chromosomal abnormalities may suffer undergrowth of stems, which affects the bearing
- These types of abnormalities have no cure.
- Medicines can reduce their effect up to a certain extent.
- Bad habits and some other disorders increase chromosomal abnormalities
- Some diseases, such as diabetes, are inherited from elders.
- Any genetic disorders also lead to cancers at a young age.
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Sample Questions
Ques: Explain chromosomes, their quantity, and their formation in the human body? (3 marks)
Ans: Chromosomes are the DNA structures that contain our genes. These thread-like structures contain long strings of DNA containing hundreds of connected genes.
- Cells contain 46 chromosomes, which are arranged in 23 pairs.
- During the formation of a cell, one cell comes from the mother and another from the father.
- It exhibits the characteristics of the most dominant genes.
Ques: How are the chromosomes decided for each cell of the human body? (2 marks)
Ans: As we know, chromosomes hold our genetic characteristics. All of our cells consist of 23 pairs of 46 chromosomes, but in our nerve cell, we have only 46 chromosomes. Each cell of the body should have the required number of chromosomes; otherwise, it will lead to problems with growth.
Ques: Explain about recombination process and how chromosomes are involved in it? (2 marks)
Ans: Recombination is a process in which our DNA is broken and recombined to form a new combination of genetic material. This process is called a cross-over, and this will result in the exchange of genetic material between both parents, which further result in different combination of genes in chromosomes.
Ques: Explain the procedure of DNA tests? (2 marks)
Ans: In DNA tests, our chromosomes are tested, and the characters which are derived from our parents are also determined. Lab specialists examine the characters by observing your chromosomes under a microscope.
Ques: Explain treatment in case of chromosomal abnormalities? (3 marks)
Ans: Currently, there is no treatment in the case of chromosomal abnormalities, but some counselling therapies, such as physical therapy and occupational therapy, are proven effective over these diseases. These are long-term disorders and sometimes prevail over a lifetime; if any person from your family is affected by this and cured after some age, then there are chances for you to cure it.
Ques. What are different techniques used for the detection of chromosomal abnormalities? (3 marks)
Ans. The different techniques used for detection of chromosomal abnormalities are as follows:
- For prenatal diagnosis of the fetus, chorionic villus sampling or circulating foetal cells would be conducted in order to check for chromosomal abnormalities.
- During the preimplantational diagnosis of an embryo, a blastocyst biopsy would be conducted in order to check for chromosomal abnormalities.
- To check for abnormalities like lymphoma or leukaemia, a bone marrow biopsy is conducted.
Ques. What are the main causes of chromosomal abnormalities? (3 marks)
Ans. The main causes of chromosomal abnormalities are as follows:
- Drugs
- Some kinds of medicines
- Alcohol
- Tobacco
- Toxic materials
- Viruses and Bacteria
- Long-term exposure of chromosomes to environmental activities
- Reproduction above the age of 35
- Bad habits during pregnancies
- Errors in cell division
Ques. Explain the type of structural abnormalities? (4 marks)
Ans. The types of structural abnormalities are as follows:
- Deletions: Deletion is a kind of structural abnormality when a portion of chromosome is either missing or deleted.
- Duplications: Duplications are a kind of structural abnormality in which the number of chromosomes are duplicated. This will increase the genetic material within the body.
- Translocations: Translocations are a kind of abnormality that occurs when the chromosome is transferred from one place to another place.
- Rings: Ring is a type of abnormality where chromosomes break inside the fetus to form various types of rings.
- Inversion: Inversion is a type of structural abnormality which arises when chromosomes break from one place and get attached to another chromosome.
- Dicentric Chromosome: Dicentric Chromosome is a type of chromosome; two centromeres are present inside a chromosome.
- Isochromosomes: Isochromosomes problem arises when a mirror copy of chromosomes, along with their centromere, is made.
Ques. Explain the type of translocation abnormalities? (2 marks)
Ans. Translocations is a type of structural abnormalities where one chromsome is transferred from one place to another. It is divided into two categories which are as follows:
- Reciprocal translocation: In this type of translocation method, two segments of chromosomes are exchanged in the fetus.
- Robertsonian translocation: In this type of translocation method, a chromosome get attached to the another chromosomes.
Ques. What are the different types of numerical abnormalities? (3 marks)
Ans. The different types of numerical abnormalities are as follows:
- Polyploidy: It mainly occurs in plants in which the count of chromosomes entirely increases due to the failure of cytokinesis in cell division.
- Aneuploidy: It occurs due to the segregation of genes. Aneuploidy arises due to increase and decrease in chromosomes. When chromosomes break in two or get double, then the problem of breakage of chromosomes arises. This will lead to duplication of chromosomes, which in turn leads to different arrangements and abnormalities.
- Mixoploidy: It is a condition that arises when one cell in the organism is a diploid cell and the other is a polyploidy cell. This type of problem usually occurs in adults and children.
Ques. What is Turner Syndrome? (3 marks)
Ans.Turner Syndrome, also known as 45X or 45X0, is a type of genetic problem found in females. The problem arises when one of the sex chromosomes or X chromosome is either missing or partially missing from female cells. These types of women may not have a menstrual period and are not able to conceive a child without the use of technology.
Some symptoms of Turner Syndrome are as follows:
- Women may become sterile and may not reproduce.
- They develop a low hairline at the back of the neck.
- It results in heart disorders, high blood pressure, and skeletal disorders
- Swollen hands and feet at the time of childbirth.
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