Example of Non-Mendelian disorder:
Example of Non-Mendelian disorder:
- Cystic fibrosis
- Haemophilia
- Down’s syndrome
- Thalassemia
The Correct Option is C
Approach Solution - 1
First, let's define Mendelian and Non-Mendelian disorders:
- Mendelian Disorders: These are genetic disorders caused by mutations in a single gene and follow the laws of Mendelian inheritance (dominant, recessive, X-linked). Examples include Cystic Fibrosis, Haemophilia, and Thalassemia.
- Non-Mendelian Disorders: These disorders do not follow simple Mendelian patterns of inheritance. They often involve multiple genes, environmental factors, or chromosomal abnormalities.
Now let's analyze the options:
- Cystic Fibrosis: This is an autosomal recessive disorder caused by a mutation in the CFTR gene. It follows Mendelian inheritance.
- Haemophilia: This is typically an X-linked recessive disorder caused by mutations in genes responsible for blood clotting. It follows Mendelian inheritance.
- Down's syndrome: This is a chromosomal disorder caused by the presence of an extra copy of chromosome 21 (Trisomy 21). It does NOT follow Mendelian inheritance patterns. The extra chromosome arises due to errors in chromosome segregation during meiosis (nondisjunction).
- Thalassemia: This is a group of autosomal recessive blood disorders caused by mutations in genes responsible for producing hemoglobin. It follows Mendelian inheritance.
Therefore, the example of a Non-Mendelian disorder among the options is Down's syndrome.
Approach Solution -2
Down's syndrome is caused by the presence of an extra copy of chromosome 21, known as trisomy 21. It is not inherited in a Mendelian pattern, which typically involves the transmission of a single gene from parents to offspring. Instead, Down's syndrome occurs due to a random error during the formation of reproductive cells or early embryonic development.
Top KCET Biology Questions
- Relate Column I with Column II with regard to predatory behaviour:
Column I Column II 1. Calotropis p. Invertebrates 2. Pisaster q. Distasteful 3. Monarch butterfly r. Cryptically colored 4. Frogs s. Cardioglycoside - Small mammals and birds are rarely found in polar regions. The reason is that
Match Column I and Column I
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Top KCET Non-Mendelian Genetics Questions
Top KCET Questions
- Which of the following is not true for oxidation?
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Concepts Used:
Non-Mendelian Genetics
The term - non-mendelian inheritance refers to any pattern of heredity in which features do not separate according to Mendel's laws. These principles describe how features linked with single genes on chromosomes in the nucleus are passed down through generations.
Types of Non-Mendelian Inheritance
Codominance Inheritance
It is a form of incomplete dominance in which both alleles for the same feature are expressed in the heterozygote at the same time. For example, the MN blood types of humans.
Incomplete Dominance
In a heterozygote, the dominant allele does not always completely cover the phenotypic expression of the recessive gene, resulting in an intermediate phenotype which is referred to as "incomplete dominance”.