Molecular Basis of Inheritance
Read the following passage carefully and answer the questions given below:
In the process of translation, genetic information is translated from the language of nucleic acid polymers to the language of amino acid polymers. There is no complementarity between amino acids and nucleotides, nor can this be thought of chemically. This led to the proposal of a genetic code that would direct the sequence of amino acids during protein synthesis. In eukaryotes, monocistronic structural genes are found, in which interrupted coding sequences are present. Coding sequences, or expressed sequences, are called exons. Exons are interrupted by unexpressed sequences called introns.
The length of DNA usually depends on the number of nucleotides present in it. It is a characteristic feature of an organism. For example, a bacteriophage called φ × 174 has 5386 nucleotides, bacteriophage lambda has 48502 base pairs (bp), and Escherichia coli has 4.6 × 106 base pairs (bp). There are three major types of RNA: mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA). In eukaryotes, RNA is needed for the synthesis of proteins in ribosomes. DNA obtained from sources such as blood, blood spots, hair, skin, bone, semen, etc. has one or more polymorphisms, which are very useful in forensic applications.
Which of the following statements is not correct about polymorphism?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Polymorphism is not the basis of DNA fingerprinting.
DNA polymorphism is variation in the DNA sequence at the genetic level. It arises by mutation. When an inheritable mutation is found in a population at a high frequency, it is called DNA polymorphism. Such variation passes from parents to children. DNA polymorphism is the basis of genetic mapping of the human genome as well as of DNA fingerprinting.
(1) Polymorphism is inherited from parents to children. — A correct statement. It arises from inheritable mutations, so it is passed on.
(2) DNA polymorphism is the basis of genetic mapping. — A correct statement. The genetic map of the human genome was built on it.
(3) It is caused due to point mutation. — A correct statement. Polymorphism arises from mutations, and a single-base change is one such mutation (the SNPs of the human genome).
(4) Polymorphism is not the basis of DNA fingerprinting. — Not a correct statement. DNA fingerprinting compares the repetitive DNA of people, which differs from person to person because of polymorphism. So polymorphism is its basis.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
DNA Fingerprinting – …
