An alteration in the base sequence of nucleic acid molecule is (a) Dislocation (b) Replication (c) Duplication (d) Mutation

At the very core of genetic information in living organisms lies the nucleic acid base sequence. This sequence is like a language composed of four letters—A (adenine), T (thymine), C (cytosine), and G (guanine)—in DNA, with RNA using U (uracil) instead of T. These letters are arranged in a specific order to form genes, which are instructions for building proteins.

The order of these bases determines the genetic information available for building and maintaining an organism, similar to the way letters of the alphabet appear in a certain order to form words and sentences. Differences in the sequences of these nucleotide bases contribute to the unique characteristics of each organism.

Understanding the nucleic acid base sequence is essential when studying biology because any changes to this sequence can have significant consequences, ranging from no effect at all to the development of diseases or new phenotypic traits.

A genetic alteration refers to any change in the genetic material of an organism. It can occur naturally or can be induced by environmental factors, such as chemicals, radiation, or even errors during cell division.

Types of Genetic Alterations

• Point mutations: Changes in a single nucleotide.
• Insertions: Extra base pairs are added into the DNA sequence.
• Deletions: Base pairs are lost from the DNA sequence.
• Copy number variations: Sections of the genome are repeated and number of copies varies.

It is these alterations that provide the raw material for evolution, as some may convey a survival advantage or disadvantage. However, not all genetic alterations will have an observable effect; some are silent or neutral, while others can be extremely harmful, leading to diseases like cancer or cystic fibrosis.

DNA replication is a critical biological process that ensures each cell contains the same genetic material as its parent cell. This process occurs before a cell divides, and it involves copying the cell's entire genome. During replication, the two strands of the DNA double helix unwind with the help of enzymes.

Steps of DNA Replication

• Initiation: The DNA strand opens up to expose the bases.
• Priming: RNA primers are added to the strands to help DNA polymerases.
• Elongation: New DNA nucleotides are added to the template strands, complementary to the original nucleotides.
• Termination: The replication is completed, and the DNA molecule is now two identical DNA molecules.

This exact copying is crucial, as errors during DNA replication can lead to mutations which in turn may cause genetic disorders or contribute to the evolution of species.