Describe a tautomeric shift and how it may lead to a mutation.

Verified step by step guidance

1. Understand that a tautomeric shift is a chemical reaction that involves the transfer of a hydrogen atom and a change in the location of a double bond within a molecule, often affecting nucleic acids like DNA.
2. Recognize that in DNA, the bases (adenine, thymine, cytosine, and guanine) can exist in different tautomeric forms, which are structural isomers differing in the position of protons and electrons.
3. Identify that during DNA replication, if a base is in its rare tautomeric form, it may pair incorrectly with the wrong complementary base (e.g., a rare tautomer of cytosine might pair with adenine instead of guanine).
4. Acknowledge that this mispairing can lead to a point mutation if the tautomeric form reverts to its common form after replication, resulting in a permanent change in the DNA sequence.
5. Consider that such mutations can have various effects, ranging from benign to causing diseases, depending on where in the genome they occur and how they affect gene function.

Key Concepts

Tautomeric Shift

A tautomeric shift refers to the rearrangement of hydrogen atoms and double bonds in a molecule, resulting in the formation of isomers known as tautomers. In nucleic acids, this shift can occur in the bases, such as adenine and guanine, altering their hydrogen bonding properties. This change can lead to incorrect base pairing during DNA replication, as the tautomer may pair with a different base than intended.

Base Pairing and DNA Replication

Base pairing is the specific hydrogen bonding between nucleobases in DNA, where adenine pairs with thymine and cytosine pairs with guanine. During DNA replication, the accuracy of base pairing is crucial for maintaining genetic fidelity. A tautomeric shift can cause a base to mispair with an incorrect partner, leading to the incorporation of an erroneous nucleotide into the newly synthesized DNA strand.

Mutation

A mutation is a permanent alteration in the DNA sequence that can result from various factors, including errors during DNA replication. When a tautomeric shift leads to mispairing, the resulting incorrect base can be retained after DNA replication, creating a mutation. These mutations can have various effects, ranging from benign to harmful, depending on their location and nature within the genome.