2 U4 AOS2 - Types of Mutations

Central Dogma

• DNA is transcribed into RNA, which is then translated into protein.
• Mutations in DNA can affect RNA sequences and ultimately protein production.

Point Mutations

• One DNA base is replaced with another.
• Example: A thymine base is replaced with an adenine base.

Frame-Shift Mutations

• A base is added or removed from the DNA sequence.
• Changes the reading frame of the RNA, affecting multiple codons and amino acids.
• Has more significant effects on the final protein than point mutations.

Non-sense Mutations

• A genetic mutation that leads to the RNA sequence becoming a stop codon instead, truncating the protein.

Missense Mutations

• A genetic mutation that changes an amino acid from one to another.

Silent Mutations

• Mutation does not affect the protein because different RNA codons can code for the same amino acid.

Conservative Mutations

• The new amino acid is of the same type as the original (e.g., glutamate to aspartate, both acidic).

Nonconservative Mutations

• The new amino acid is of a different type from the original (e.g., serine to phenylalanine).

Sickle Cell Disease Example

• Hemoglobin (Hb) is mutated into a less active form (HbS).
• A single glutamate residue is converted into a valine residue.
• Classified as both a point mutation and a nonconservative missense mutation.

Key Takeaways

• Mutations originate at the DNA level but show effects at the protein level.
• Mutations can be classified by their effects on DNA (point, frame-shift) or protein (missense, non-sense).