Gene Mutations Alter The Instructions For Building Proteins
Definition
Gene mutation
A gene mutation is a permanent change in the nucleotide sequence of DNA, affecting the structure and function of proteins.
- Gene mutations can be classified into three main types:
- Substitutions
- Insertions
- Deletions.
- Imagine reading a book where a single letter is changed, added, or removed.
- The meaning of the sentence could stay the same, change slightly, or become completely nonsensical.
- This is exactly how gene mutations work.
Substitution Mutations: Swapping One Base for Another
- In substitution mutations, one nucleotide is replaced by another.
- This is like swapping a letter in a word: "cat" becomes "bat."
Since substitution mutations affect only one codon, their impact is often less severe than insertions or deletions.
Insertion Mutations: Adding Extra Bases
- In insertion mutations, one or more nucleotides are added to the DNA sequence.
- This shifts the reading frame of the genetic code, altering every codon downstream of the mutation.
Deletion Mutations: Removing Bases
- Deletion mutations occur when one or more nucleotides are removed from the DNA sequence.
- Like insertions, deletions can cause frameshifts unless the number of deleted bases is a multiple of three.
Frameshift mutations (caused by insertions or deletions) are usually more severe than substitutions because they affect the entire protein sequence downstream of the mutation.
Why Mutations Matter
- Mutations can have a wide range of effects:
- Neutral: Many mutations occur in non-coding regions of DNA or result in silent mutations that do not affect the protein.
- Harmful: Mutations can disrupt protein function, leading to genetic disorders or diseases like cancer.
- Beneficial: Rarely, mutations can improve a protein’s function or confer an advantage, such as resistance to certain diseases.
The CCR5-Δ32 mutation provides resistance to HIV by altering a receptor on immune cells.
Theory of Knowledge- How do you think the randomness of mutations influences the balance between stability and change in living organisms?
- Could this concept apply to other areas, such as technology or society?
- Distinguish between insertion, deletion, and substitution mutations.
- What does a "point mutation" refer to?
- Which type of mutation is most severe?
