DNA Mutations and Their Effects on Protein Structure

This section explores various types of DNA mutations and their impacts on protein structure and function.

Substitution Mutations:

• Occur when one or more bases are substituted in the DNA sequence
• May or may not change the amino acid sequence due to the genetic code's degeneracy
• Missense mutations, a type of substitution, change a single amino acid

Example: Sickle cell anemia is caused by a substitution mutation in the hemoglobin gene, where glutamic acid is replaced with valine, distorting red blood cells.

Silent/Neutral Mutations:

• Occur in non-coding DNA regions
• Changes in protein tertiary structure have minimal effect on the organism

Insertion and Deletion Mutations:

• Insertion: One or more nucleotide pairs are added to the sequence
• Deletion: One or more nucleotide pairs are removed from the sequence
• Both cause frame shifts, altering the amino acid sequence and protein function

Highlight: Frame shifts can dramatically change protein structure and function, potentially leading to significant phenotypic effects.

Types of DNA Mutations (Continued)

This page continues the discussion on DNA mutations, focusing on more complex types and their effects.

Duplication Mutations:

• One or more bases are repeated, causing a frame shift
• Similar effect to insertion mutations

Inversion Mutations:

• A group of bases becomes separated and rejoins in reverse order
• Alters amino acid sequence and protein structure

Translocation Mutations:

• Groups of bases move from one chromosome to another
• Can have significant phenotypic effects due to gene relocation

Example: Chronic myeloid leukemia is caused by a translocation between chromosomes 9 and 22, resulting in a hybrid protein that promotes uncontrolled cell division.

Nonsense Mutations:

• Produce a premature stop codon, leading to a non-functional protein

Example: Duchenne muscular dystrophy is caused by nonsense mutations in the dystrophin gene, affecting muscle cell structure and function.