Genetics week 5

Somatic vs. Germline Mutations

• Somatic mutations occur in non-reproductive body cells and are not heritable.
• Germline mutations arise in reproductive cells and can be passed to future generations.
• Germline mutations impact the entire organism while somatic mutations typically affect only the individual.
• Examples of somatic mutations include those leading to lung or skin cancer, whereas germline mutations can cause conditions like sickle cell disease or cystic fibrosis.

Spontaneous vs. Induced Mutations

• Spontaneous mutations happen naturally without external factors and contribute to genetic diversity.
• Induced mutations result from exposure to mutagens, such as chemicals or radiation, influencing environmental factors.
• Induced mutations are important for research in genetics and molecular biology.
• Both spontaneous and induced mutations play roles in evolution, genetics, and medical advancements.

Back Mutations vs. Suppressor Mutations

• Back mutations restore the original DNA sequence, reverting phenotype to its initial state.
• Suppressor mutations do not change the original sequence but compensate for the effects of the original mutation.
• Back mutations occur at the same location as the original mutation, whereas suppressor mutations can occur at different sites, within the same gene or another gene.
• Understanding these types of mutations aids in genetic analysis and treatment of genetic disorders.

Phenylketonuria (PKU) and Albinism

• PKU results from mutations affecting the metabolic pathway of phenylalanine, leading to its accumulation and brain damage if untreated.
• Albinism is caused by mutations in the tyrosinase gene, resulting in the absence of melanin production.
• A lack of tyrosinase affects the conversion of phenylalanine to tyrosine, impacting pigmentation in individuals with albinism.

Sickle Cell Anemia

• Sickle cell anemia is caused by a point mutation in the HBB gene on chromosome 11, responsible for the beta-globin subunit of hemoglobin.
• A single nucleotide alteration changes adenine to thymine, resulting in a codon shift from GAG to GTG.
• This mutation replaces glutamic acid with valine at the sixth position of the beta-globin chain.
• The abnormal hemoglobin causes red blood cells to become sickle-shaped under low oxygen conditions, leading to reduced flexibility and impaired blood flow.
• Symptoms of sickle cell anemia include pain crises, organ damage, and increased infection risk due to altered hemoglobin structure and function.