Genetic Mutations and Human Heredity Principles

Genetic Mutations and Heredity

Mutations: Changes in genetic material.

Types of Genetic Alterations

• Genetic mutations: The alteration affects the chemistry and structure of genes.
• Chromosomal mutations: Alteration affecting chromosome structure.
• Numerical or genomic mutations: Alterations affecting the number of chromosomes.

Causes of Mutations

• Physical mutagenic agents
• Chemical substances
• Biological agents: Viruses

Karyotype and Sex Determination

Karyotype: Chromosomal characteristics of a species.

Sex homogametic / heterogametic: Homogametic individuals produce gametes with the same type of sex chromosome, while heterogametic individuals produce two types of gametes, each carrying a different sex chromosome.

Heredity and Human Variability

Genetic and Environmental Factors

• Genetic differences: Genetic characteristics are heritable and constitute the individual's genotype, which is unique for each individual.
• Environmental factors: These also play a key role in our lives (climate, food, etc.) and produce effects on the phenotype that are not transmittable.

Continuous and Discontinuous Characteristics

Characteristics differ from each other and are categorized into two types: continuous and discontinuous.

Continuous characteristics: These show very little variation, forming differences between individuals that are very small. In most cases, these features involve numerous phenotypes with minimal differences between them, depending on several sets of genes whose effects are additive. This shows that the final result in an individual is a product of the sum of different genes involved.

Discontinuous features: These present few alternatives that are clearly distinguishable from each other.

Blood Groups

• Group A: Has antigen A and produces anti-B antibodies in the plasma.
• Group B: Has antigen B and produces anti-A antibodies in the plasma.
• Group AB: Has antigens A and B and the plasma does not produce anti-A or anti-B antibodies.
• Group O: Does not have these antigens and produces both anti-A and anti-B antibodies in the plasma.

Genetic Disorders and Conditions

• Polydactyly: This is a case of alteration due to dominant alleles. It is an alteration of the allele that controls the number of fingers and toes.
• Albinism: An alteration consisting of recessive alleles. The individual is unable to synthesize melanin, the substance responsible for pigmentation.
• Cystic fibrosis and sickle cell anemia: These are also caused by recessive alleles.
• Hemophilia: The absence of any of the factors intervening in the coagulation of blood.