Genetic pattern of inheritance

• The genetic pattern of inheritance is a fundamental concept in genetics that explains how traits and characteristics are passed from parents to their offspring.

• These patterns are governed by the laws discovered through the work of Gregor Mendel, as well as more complex genetic interactions that do not follow Mendelian principles.

Here's a structured overview of the main patterns of inheritance:

Mendelian Inheritance

Overview:

• Based on Gregor Mendel's studies on pea plants.

• Involves traits controlled by single genes on autosomal chromosomes.

Key Laws:

1. Law of Segregation:

• Individuals possess two alleles for each gene, one inherited from each parent.

• These alleles segregate during gamete formation, ensuring each gamete carries only one allele for each gene.

1. Law of Independent Assortment:

• The alleles of different genes assort independently during gamete formation, leading to various allele combinations in the offspring.

Modes of Inheritance:

1. Autosomal Dominant:

• A single copy of the dominant allele is enough to express the trait.

• Offspring have a 50% chance of inheriting the trait if one parent is affected.

1. Autosomal Recessive:

• Two copies of the recessive allele are needed to express the trait.

• There's a 25% chance that offspring will express the trait if both parents are carriers.

1. X-Linked Dominant:

• Dominant allele is on the X chromosome.

• Males (XY) have a 50% chance of inheriting from an affected mother; females (XX) have a 50% chance if the father is affected, and up to a 75% chance if both parents are affected.

1. X-Linked Recessive:

• Recessive allele is on the X chromosome.

• Males are more likely to express the trait, while females need two copies of the allele.

Non-Mendelian Inheritance

Overview:

• Represents more complex genetic interactions that do not adhere to Mendel's laws.

Types:

1. Codominance:

• Both alleles are equally expressed, leading to a phenotype that shows both traits distinctly.

1. Incomplete Dominance:

• Neither allele is dominant, resulting in a blended phenotype.

1. Polygenic Inheritance:

• Multiple genes influence a single trait, producing a range of phenotypes (e.g., skin color, height).

1. Epistasis:

• The expression of one gene is affected by another gene, altering phenotypic outcomes.

1. Mitochondrial Inheritance:

• Traits are passed through maternally inherited mitochondrial DNA, not through nuclear DNA.

1. Genomic Imprinting:

• Gene expression varies depending on whether the gene is inherited from the mother or father, influenced by epigenetic modifications.