Inheritance

Inheritance Notes

Inheriting DNA

• Genes are hereditary units passed down from generation to generation.

• Alleles and Phenotypes:

  • The combination of alleles inherited (genotype) influences the observable traits (phenotype).

  • Environmental factors can also affect gene expression.

• Genes and Chromosomes:

  • A gene is a DNA section coding for a protein, located on chromosomes

• Homozygous vs. Heterozygous:

  • Homozygous: Same alleles (e.g., BB or bb).

  • Heterozygous: Different alleles (e.g., Bb).

• Dominant Traits:

  • Dominant traits do not skip generations; at least one parent must express the trait.

• Recessive Traits:

  • Recessive traits may not be expressed in parents (heterozygous).

Reproduction

• Reproductive Strategies:

  • Asexual reproduction creates identical offspring.

  • Sexual reproduction involves two individuals, enhancing genetic diversity.

• Meiosis:

  • Process of gamete formation (eggs and sperm in animals; pollen and ova in plants).

• Gametes:

  • Gametes contain half the DNA of somatic cells (one copy of each chromosome).

• In Vitro Fertilization: a method of fertilization outside the body.

• Genetic Variation in Gametes:

  • Meiosis results in genetically diverse gametes.

• Fertilization:

  • Fusion of two gametes forms a zygote, the first cell of a new individual.

Mutations

• Changes in DNA sequence can create new alleles or alter existing ones.

• Somatic mutations affect body cells; germline mutations affect gametes

• Types of Mutations:

  • Beneficial (e.g., malaria resistance).

  • Neutral (e.g., ability to smell ants).

  • Harmful (e.g., cystic fibrosis).

Predicting Genetic Outcomes

• Allele Representation:

  • Dominant alleles are represented by capital letters; recessive by lowercase

• Definitions:

  • Phenotype: Observable traits.

  • Genotype: Combination of alleles

• Punnett Squares:

  • Tool for predicting offspring genotypes/phenotypes based on parental genotypes.