Inheritance

15.1 What is Inheritance?

• Definition: Passing of traits from parents to offspring through genes.
• Genes: Sequences of DNA that code for proteins.
• Chromosomes: Structures that carry genes.

15.2 Mendelian Inheritance

• Dominant Alleles: Expressed in the presence of another allele.
• Recessive Alleles: Expressed only if two copies are present.
• Mendel’s Laws:
  1. Law of Segregation: Alleles separate during gamete formation.
  2. Law of Independent Assortment: Genes for different traits are inherited independently.

15.3 Genotype and Phenotype

• Genotype: Genetic makeup (e.g., Aa, AA).
• Phenotype: Observable traits (e.g., brown eyes).

15.4 Punnett Squares

• Tool to predict genetic inheritance.
• Example: Cross of two heterozygous pea plants (Aa x Aa) produces 25% AA, 50% Aa, 25% aa.

15.5 Sex-Linked Inheritance

• Traits linked to X chromosome (e.g., hemophilia).
• More common in males (XY) than females (XX).

15.6 Mutation

• Definition: Change in DNA sequence.
• Types:
  1. Point Mutation: Change in a single nucleotide.
  2. Frameshift Mutation: Insertion or deletion of a base.

15.7 Genetic Disorders

• Cystic Fibrosis: Recessive disorder, affects lungs and digestion.
• Sickle Cell Anemia: Recessive disorder, causes abnormal hemoglobin.