Heredity

FUNDAMENTALS OF HEREDITY

• Heredity: Passing traits from one generation to the next.

• Traits: Specific characteristics (e.g., hair color, eye color) that affect appearance and body function.

PEDIGREES

• Pedigree: Diagram showing trait history across generations.

• Indicates patterns, identifies genetic disorder carriers, and aids in genetic counseling.

• Representation Rules:

  • Females: Circles, Males: Squares

  • Connections: Lines between mother and father, offspring ordered from oldest to youngest

• Shading:

  • Half-shaded: Carrier, Full-shaded: Expresses the trait.

TRAIT CLASSIFICATION

• Types:

  • Dominant Traits: Always expressed (e.g., brown hair, brown eyes).

  • Recessive Traits: Covered or less visible (e.g., blonde hair, blue eyes).

GENES AND ALLELES

• Genes: Units of heredity; one inherited from each parent.

• Alleles: Gene pairs from both parents.

• Chromosomes: Structures carrying genetic information.

GENE REPRESENTATION

• Dominant traits denoted by uppercase letter (e.g., R for right-handedness).

• Recessive traits denoted by lowercase letter (e.g., r for left-handedness).

TRAIT EXPRESSION

• Genotype: Genetic makeup; can be homozygous (pure) or heterozygous (mixed).

• Phenotype: Observable traits.

PUNNETT SQUARE

• Tool for predicting offspring gene combinations.

• Visual representation shows possible genotypes and phenotypes based on parental traits.

INCOMPLETE DOMINANCE

• Occurs when neither trait is fully dominant; results in a "mixed" phenotype.

• Example: Red x White flowers yield Pink.

ROLE OF DNA

• DNA: Instruction set within cells, making up genes and determining traits.

• Base combinations (Adenine, Thymine, Cytosine, Guanine) create different proteins affecting traits.

GENETIC VARIABILITY

• Offspring inherit unique combinations of parental DNA, leading to individual diversity.

GENETICS AND DISEASE

• Example: Sickle-cell Anemia is a genetic disease caused by incomplete dominance affecting red blood cell shape.