Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Apply principles of Mendelian genetics (monohybrid & dihybrid crosses).
• Explain non-Mendelian inheritance patterns.
• Define genetic mutations and their effects.
• Solve genetic problems using Punnett squares and pedigree diagrams.
• Discuss the implications of genetics in human health and agriculture.

Lesson summary

Genetics and inheritance are fundamental to understanding life itself. This week, we delve deeper into these concepts, building on your previous knowledge. Understanding genetics isn't just about biology; it's about understanding the diversity within our own families and communities, and the potential for both inherited diseases and beneficial traits. In South Africa, with its rich genetic diversity and history of diseases like HIV and TB (which interact with the host's genetics), and genetic predispositions to certain diseases, genetics plays a crucial role in healthcare, agriculture, and conservation.

Lesson notes

2.1 Mendelian Genetics: The Foundation Gregor Mendel, often called the "father of genetics," discovered basic inheritance principles by experimenting with pea plants. These principles are the foundation of our understanding of how traits are passed from parents to offspring.

Genes: Units of heredity that determine specific traits. Each individual has two copies of each gene, one inherited from each parent.

Alleles: Different forms of a gene (e.g., allele for tallness and allele for shortness).

Dominant Allele: An allele that masks the expression of the recessive allele when both are present. Represented by a capital letter (e.g., T for tallness).

Recessive Allele: An allele that is only expressed when two copies are present. Represented by a lowercase letter (e.g., t for shortness).

Genotype: The genetic makeup of an individual (e.g., TT, Tt, tt).

Phenotype: The observable characteristics of an individual (e.g., tall, short).

Homozygous: Having two identical alleles for a gene (e.g., TT or tt).

Heterozygous: Having two different alleles for a gene (e.g., Tt).

Monohybrid Cross: A cross involving only one trait (e.g., plant height).

Dihybrid Cross: A cross involving two traits (e.g., plant height and flower color).

Mendel's Laws: Law of Segregation: Allele pairs separate during gamete formation, and each gamete receives only one allele from each pair.

Law of Independent Assortment: Alleles for different traits are sorted independently of one another during gamete formation. (This only applies to genes on different chromosomes.)