Early Genetics Research

This page discusses the foundational work in genetics from the 19th and 20th centuries.

Key points covered:

• A scientist in the mid-19th century studied inheritance in pea plants, laying the groundwork for modern genetics
• In the mid-20th century, scientists identified the chemical substance that makes up genetic material

The page includes multiple choice questions asking students to identify:

1. The name of the scientist who studied pea plant inheritance (Gregor Mendel)
2. The chemical substance that makes up genetic material (DNA)

Highlight: Gregor Mendel's work with pea plants in the mid-19th century was the beginning of our modern understanding of genetics.

Vocabulary: DNA (deoxyribonucleic acid) is the chemical substance that makes up genetic material, identified by scientists in the mid-20th century.

Punnett Squares and Inheritance Ratios

This page demonstrates the use of Punnett squares to predict offspring genotypes and phenotypes.

Key concepts covered:

• Using T for the dominant tall allele and t for the recessive short allele in pea plants
• Completing a Punnett square for a cross between two heterozygous tall plants (Tt x Tt)
• Identifying homozygous offspring in the Punnett square
• Calculating the ratio of tall to short plants in the offspring

The page includes practice problems for students to complete a Punnett square and determine offspring ratios.

Example: A completed Punnett square for Tt x Tt shows: TT, Tt, Tt, tt

Highlight: The ratio of tall to short plants in this cross is 3:1.

Mendel's Flower Color Experiment

This page describes one of Gregor Mendel's original experiments with pea plant flower color.

Key points:

• Mendel crossed pure-breeding red-flowering pea plants with pure-breeding white-flowering plants
• The first generation (F₁) all had red flowers
• Mendel then self-pollinated the F₁ plants
• The second generation (F₂) resulted in 705 red-flowering plants and 224 white-flowering plants

The page includes questions about:

• Identifying the recessive allele (white)
• Drawing a genetic diagram for the F₁ generation
• Explaining why Mendel used self-pollination

Vocabulary: F₁ refers to the first filial generation of offspring in a genetic cross.

Example: A genetic diagram for the F₁ generation cross: RR x rr → Rr (all red-flowering)

Review of Mendel's Experiments

This page provides a comprehensive review of Gregor Mendel's experiments and their significance in the field of genetics.

Key points:

• Overview of Mendel's pea plant experiments
• The importance of Mendel's use of pure-breeding lines
• How Mendel's work laid the foundation for modern genetics

The page includes questions prompting students to:

• Summarize Mendel's key findings
• Explain the significance of his experimental approach
• Connect Mendel's work to current understanding of genetics

Quote: "Mendel's work was the beginning of our modern understanding of genetics."

Highlight: Mendel's use of mathematical ratios to describe inheritance patterns was revolutionary for his time.