Day 15 of 30
Codominance
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Learning Objective
Students will explore codominance through guided practice and application.
In this lesson, we'll explore codominance. Scientific inquiry allows us to investigate and explain natural phenomena.
Genetics is the study of heredity—how traits pass from parents to offspring. Genes are segments of DNA that code for traits; alleles are alternative versions of a gene. Dominant alleles mask recessive alleles when both are present. Genotype is the genetic makeup (e.g., Bb); phenotype is the observable trait (e.g., brown eyes). Homozygous: both alleles identical (BB or bb). Heterozygous: two different alleles (Bb). Punnett squares predict offspring ratios: a Bb × Bb cross gives 1 BB : 2 Bb : 1 bb (3:1 phenotype ratio if B is dominant). Incomplete dominance: heterozygotes show a blend (red + white = pink). Codominance: both alleles expressed simultaneously (AB blood type). Sex-linked traits are on the X chromosome—more common in males (XY). Pedigrees track traits across family generations. A karyotype is an organized image of chromosomes; humans have 46 (23 pairs).
As you work through today's material, pay attention to the examples and try to identify the patterns or strategies being used. This will help you apply these concepts to new problems.
Take notes on key points and make connections to what you've already learned in previous lessons.
To examine systematically through observation and experiment
Observable facts that support or refute a claim
Instructions
Materials Needed
- Lab notebook
- Investigation materials
- Safety equipment if needed
Based on today's lesson, what is one thing you observed or learned?
How could you test or investigate this topic further?
Why is this topic important in the real world?
Teaching Tip
For advanced learners: Encourage deeper analysis and real-world connections. Consider extension activities that allow students to apply codominance to novel situations.