AP Biology: Cell Division and Genetics

Mitosis vs Meiosis

Cell division is a cornerstone of AP Biology. Understanding the differences between mitosis (for growth and repair) and meiosis (for sexual reproduction) is essential.

Phases of Mitosis

• Prophase: Chromatin condenses; spindle forms

• Metaphase: Chromosomes align at metaphase plate

• Anaphase: Sister chromatids pulled to opposite poles

• Telophase: Nuclear envelope re-forms; cytokinesis begins

Mendelian Genetics

Punnett squares predict offspring ratios. For a monohybrid cross Aa × Aa: 1 AA : 2 Aa : 1 aa (3:1 phenotype ratio). For dihybrid: 9:3:3:1.

Beyond Mendel

• Incomplete dominance: heterozygote shows intermediate phenotype

• Codominance: both alleles fully expressed (e.g. blood type AB)

• Sex-linked traits: genes on X chromosome (e.g. colour blindness)