Monohybrid cross

🔬 Monohybrid Cross (Genetics 101) 1. What’s a Monohybrid Cross? A monohybrid cross is a mating between two organisms that differ in one specific trait—like pea color: yellow vs. green.

Each organism has two alleles for that gene (one from each parent).

One allele might be dominant (A), the other recessive (a).

2. Parent Genotypes: Example: One parent is AA (dominant trait), the other is aa (recessive trait).

3. The Punnett Square Vibe: A (sperm) A (sperm) a (egg) Aa Aa a (egg) Aa Aa

All F₁ offspring are Aa—they show the dominant phenotype.

4. F₁ Cross (Aa × Aa) — What Happens Next? Punnett square time for F₂ generation:

A (sperm) a (sperm) A (egg) AA Aa a (egg) Aa aa

Genotypes F₂:

1 AA : 2 Aa : 1 aa

Phenotypes:

3 dominant : 1 recessive (3:1 ratio)

5. Key Takeaways Monohybrid = single trait (e.g. seed shape, flower color)

F₁ typically all show dominant trait (if parents are pure-breeding)

F₂ shows classic 3:1 phenotypic ratio

Genotype ratio: 1:2:1 (AA : Aa : aa)

6. Real‑world Example Mendel’s peas:

P generation: Yellow (YY, dominant) × Green (yy, recessive)

F₁: 100% yellow (Yy)

F₂: about 75% yellow, 25% green

7. Visual Summary yaml Copy Edit Parent Genotypes:

   YY (yellow pea) × yy (green pea)

F₁ Generation:

   Yy (all yellow)

F₁ Cross:

   Yy × Yy

F₂ Offspring:

   - YY ⇒ yellow
   - 2 × Yy ⇒ yellow
   - yy ⇒ green

Resulting Phenotype Ratio:

   3 yellow : 1 green

Genotype Ratio:

   1 YY : 2 Yy : 1 yy

8. Why It’s Lit for Science & Biz Life Helps predict inheritance patterns

Basic tool for genetics, breeding, and biotech

Understanding traits = unlocking nature’s code

Monohybrid Cross Media

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  Figure 1: Inheritance pattern of dominant (red) and recessive (white) phenotypes when each parent (1) is homozygous for either the dominant or recessive trait. All members of the F1 generation are heterozygous and share the same dominant phenotype (2), while the F2 generation exhibits a 6:2 ratio of dominant to recessive phenotypes (3).