PERSILANGAN MONOHIBRID VID 2 PERTEMUAN 8

Summary

This educational video explains monohybrid crosses in genetics, covering both complete dominance and incomplete dominance inheritance patterns. Using the example of red and white roses, the video explores how dominant and recessive traits are passed down. In complete dominance, red flowers dominate, resulting in a 3:1 phenotypic ratio in the F2 generation. In incomplete dominance, the F1 generation shows pink roses, and the F2 generation follows a 1:2:1 genotypic and phenotypic ratio. The video provides clear examples and calculations to demonstrate how these inheritance patterns work in Mendelian genetics.

Takeaways

• 😀 Monohybrid cross is a genetic cross involving organisms with a single differing trait.
• 😀 The two types of monohybrid crosses are complete dominance and incomplete dominance (intermediate).
• 😀 In complete dominance, the dominant allele completely masks the recessive allele in the phenotype.
• 😀 An example of complete dominance is crossing pure-bred red roses (MM) with pure-bred white roses (mm), which results in 100% red roses (Mm) in the F1 generation.
• 😀 In the F2 generation, the genotype ratio for a monohybrid cross with complete dominance is 1:2:1 (MM:Mm:mm), while the phenotype ratio is 3:1 (red:white).
• 😀 In incomplete dominance, the heterozygous genotype results in an intermediate phenotype, such as pink roses from a cross between red and white roses.
• 😀 In a monohybrid cross with incomplete dominance, the F1 generation consists of 100% pink roses (Mm).
• 😀 When the F1 generation (pink roses) is crossed with itself, the F2 generation shows a genotype ratio of 1:2:1 (MM:Mm:mm) and a phenotype ratio of 1:2:1 (red:pink:white).
• 😀 Incomplete dominance results in blending of traits in the heterozygous state, unlike complete dominance where the dominant trait fully expresses itself.
• 😀 The monohybrid cross examples show how the genotypic and phenotypic ratios help determine the inheritance patterns of traits.
• 😀 Understanding monohybrid crosses, whether in complete or incomplete dominance, is essential for predicting offspring traits and genetic outcomes.

Q & A

What is the main topic of the video?

The main topic of the video is monohybrid cross, specifically focusing on full dominance and partial dominance (intermediate dominance).

What is a monohybrid cross?

A monohybrid cross is a genetic cross that involves a single trait and examines the inheritance of one gene with two alleles, one dominant and one recessive.

What is the difference between full dominance and partial dominance in monohybrid crosses?

Full dominance occurs when the dominant allele completely masks the effect of the recessive allele in the phenotype. In partial dominance (intermediate dominance), the heterozygous genotype results in a phenotype that is a blend of both the dominant and recessive traits.

Can you explain the example of the full dominance monohybrid cross with red and white roses?

In the example of full dominance, a red rose (genotype MM) is crossed with a white rose (genotype mm). The offspring (F1) will all have the genotype Mm and display the dominant red phenotype.

What is the phenotype and genotype of the F1 generation in a full dominance monohybrid cross?

In the F1 generation, the phenotype is 100% red roses, and the genotype is 100% heterozygous (Mm).

How are the F2 generation genotypes and phenotypes determined in a full dominance monohybrid cross?

When F1 individuals (Mm) are crossed with each other, the F2 generation can have three genotypes: MM, Mm, and mm. The phenotypes will be 75% red (MM or Mm) and 25% white (mm).

What is the genotypic and phenotypic ratio in the F2 generation of a full dominance monohybrid cross?

The genotypic ratio in F2 is 1 MM : 2 Mm : 1 mm, and the phenotypic ratio is 3 red : 1 white.

How does intermediate dominance differ from full dominance in terms of phenotype expression?

In intermediate dominance, the heterozygous genotype (Mm) results in a phenotype that is a blend of the two parental traits, such as pink flowers from a red (MM) and white (mm) rose cross.

What happens when two F1 offspring with intermediate dominance are crossed?

When two F1 individuals with the genotype Mm are crossed, the F2 generation will have the following genotypes: MM, Mm, and mm. The phenotypes will be 25% red, 50% pink, and 25% white.

What is the genotypic and phenotypic ratio in the F2 generation of a partial dominance monohybrid cross?

The genotypic ratio in the F2 generation of a partial dominance monohybrid cross is 1 MM : 2 Mm : 1 mm, and the phenotypic ratio is 1 red : 2 pink : 1 white.