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Mendel's Laws of Segregation and Independent Assortment with Crosses

Monohybrid and dihybrid crosses, phenotypic and genotypic ratios, complete and incomplete dominance, and exceptions for biology and genetics exam preparation.

9 cards· by GuruOwl

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  1. 01
    Mendel's law of segregation states that the two alleles for each gene separate during gamete formation so that each gamete receives only one allele.
    This occurs specifically during the separation of homologous chromosomes in meiosis I.
    Flashify::MendelianGenetics::Segregation
  2. 02
    In a monohybrid cross of pure-breeding parents (AA x aa), the F2 generation displays a phenotypic ratio of 3:1 and a genotypic ratio of 1:2:1.
    The 3:1 ratio represents three dominant phenotypes to one recessive phenotype.
    Flashify::MendelianGenetics::MonohybridCross
  3. 03
    What is the purpose and setup of a genetic test cross?
    Crossing a dominant-phenotype individual with a homozygous recessive individual (aa) to reveal the unknown parent's genotype.
    If the parent is heterozygous, the offspring ratio will be 1:1.
    Flashify::MendelianGenetics::TestCross
  4. 04
    The law of independent assortment states that alleles of different genes assort independently of one another during gamete formation.
    This principle only applies if the genes are on different chromosomes or are very far apart on the same chromosome.
    Flashify::MendelianGenetics::IndependentAssortment
  5. 05
    A dihybrid cross (AaBb x AaBb) results in a classic F2 phenotypic ratio of 9:3:3:1.
    This ratio represents 9 (both dominant), 3 (dominant A/recessive b), 3 (recessive a/dominant B), and 1 (both recessive).
    Flashify::MendelianGenetics::DihybridCross
  6. 06
    In incomplete dominance, the heterozygote displays a blended intermediate phenotype, whereas in codominance, both alleles are fully and simultaneously expressed.
    Example: Pink flowers (incomplete) vs. AB blood type (codominance).
    Flashify::MendelianGenetics::DominancePatterns
  7. 07
    Pleiotropy occurs when a single gene affects multiple phenotypic traits, while epistasis occurs when one gene masks or modifies the expression of another.
    Epistasis typically alters the expected 9:3:3:1 dihybrid ratio to variations like 9:3:4 or 12:3:1.
    Flashify::MendelianGenetics::GeneInteractions
  8. 08
    Polygenic inheritance involves multiple genes contributing additively to a single trait, resulting in continuous variation (e.g., height).
    These traits typically follow a bell-curve distribution in a population.
    Flashify::MendelianGenetics::PolygenicInheritance
  9. 09
    Genetic linkage violates the law of independent assortment because genes are located close together on the same chromosome.
    Recombination frequency is used to measure the map distance between linked genes.
    Flashify::MendelianGenetics::Linkage