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Genetics (Ch. 14 & 15) - Coggle Diagram
Genetics (Ch. 14 & 15)
Mendel & the Gene Idea
Characters: heritable feature (ex: flower color) Trait: variant of a character (ex: purple vs. white)
True-breeding: identical offspring when self-pollinating
Hybridization: crossing 2 true-breeding parents
Law of Segregation: Alleles separate during gamete formation. Each gamete gets one allele. 3:1 ratio in F₂ (dominant:recessive)
Alleles: alternative gene versions
Dominant: expressed (P)
Recessive: masked (p)
Homozygous: same alleles (PP or pp)
Heterozygous: different alleles (Pp)
Genotype: genetic makeup
Phenotype: physical appearance
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Probability Rules: Multiplication rule - “and” events. Addition rule - “or” events. Use to predict monohybrid/dihybrid outcomes
Complex Inheritance
Multiple Alleles: More than two alleles
Example: ABO blood group (IA, IB, i)
Pleiotropy: One gene --> multiple phenotypes
Example: sickle-cell affects RBC shape, oxygen transport, organs
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Polygenic Inheritance: Many genes --> one trait
Example: height, skin color
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Recessive Disorders: Carriers = heterozygotes
Examples: cystic fibrosis, albinism, sickle-cell disease
Dominant Disorders: Rare; show even in heterozygotes
Examples: Huntington’s, achondroplasia
Complete dominance: heterozygote = dominant
Incomplete dominance: intermediate phenotype (red × white = pink)
Codominance: both alleles expressed (ex: MN blood group)
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Linkage, Recombination & Gene Mapping
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