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OCR A Biology

Dihybrid Inheritance Diff Seeds Hetero Crosses Genes E.G

Dihybrid crosses analyze the inheritance of two genes on different chromosomes, showing that heterozygous parents (e.g., YyRr) produce four types of gametes, typically leading to a 9:3:3:1 phenotypic ratio in offspring.

Dihybrid crosses examine the inheritance of two genes located on different chromosomes. Gametes from parents heterozygous for both genes (e.g., YyRr) produce four possible allele combinations (YR, Yr, yR, yr). Crossing two such parents typically results in a 9:3:3:1 phenotypic ratio.

Front Dihybrid inheritance and crosses
Back
  • Dihybrid inheritance
    • lots of genes inherited, and dihybrid crosses show inheritance of 2 genes on diff chromosomes
  • Dihybrid cross
    • shows inheritance of 2 diff characteristics caused by 2 genes, so 4 alleles shown at each stage (2 for each characteristic)
    • e.g pea plants yellow(Y)/green(y) and round(R)/wrinkled(r)
    • genotype, watch out for homo/heterozygous, e.g homo yellow round seeds genotype is YYRR, but hetero yellow round seeds is YyRr, homo green wrinkled seeds is yyrr
    • with the homo, gametes combos are just YY and RR, or yy and rr, but hetero (YyRr) gametes are the 4 diff combos (YR,Yr,yR,yr), so use all 4 lined up at top/side of cross against the other genotype (2 hetero genotypes result in 9;3;3;1 ratio

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