GeneticsLesson 3 of 3 in the course Mendel's Experiments and Heredity

Mendelian Inheritance, Linkage, and Gene Interactions

5 flashcards · 4 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson introduces Mendel’s idea that inheritance is based on discrete factors, now called genes and alleles. It explains how dominant and recessive alleles behave and why allele pairs separate when gametes form.

Mendel crossed pea plants with contrasting traits and observed that a trait hidden in the first generation could reappear in the second. For example, a recessive trait absent from the F₁ generation reappeared in the F₂ generation. This pattern suggested that hereditary information did not blend into an intermediate form. Instead, it was passed as discrete units.

All flashcards

Allele
One of the alternative forms of a gene.
Law of segregation
Paired alleles separate during gamete formation, so each gamete receives one allele.
Crossing over
Exchange of chromosome segments between homologous chromosomes that can create new allele combinations.
Product rule
Multiply probabilities to find the chance that independent events occur together.
Epistasis
An interaction in which one gene masks or modifies another gene’s phenotypic effect.

Quiz questions

  1. When does the law of independent assortment apply to two genes?Answer: When the genes assort independently, their alleles enter gametes independently.
  2. In the cross AABb×AABbAABb \times AABb, how many heterozygous gene pairs are counted as nn?Answer: n=1n=1, because only the BB locus is heterozygous.
  3. In a YyRr×YyRrYyRr \times YyRr cross with independent assortment and complete dominance, what is the probability of round, yellow offspring?Answer: 9/169/16
  4. Why do larger offspring samples generally give observed proportions closer to expected genetic ratios?Answer: Chance variation has less influence on proportions in larger samples.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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