Skip to main content
Back

Mendelian Genetics and Probability in Inheritance

Control buttons has been changed to "navigation" mode.
1/20
  • What is a gene?

    A gene is a discrete heritable unit that determines a specific characteristic in an organism.

  • What are alleles?

    Alleles are alternative versions of a gene that account for variations in inherited characters.

  • What is the locus of a gene?

    The locus is the specific physical location of a gene on a chromosome.

  • Explain Mendel's Law of Segregation.

    The two alleles for a heritable character separate during gamete formation, so each gamete carries only one allele.

  • What is the difference between homozygous and heterozygous genotypes?

    Homozygous means having two identical alleles; heterozygous means having two different alleles for a gene.

  • Define genotype and phenotype.

    Genotype is the genetic makeup of an organism; phenotype is the observable traits or appearance.

  • What is a testcross?

    A testcross is a cross between an organism with an unknown genotype and a homozygous recessive organism to determine the unknown genotype.

  • What is Mendel's Law of Independent Assortment?

    Allele pairs for different genes segregate independently during gamete formation, applying to genes on different chromosomes or far apart on the same chromosome.

  • What phenotypic ratio results from a monohybrid cross of heterozygotes?

    The typical phenotypic ratio is 3:1 dominant to recessive traits in the F2 generation.

  • What phenotypic ratio results from a dihybrid cross of heterozygotes?

    The phenotypic ratio is 9:3:3:1 for the four possible trait combinations in the F2 generation.

  • How do you use a Punnett square?

    A Punnett square predicts the allele composition and genotype ratios of offspring from parents with known genotypes.

  • What is the blending hypothesis and why is it incorrect?

    The blending hypothesis suggests genetic material blends in offspring, but Mendel showed inheritance is particulate with discrete units (genes).

  • What is the particulate hypothesis?

    The particulate hypothesis states that genes are discrete units passed unchanged from parents to offspring.

  • What is the dominant allele?

    The dominant allele determines the organism's appearance when present, masking the recessive allele.

  • What is the recessive allele?

    The recessive allele has no noticeable effect on appearance when paired with a dominant allele.

  • How does Mendel's use of pea plants benefit genetic studies?

    Pea plants are easy to grow, have true-breeding strains, controlled mating, short generation time, and distinct traits with two forms.

  • What is the significance of Mendel's 3:1 ratio?

    The 3:1 ratio in the F2 generation supports the existence of dominant and recessive alleles and segregation of alleles.

  • How do you calculate the probability of independent genetic events?

    Use the multiplication rule: multiply the probabilities of each independent event occurring together.

  • How do you calculate the probability of mutually exclusive genetic events?

    Use the addition rule: add the probabilities of each mutually exclusive event occurring.

  • Why is sample size important in Mendel's experiments?

    Larger sample sizes yield results closer to predicted ratios, increasing the reliability of genetic conclusions.