BIO 1107 Ch 11: Mendel's Principles of Heredity and Genetics

Particulate hypothesis

Parents pass discrete heritable units (genes) to offspring.

Character

Heritable feature that varies among individuals.

Trait

Variant of a character, like flower color.

True-breeding

Plants produce offspring of the same variety.

Law of Segregation

Alleles separate during gamete formation.

Alleles

Alternative versions of a gene at a locus.

Dominant allele

Determines appearance when present with recessive allele.

Recessive allele

Has no noticeable effect on appearance when paired.

Punnett square

Tool to predict offspring genotype combinations.

Monohybrid cross

Cross between two heterozygous parents for one character.

Dihybrid cross

Cross between parents differing in two characters.

Law of Independent Assortment

Alleles segregate independently during gamete formation.

Probability laws

Govern Mendelian inheritance patterns.

Complete dominance

Heterozygote phenotype identical to dominant homozygote.

Incomplete dominance

F1 hybrids show intermediate phenotype between parents.

Codominance

Both dominant alleles affect phenotype distinctly.

Dominant allele frequency

Dominant alleles not always more common than recessive.

Multiple alleles

Genes exist in more than two allelic forms.

ABO blood group

Determined by three alleles: IA, IB, and i.

Polygenic inheritance

Multiple genes contribute to a single phenotype.

Quantitative characters

Traits vary along a continuum in populations.

Phenotype

Organism's observable traits and characteristics.

Genotype

Organism's genetic makeup influencing phenotype.

Environmental influence

Phenotype reflects unique environmental history.

Mendelian patterns

Many human traits follow simple inheritance rules.

Genetic research limitations

Humans have long generation times and few offspring.