mendel and the gene idea

Blending Hypothesis

The idea that genetic material mixes (like blue + yellow = green); predicts uniform populations and cannot explain skipped generations

Gregor Mendel

Augustinian monk and founder of genetics (1822–1884)

Particulate Hypothesis

Parents pass discrete heritable units (genes) that retain identity

Christian Doppler

Physicist who influenced Mendel’s use of math

Character

A heritable feature that varies among individuals

Trait

A variant of a character

True Breeding

Produces identical offspring when self-pollinating

Hybridization

Mating of two true-breeding varieties

P Generation

Parental generation in a genetic cross

F1 Generation

First offspring generation (heterozygous)

F2 Generation

Offspring of F1 generation

Law of Segregation

Two alleles separate during gamete formation

Law of Independent Assortment

Alleles assort independently if on different chromosomes

Dominant

Trait that masks another

Recessive

Trait masked by dominant allele

Homozygous

Two identical alleles

Heterozygous

Two different alleles

Phenotype

Observable traits

Genotype

Genetic makeup

Testcross

Cross with homozygous recessive to determine genotype

Punnett Square

Chart predicting allele combinations

Incomplete Dominance

Intermediate phenotype

Codominance

Both alleles fully expressed

Polygenic Inheritance

Multiple genes affect one trait

Pedigree

Family tree of traits

Cystic Fibrosis

Recessive disorder causing mucus buildup

Sickle Cell Disease

Recessive blood disorder

Huntington’s Disease

Dominant neurodegenerative disorder

Amniocentesis

Prenatal test using amniotic fluid

Karyotype

Chromosome image set