BIO-110: Mendel and Modern Genetics

Gregor Mendel

An Austrian monk who used pea plants to test theories of trait inheritance and was considered the father of modern genetics

Genetics

The study of how traits are inherited

Traits

The characteristics that vary between individuals; can be binary or on a continuous spectrum

Cross

A single breeding of different individuals

Hybrid

An individual w/ different traits from two crossed individuals

Principle of Segregation

One trait particle (allele) is donated by each parent to their offspring, which are segregated in the gametes of the offspring so each gamete only carries one allele

Genotype

The combination of alleles carried by a specific individual (TT, Tt, tt)

Phenotype

The traits themselves (hair color, eye color, etc.)

Homozygous

When alleles are the same (BB or bb)

Heterozygous

When alleles are different from each other (Bb)

Principle of Independent Assortment

Different gene alleles are inherited independent of each other

Multiple allelism

A gene w/ more than two possible alleles

Codominance

The simultaneous expression of the phenotype of each allele present, rather than a dominant-recessive relationship

Incomplete dominance

Describes the phenotype of a heterozygote that is a mix the dominant and recessive phenotypes

Pleiotropy

When a single influences more than one trait

Polygenic inheritance

Where many genes all contribute to one trait

Sex-linked genes

Genes on sex chromosomes; X-linked on the X chromosome and Y-linked on the Y chromosome

X-linked disorders

Caused by homozygosity for a recessive allele are much more common in men because they only have one X chromosome