Patterns of inheritance and Mendel's laws

Heredity

The transmission of traits from one generation to the next.

Genetics

The scientific study of heredity.

Gregor Mendel's arguments in the 1860s?

Parents pass on their offspring discrete 'heritable factors (genes)'. Genes are responsible for inherited traits. Genes retain their individual identities generation after generation.

character

A heritable feature that varies among individuals; a trait is a variant of a character.

hybrids

Offspring of two different purebred varieties; the parental plants are the P generation and their offspring are the F1 generation.

monohybrid cross

A cross where the scientist looks at one trait at a time.

gene variance

The variation in the genetic makeup among individuals.

Mendel's 4 Hypotheses

1. There are alternative versions of genes for variations in inherited characters. 2. An organism inherits two alleles for each character, one from each parent. 3. If two alleles differ, one is dominant, affecting appearance, and the other is recessive, not affecting appearance. 4. A sperm or egg carries only one allele for a character due to segregation during gamete formation.

law of segregation

Each pair of alleles segregates independently during gamete formation.

phenotype

The physical appearance of an organism.

genotype

The genetic makeup of an organism.

gene locus

A specific location of a gene along a chromosome.

dihybrid cross

The mating of parental varieties that differ in two characters.

law of independent assortment?

The law stating that the inheritance of one character does not affect the inheritance of another.

testcross

A mating between an individual with a dominant phenotype (but unknown genotype) and a homozygous recessive individual.

wild-type traits

Traits that appear most often in nature; not necessarily specified by dominant alleles.

rule of multiplication

The probability of a compound event equals the product of the separate probabilities of the independent events.

pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

genetic disorders

Disorders caused by abnormalities in an individual's genetic makeup.

carrier

Any individual who has the recessive allele but appears normal and carries the disorder.