Unit 5: Heredity

Heredity

the transmission of traits from one generation to the next

Variation

demonstrated by the differences in appearance that offspring show from parents and siblings

Genetics

the scientific study of heredity and variation

Genes

the units of heredity and are made up of segments of DNA

Gametes (sperm and eggs)

are the reproductive cells that pass genes on to the next generation

Homologous chromosomes

the two chromosomes in each pair that carry the same genes at the same loci

Meiosis

cell division that creates gametes

Karyotype

an ordered display of the pairs of chromosomes from a cell

Clone

a group of genetically identical individuals from the same parent (from asexual reproduction)

Law of Segregation

when an organism makes gametes, each gamete receives just one gene copy, which is selected randomly

Phenotype

physical appearance

Genotype

genetic makeup (alleles)

Law of independent assortment

states that each pair of alleles segregates independently of any other pair during gamete formation

Incomplete dominance

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties

Codominance

two dominant alleles affect the phenotype in separate, distinguishable ways

Multiple Alleles

when genes have more than two allelic forms

Sex-linked gene

A gene that is located on either sex chromosome

X-linked genes

What genes on the X chromosome are called

Pleiotropy

when most genes have multiple phenotypic effects

Quantitative characters

those that vary in population along a continuum/spectrum

Epistasis

when a gene at one locus alters the phenotypic expression of a gene at a second locus

Pedigree

a family tree that describes the interrelationships of parents and children across generations