Lab 3 Inheritance Flashcards
Gregor Mendel
A European monk who conducted tests on pea plants and identified two important principles of classification.
Law of segregation
Law stating that the units (or genes) for traits appear separately in the (sex cells of) parents and are then reunited in an offspring.
Law of independent assortment
Law stating that the units (or genes) for different traits are sorted (and passed on) independently of one another.
Dominant
A dominant allele masks the effects of other alleles for a trait; may also be used in reference to dominant traits or dominant phenotypes.
Recessive
A recessive allele is masked by a dominant allele for a trait; may also be used in reference to recessive traits or recessive phenotypes.
Genotype
The specific alleles an organism has for a trait.
Homozygous dominant
An organism’s genotype for a trait when it has two dominant alleles for the trait (such as RR).
Homozygous recessive
An organism’s genotype for a trait when it has two recessive alleles for the trait (such as rr).
Heterozygous
An organism’s genotype for a trait when it has one dominant allele and one recessive allele for the trait (such as Rr).
Phenotype
The physical expression of an organism’s genotype for a trait.
Punnett square
The method of diagramming inheritance where parental genotypes are used to estimate the probability of various genotypes in a potential offspring.
Pedigree diagram
The method of diagramming inheritance that shows the phenotypes of individuals from multiple generations in a family.
Mendelian trait
A trait controlled by one gene (although there may be multiple alleles for that one gene).
Genetic locus (loci, plural)
The location of a gene on a chromosome.
Polygenic trait
Polygenic trait
A trait controlled by alleles at multiple genetic loci.
Sex-linked trait
Sex-linked trait
A trait coded for by a gene on the X or Y chromosome (although typically used to refer to traits on the X chromosome).
Antigen (in ABO blood group system)
The cell surface marker found on red blood cells that relates to an individual’s ABO blood type and triggers antibody reactions to a foreign blood antigen.
Color blindness
Color blindness
Limited perception of certain colors, which may be the result of variation in the alleles for color vision.
Codominant
Circumstance where multiple alleles are expressed in the phenotype, without one being clearly dominant over the other.
Antibody
A protein that attacks antigens directly or marks them for attack by other parts of the immune system.
