genetics Flashcards
Locus
– site of a gene in the chromosome
Alleles
– different forms of a gene
– same loci on homologous chromosomes
Mendel’s Principle of Segregation
During meiosis
– paired alleles separate
Gametes (haploid)
– have one allele per locus
what determines how chromosomes
are distributed into haploid cells
Random orientation of pairs of
homologous chromosomes in metaphase I
of meiosis
how do you figure out unknown genotype
Test Cross
homozygous recessive
Linked Genes
groups of genes on the same chromosome (close)
– tend to be inherited together (linkage)
examples of linked genes
dark skin curly hair
freckles red hair
Pleiotropy
ability of one gene to have several effects on different characters
Incomplete dominance
alleles are “combined” that show a different phenotype
Codominance
heterozygote expresses phenotypes of both
homozygotes at the same time
Epistasis
allele of one locus can mask the
expression of alleles of a different locus
Polygenic Inheritance
Multiple independent pairs of genes may
have similar and additive effects on the
phenotype
example of Polygenic Inheritance
skin colour
Norm of Reaction
range of phenotypic possibilities
– from a single genotype
– under different environmental conditions
Norm of Reaction examples
height, soil acidity in plants
