key terms Flashcards
define chromosome
a long section of DNA coiled around histones that is made up of many genes
define heterozygous
a pair of homologous chromosomes carrying two different alleles for a single gene
define gene
a section of DNA which codes for a particular protein
define locus
the position of a gene on a chromosome
define allele
an alternative version of a gene
define genotype
the combination of alleles that an organism has for a gene
define phenotype
expression of genes and its interaction with the environment
define dominant
allele that is always expressed if present
define recessive
allele that is only expressed if there is no dominant allele present
what is monogenic inheritance
inheritance of a characteristic that is controlled by only 1 gene
- eg. inheritance of cystic fibrosis
define homozygous
a pair of homologous chromosomes that carry the same alleles for a gene
define codominant
both alleles are equally dominant and both are expressed in phenotype
define multiple alleles
more than 2 alleles for a single gene
define sex linkage
gene whose locus is on X chromosome
define autosomal linkage
genes located on same chromosome (not sex chromosomes)
define epistasis
one gene modifies or masks the expression of a different gene at a different locus
define monohybrid
genetic inheritance cross of a characteristic determined by one gene
define dihybrid
genetic inheritance cross for a characteristic determined by two genes
define gene pool
all the alleles of all the genes within a population at one time
define population
all the individuals of a species in one area at one time
define allele frequency
the proportion of an allele within the gene pool
