3:4

phenotype

form of a trait an individual has (blue eyes, brown hair)

gene

individual unit of genetic information

old and new definition of gene

one gene- one trait

one gene- one protein

allele

a specific version of a gene, different alleles for the same gene result in slightly different versions of a protein

adults have __ copies of each human chromosome

2; one from each of their parents

chromosomes of the same type are called

homologous chromosomes

humans have __ homologous pairs of chromosomes

23

we have ___ alleles for every gene

2, because we have two chromosomes of each type

genotype

the collection of alleles an individual has for a specific gene (Bb, aa)

homozygous genotype

both alleles are the same

heterozygous genotype

both alleles are different

we often refer individual with heterozygous genotype as

carriers because they carry the recessive allele but don’t show that phenotype

gametes have one copy of each chromosome, so each gamete will only have

one of the two alleles the parent has for every gene