BIO genetics and evolution Flashcards
Definition of dominant
an allele that is always expressed in the phenotype
definition of recessive
an allele that is only expressed if no dominant allele is present
Definition of genotype
genetic composition of an organism(which two alleles they have for a gene)
definition of phenotype
characteristic of an organism due to expression of genotype and environment
Definition of gene
small section of DNA which codes for a polypeptide
Definition of allele
alternative form of a gene
what is dihybrid crosses?
genetic cross where inheritance of two genes is considered at same time
in a dihybrid cross, both the parents are heterozygous so what would the ratio be normally and if not why?
9:3:3:1 unless autosomal linkage or crossing over in meiosis
what does crossing over result in?
new combination of alleles in gametes
what is autosomal linkage?
when 2 genes are located on same chromosome not x or y
if you do not observe the ratio that you expected what does this mean?
crossing over has occurred
what does crossing over in meiosis do?
new combination of alleles in gametes
