Mendelian Genetics

each organism contains 2 "factors" for each trait and these factors seperate during gamete formation so each gamete contains only one factor for each trait

(meiosis)

members of one pair of factors seperate independently of members of another pair of factors so all possible combinations of factors can occur in gametes

(random)

location of particular gene on a chromosome

-same for both homologous chromosomes

-ex. gene for flower color in peas

(diploid) contain both members of any pair of homologous chromosomes, so they possess 2 copies of any particular gene

(haploid) -sperm or egg; contain only one member of a pair of homologous chromosomes so they possess only one copy of part. gene

alternate or contrasting forms of a gene

ex. gene for flower color in peas has allele that produces purple and contrasting allele that produces white

combo of 2 alleles for a trait

during meiosis-homologous chromosomes seperate and alleles for any gene are seperated and distribued to different gametes

if same allele is received from each parent

"pure-breeding"

if contrasting alleles are received from parents

"hybrid"

only one allele is usually expressed at any time and physical expression of genotype

Dominant Allele=2 contrasting forms of gene are present at same time

Recessive Allele=not expressed when 2 contrasting forms of gene are present at same time

egg or sperm

ALWAYS haploid

ex. sperm- Y

      egg - y

Uses a homozygous recessive individual to determine genotype of individual that displays dominant phenotype and works backwards from offspring

follows 2 pairs of contrasting traits simultaneously from pure-breeding parents (P) through hybrid offspring (F1) to 3rd generation (F2)

-cannot seperate traits