Transcript LEQ: How do genes assort independently?

LEQ: How do genes
assort independently?
9.4 to 9.6
Homologous
Chromosomes
 Each chromosome of a
homologous pair carries a
copy for the same gene.
 For most genes there are
two alleles. What would be
the exception?
 Traits on sex
chromosomes.
 The alleles can be the same
 Homozygous
 The alleles can be different
 Heterozygous
Dihybrid Cross
 Genetic Cross of individuals
differing in 2 traits
 16 boxes
 Determine possible gametes
 A with P, A with p, a with P
and a with P
 Keep alleles together (A with
A and P with P)
 Capitol letter before
lowercase
Independent Assortment
Independent Assortment
 When Mendel conducted
dihybrid crosses he noticed
new gene combinations
(different from the P and F1)
 From that he came up with the
Law of Independent
Assortment:
 Each pair of alleles segregates
independently from other
pairs of alleles during gamete
formation
 The genes did not have to be
inherited together
Independent Assortment
 When do genes
independently assort?
 Metaphase 1 of Meiosis
Test Cross
 A cross between an
individual of unknown
(homozygous dominant or
heterozygous) genotype
and a homozygous
recessive individual
 If any offspring are
recessive, then…
 Unknown is heterzygous
 If all offspring are
dominant, then…
 Unknown is homozygous