Download Test Cross

Test Cross
Test Cross
• When an organism has the dominant
phenotype, then its genotype can be either
heterozygous or homozygous dominant (you
can’t tell by looking at it). In order to find out
we must do a test cross using a homozygous,
recessive organism.
Test Cross
• A test cross is the crossing of an organism,
with an unknown genotype, to a homozygous
recessive organism (tester).
• A Test cross can be used to decide the
genotype of the F1 generation. The test cross
can be used to support the idea that the
recurrence of the recessive character in the F2
generation is due to the heterozygous
condition of the F1.
Test Cross
Linked Genes
• Linked genes are genes that tend to be
inherited together because they are close
together on the same chromosome.
• These genes tend not to separate during
crossing over.
• EX) Red hair and freckles
• EX) Wings and body color in fruit flies