TEST CROSSES

TESTCROSS used to tell what genes an organism has Example: The genes of a TALL PARENT are UNKNOWN - COULD HAVE _____ BOTH LOOK ALIKE ! http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html

TESTCROSS used to tell what genes an organism has Cross an UNKNOWN parent with a ____________________________ and see results Offspring give a clue about the unknown parent’s genes

TESTCROSS t 50% will be TALL All offspring will 50% will be SHORT T T T t t t 50% will be TALL 50% will be SHORT All offspring will be TALL

DEAF DOGS Deafness in dogs is caused by a recessive allele. Deaf dogs have the genotype dd. A HEARING dog could have 2 possible GENOTYPES ______ ______ How do we tell which one it is?

TESTCROSS HEARING PARENT WITH DEAF PARENT D D D d d d If you get some deaf puppies, you know parent genotype was Dd NOT DD.

DRAGONS Firebreathing (F) in dragon is a dominant trait http://www.webweaver.nu/clipart/dragons3.shtml Firebreathing (F) in dragon is a dominant trait NON-firebreathing (f) is recessive. A firebreathing dragon could have 2 possible GENOTYPES ______ ______ How do we tell which one it is?

TESTCROSS FIREBREATHING PARENT WITH NON-FIREBREATHER F F F f f f If you get some NON-fire breathing dragons you know parent genotype was Ff NOT FF.