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Your genes, located on your chromosomes contain dominant and recessive traits which were inherited from your parents and grandparents. Some of your characteristics are caused by only one gene from each chromosome. Traits that show themselves over recessive or hidden traits Remember that genes come in pairs- if only one is dominant the organisms will show that trait Examples: Tongue rolling, Detached earlobes Traits that are masked or hidden by a dominant trait Genes come in pairs- if only one is recessive it will not be expressed in the individual Examples: Attached earlobes, straight thumb Gregor Mendel Austrian Monk Experimented with pea plants and noticed that they contained “factors” that were passed to offspring. Dominant Recessive- you must have two genes to have this trait Detached Earlobes are dominant- only one gene of the pair necessary Attached- recessive Hitchhikers' ThumbDominant Straight ThumbRecessive Index Longer than RingDominant Ring Longer than IndexRecessive Peak- Dominant Straight- Recessive Counter-ClockwiseRecessive Clockwise-Dominant Homework Solutions B b B b ____%white 2. Black fur (B) in guinea pigs is dominant over white fur (b). Find the probability of a hybrid offspring in the cross: BB x Bb B B B _______% hybrid b 3. Black fur (B) in guinea pigs is dominant over white fur (b). Find the probability of a purebred offspring in a cross: BB x BB B B B _____% purebred B 4. bb x bb b b b _________% black b 5. Find the probability of an offspring with the same phenotype as its parents in a cross between a purebred black and a hybrid black guinea pig. _____% same phenotypes as parents 6. Bb x bb B b b __________% white b Two traits combine or blend together to produce a different trait. There is no dominant or recessive trait. Instead, both traits have about the same influence on the organism. Use different letter for each trait: bb= black ww= white bw=gray BB x WW = BW RR or BB x WW= RW or BW RR x WW = RW