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Mendelian Genetics. 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. Dominant Traits.
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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.
Dominant Traits • 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
Recessive Traits • 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
The Father of Modern Genetics • Gregor Mendel • Austrian Monk • Experimented with pea plants and noticed that they contained “factors” that were passed to offspring.
Tongue Rolling • Dominant
Tongue Folding • Recessive- you must have two genes to have this trait
Detached Earlobes • Detached Earlobes are dominant- only one gene of the pair necessary • Attached- recessive
Thumbs Hitchhikers' Thumb- Dominant Straight Thumb- Recessive
Relative Finger Length Index Longer than Ring- Dominant Ring Longer than Index- Recessive
Widow’s Peak Peak- Dominant Straight- Recessive
Whorl Counter-Clockwise- Recessive Clockwise-Dominant
As you begin working genetic problems, remember- genes come in pairs
Simple Dominant/Recessive Genetics Problems Homework Solutions
1. Black fur (B) in guinea pigs is dominant over white fur (b). Find the probability of a white offspring in a cross between two hybrid guinea pigs. 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 b _______% hybrid
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 B _____% purebred
4. bb x bb b b b b _________% black
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 b __________% white
Incomplete Dominance and Co-Dominance • Two traits combine or blend together to produce a different trait. • There is no dominant or recessive trait. Instead, both traits have about the sameinfluenceon the organism. • Use different letter for each trait: bb= black ww= white bw=gray
Examples: Andalusian Chickens BB x WW = BW
Roan Colored Horses and Cattle RR or BB x WW= RW or BW
Flower Colors RR x WW = RW