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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. - PowerPoint PPT Presentation
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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' Thumb- Dominant
Straight Thumb- Recessive
Index Longer than Ring- Dominant
Ring Longer than Index- Recessive
Peak- Dominant Straight- Recessive
Counter-Clockwise- Recessive 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
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 purebredblack and a hybrid black guinea pig.
_____% same phenotypes as parents
6. Bb x bb
B b
b
b
__________% white
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