Can a dominant gene become recessive?

Question

...or a recessive gene become dominant? If so, what causes these shifts?

Answer 1

What you are asking about may be polymorphism. In one situation the expressed trait 'A' will do well combined with 'a' but not 'b'. While trait 'B' does well with 'b' but not 'a'
For example, one type of male might do better with one type of female, another type of male might do better with another type of female, and the frequencies of the two types of female might be such that the two types of male do equally well on the average. This implies that patterns of dominance can determine whether polymorphism is maintained.
polymorphism (pol-ee-mor-fiz-um) [Gk. polus, many + morphe, form] The coexistence of two or more distinct forms (polymorphic characters) in the same population. Variant forms of a particular gene that occur simultaneously in a population.
Balanced polymorphism is maintained by natural selection. Two distinct forms of the same gene that are selected by certain situations from one population. The human blood groups are examples of polymorphism.
This is not dominance in the Mendalian sense. It is rather dominance in the sense of advantage. Genes have numerous effects so genes are of importance to the organism by possessing an overall advantage or disadvantage very seldom are they neutral.

Answer 2

Since dominant genes "mask" recessive genes, you would not know someone had a recessive gene until they had offspring. Then, if you inherited one recessive from each parent...you now show the genotype & phenotype of the recessive; as its is the only gene available. Some really good examples for this are in medicine: hemophilia, sickle cell disease, Tay-Sacs, etc. But even blood-typing (Type O is the recessive; A and / or B are the dominant--so a person who is type O has two "absent" genes).

Answer 3

A gene (let's say gene A) can be dominant vs another gene (gene B), but recessive vs a third one (gene C).

Example, green eyes are dominant vs blue eyes, but recessive vs brown eyes.

Answer 4

We don't speak of dominant and recessive genes -- we speak of dominant and recessive alleles. A dominant allele could become recessive through a mutation that rendered its gene product useless.

Answer 5

no! just kidding i dont know