Why are recessive genes more common then dominant genes?

Question

I am taking genetics, and I cant figure it out. I think the answer is because if a gene is dominant that you can die and wont carry the gene so all that is left are the recessive genes. I dont really know the answer, I just want to find out!!!

Answer 1

It isn't that recessive genes or dominant genes are more common. What usually happens is the the mutant is less common.

There are multiple types of effects that result from mutations. The most common effect is a loss of function. Loss of function mutations result in recessive phenotypes (because one good copy of the gene still gives you the phenotype), thus they are recessive alleles. In these cases, usually the recessive gene is the minority.

Some mutations result in gain of function, that is they cause a new protein that causes a new phenotype. Now all you need is a single copy of this mutated gene to get the phenotype, hence it is dominant. In these cases, the dominant allele is the minority.

Over time selection and other factors change the gene frequencies, so that in the end there is no hard and fast rule about the frequency of dominant vs. recessive alleles.

Answer 2

It all depends on how common that gene is in the population's gene pool. Don't assume that all alleles (forms of a gene) are equally common.

Think about a big bowl of checkers. If the bowl has an even number of black checkers and red checkers, then I would expect to pull out a black and a red about half of the time.

OK, now let's say that the black checker represents a dominant allele. If I pull out a black and a red, then the individual would have the dominant phenotype.

What if the bowl has 2 black checkers and 200 red checkers. Even if the black checkers are dominant, I wouldn't expect to get a black checker when I randomly draw two checkers from the bowl. They just aren't that common in the bowl. They're rare.

In the case of human blood type, Type O is most common, even though O is recessive to both A and B. Why so many Type Os? Imagine a big bowl of magnetic letters like you stick on the refrigerator. Lots and lots of the letters are Os. Way fewer of the letters are As and Bs. Now close your eyes and draw out two letters. What are the chances that you took OO? Pretty likely because most of the letters are Os. What are the chances that you took AO or BO? Still pretty good. But what are the chances that you drew AB, AA, or BB. Less likely because most of the letters are Os.

So widow's peak is dominant, but not many people have it. In my bio classes, I usually have about 4 to 6 people with widow's peak in a class of 30 students.

Answer 3

Generally, they aren't more common, but there are certain situations where a recessive gene is more common. It depends on what that gene is for. For example, blue eyes is recessive but it is common in the population especially in regions dominated by Caucasians. One reason is gene for blue eyes is not fatal to have and in some cases it even increases the chances for mating. Some people including me find it more attractive, aight Ross?

Answer 4

Recessive genes AREN'T necessarily more common than dominant gene. For example, brown hair and brown eyes are dominant and more common.

But, if you use the 6 fingered hand as an example (5 fingers is recessive), the answer belongs to evolution.

Answer 5

dont know what your thinking, but dominant genes are more common

Answer 6

I agree with "the lil one" i seem to be hearing birds and bees...