Some observable traits in humans are dimples, earlobes, tongue-rolling, cleft chin, hairline, and freckles. The relationship between the frequency of a trait in a population and whether the trait is dominant or recessive because in inherited human traits, the offspring can either have dimples or no dimples.
formula: p2 + 2pq + q2 = 1 p+q=1 p = dominant (A) allele frequency q = recessive (a) allele frequency q2 = homozygous recessive frequency p2 = homozygous dominant frequency 2pq = heterozygous frequency
Because it has things
It depends on the family but I assume that its a recessive gene.
This is a principle of population genetics based on the Hardy-Weinberg Principle. A trait that is neither selected for nor against will remain in the population at the same frequency. In most populations the frequency values can be back calculated from the percentage of the population that is homozygous recessive. The basic equations are p+q=1 and p (squared) + 2pq + q (squared)=1 The value of q (squared) is the frequency of homozygous recessive individuals in the population. So if 20% of the population is homozygous recessive, then q (squared) is .20. This makes q=.45 (approx.) So, in order to produce a population where 20% of all individuals are homozygous recessive a full 45% of all the alleles at that gene locus are recessive. p=.55 p+q=.55+.45=1.0 Now all the numbers for the homozygous dominant and heterozygotes can be calculated. The approximate percent of the population that is homozygous dominant is 30% with 50% of the population represented by heterozygotes. .3+.5+.2=1 As the gene frequency for an allele decreases the less likely two individuals that are heterozygous for the trait will be to breed and produce either a homozygous recessive individual or a homozygous dominant. In the case where a characteristic is dominant and has a low frequency, the trait will be seen in family lines but rarely has the opportunity to be passed beyond a small population because there is no selection for the characteristic. An example of this is 6 fingered (polydactyl) individuals, which is a dominant trait. They exist in the population but they are rarely seen.
p2 + 2pq + q2 = 1 and p + q = 1p = frequency of the dominant allele in the populationq = frequency of the recessive allele in the populationp2 = percentage of homozygous dominant individualsq2 = percentage of homozygous recessive individuals2pq = percentage of heterozygous individuals
Homozygous recessive genotype
Alleles can be dominant or recessive
Let us say you have three alleles in a population of beetles. Two colors; brown is recessive to green. Thus you have; GG, which is homozygous dominant and green, you have Gb, which is heterozygous and also green. Then you have bb, which is homozygous recessive. This is your population of beetles. What do you think the allele frequency would be if GG, the homozygous dominant, either immigrated, or emigrated out of or into your population of beetles? Since the frequency of Gb and bb would necessarily go down statistically you would see more green morphologies and a change in genetic allele frequency. Assuming normal conditions.
Simple example. You know hair color is under genetic control. Two types, blond ( which is recessive ) and brown ( which is dominant ) exist in our population. These two alleles are in a 75% to a 25% frequency. ( dominant to recessive ) if that frequency changed to 60% to 40% you could say that evolution had taken place. Evolution is the change in allele frequency in a population of organisms over time. ( example very simplified ) PS Scientist do not prove things. They support their work with the evidence.
IT always varies on the X cromosomes
There is dominant and there is recessive. There is no dominant recessive. A dominant gene will always be expressed when present, such as in the homozygous dominant genotype (RR), or heterozygous genotype (Rr). A recessive allele is only expressed when the genotype is homozygous recessive (rr).
Harmful recessive or dominant traits will remain in the population as long as the individuals are unaffected or only moderately affected allowing them to reproduce, or if recessive, they are at a low enough frequency in the population that they are rarely expressed and therefore not selected against at a significant rate.