Two (together).
recessive is when you have another allele that supress the recessive one, you have to thing how this could be done in a methabolic pathway, and you will see that exist many ways for an allele be dominant and the other recessive (you just can say dominant and recessive if you are talking at alleles ,this is genes at the same locus. my mother language is no inglish maybe i have comit many gramatical errors but what i am saying is correc i am student of biotechnology.
Continuous variation is a variation that is distributable; under a normal curve. Height is an example of this with all heights being along a continuum of heights within populations, at least. This distribution of traits is usually controlled by many alleles in a additive fashion. Polygenic. Discontinuous variation is of one trait, allele, or the other. Blood groups are an example of this. A, B , O. You can only have two alleles here, so AA and AB and OO and AO, AB etc. are the expressed ( less the recessive O, except homozygous ) traits. These are single variations based on one allele and are not distributable along a continuum.
Wikipedia says:The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype. The Punnett square is a tabular summary of possible combinations of maternal alleles with paternal alleles.[1] These tables can be used to examine the genotypic outcome probabilities of the offspring of a single trait (allele), or when crossing multiple traits from the parents. The Punnett Square is a visual representation of Mendelian inheritance. It is important to understand the terms "heterozygous", "homozygous", "double heterozygote" (or homozygote), "dominant allele" and "recessive allele" when using the Punnett square method. For multiple traits, using the "forked-line method" is typically much easier than the Punnett square. Phenotypes may be predicted with at least better-than-chance accuracy using a Punnett square, but the phenotype that may appear in the presence of a given genotype can in some instances be influenced by many other factors, as when polygenic inheritance and/or epigenetics are at work.
as many as needed
four segments are needed
Only one dominant allele is needed to display the dominant phenotype. Dominant alleles are expressed when present, masking the effect of recessive alleles.
The reason many harmful alleles are recessive is because the harmful alleles that were dominant stopped the carrier from reproducing so the allele was not carried on. A dominant trait is expressed if present and would harm the carrier. A recessive trait however can remain in the genotype of an individual and not the phenotype so they will not be harmed by the trait but can pass it on to offspring. In short: dominant harmful alleles stopped the carriers from producing so the allele was not spread.
Actually a chromosome consists of many genes/alleles and is neither recessive or dominant in and of itself.
8
In codominance, there are at least two alleles contributing to the phenotype of an individual, each allele independently expressed. This means that both alleles are fully expressed in the heterozygous genotype, resulting in a distinct phenotype.
Each gene has a dominate and recessive allele, so there are two types of alleles in each gene. The dominate allele is stronger than the recessive allele unless there are two recessive alleles.
2
The smooth pod phenotype in pea plants is typically associated with a specific gene controlled by a single locus with two alleles: one for smooth pods (dominant) and one for wrinkled pods (recessive). The possible genotypes for the smooth pod phenotype are homozygous dominant (SS) and heterozygous (Ss). Therefore, there are two genotypes that can express the smooth pod phenotype.
A gene with one completely dominant allele and two recessive alleles can produce two different traits. The dominant allele will express its trait regardless of whether it is paired with another dominant or a recessive allele, while the two recessive alleles will express their trait only when paired together. Therefore, the possible combinations of alleles result in one dominant trait and one recessive trait.
Gene mutation causes the phenotype frequency in a population to change after each generation.
NO, because a dominant phenotype could either be homozygous or a heterozygous.so unless you are sure about the genotype of parents we can't determine it...but we can determine the genotype of a person showing reccessive phenotype, as a recessive trait always expresses itself in a homozygous condition...
If the allele is dominant, you only need one copy for it to be expressed in the phenotype (you have TWO alleles for each trait) If the allele is dominant, you only need one copy for it to be expressed in the phenotype (you have TWO alleles for each trait)