What is the difference between genotype and phenotype in a punnett square

The Punnet square shows the possible genotypes of the offspring. Three quarters of the possible combinations of alleles one RR and two Rr will give rise to plants that produce seeds with the dominant round phenotype.

Only one combination of the male and females alleles rr will give rise to plants that produce seeds with the recessive, wrinkled phenotype.

This means the expected ratio of offspring plants that produce round seeds to plants that produce wrinkled seeds will be The phenotype is influenced by the genotype and factors including:. Phenotype examples Environmental factors that may influence the phenotype include nutrition, temperature, humidity and stress. Flamingos are a classic example of how the environment influences the phenotype.

Whilst renowned for being vibrantly pink, their natural color is white — the pink color is caused by pigments in the organisms in their diet. A second example is an individual's skin color. Our genes control the amount and type of melanin that we produce, however, exposure to UV light in sunny climates causes the darkening of existing melanin and encourages increased melanogenesis and thus darker skin. Observing the genotype, however, is a little more complex. Genotyping is the process by which differences in the genotype of an individual are analyzed using biological assays.

Previously, genotyping would enable only partial sequences to be obtained. Now, thanks to major technological advances in recent years, state-of-the-art whole genome sequencing. Understanding the relationship between a genotype and phenotype can be extremely useful in a variety of research areas.

A particularly interesting area is pharmacogenomics. Genetic variations can occur in liver enzymes required for drug metabolism, such as CYP For pharmaceutical companies and physicians, this knowledge is key for determining recommended drug dosages across populations.

Making use of genotyping and phenotyping techniques in tandem appear to be better than using genotype tests alone. In a comparative clinical pharmacogenomics study , a multiplexing approach identified greater differences in drug metabolism capacity than was predicted by genotyping alone.

The family tree in Figure 1 shows how an allele can disappear or "hide" in one generation and then reemerge in a later generation. In this family tree, the father in the first generation shows a particular trait as indicated by the black square , but none of the children in the second generation show that trait.

Nonetheless, the trait reappears in the third generation black square, lower right. How is this possible? This question is best answered by considering the basic principles of inheritance. Mendel's principles of inheritance. How do hidden genes pass from one generation to the next? Although an individual gene may code for a specific physical trait, that gene can exist in different forms, or alleles. One allele for every gene in an organism is inherited from each of that organism's parents.

In some cases, both parents provide the same allele of a given gene, and the offspring is referred to as homozygous "homo" meaning "same" for that allele.

In other cases, each parent provides a different allele of a given gene, and the offspring is referred to as heterozygous "hetero" meaning "different" for that allele. Alleles produce phenotypes or physical versions of a trait that are either dominant or recessive.

The dominance or recessivity associated with a particular allele is the result of masking, by which a dominant phenotype hides a recessive phenotype.

By this logic, in heterozygous offspring only the dominant phenotype will be apparent. The relationship of alleles to phenotype: an example. Dominance, breeding experiments, and Punnett squares. Figure 4: A brown fly and a black fly are mated. Figure 5: A Punnett square. Figure 6: Each parent contributes one allele to each of its offspring.

Thus, in this cross, all offspring will have the Bb genotype. Figure 7: Genotype is translated into phenotype. In this cross, all offspring will have the brown body color phenotype. The phenomenon of dominant phenotypes arising from the allele interactions exhibited in this cross is known as the principle of uniformity, which states that all of the offspring from a cross where the parents differ by only one trait will appear identical.

How can a breeding experiment be used to discover a genotype? Breeding the flies shown in this Punnett square will determine the distribution of phenotypes among their offspring.

If the female parent has the genotype BB, all of the offspring will have brown bodies Figure 9, Outcome 1. In this way, the genotype of the unknown parent can be inferred. Figure 9. Figure The phenotypic ratio is brown body: black body. This observation forms the second principle of inheritance, the principle of segregation, which states that the two alleles for each gene are physically segregated when they are packaged into gametes, and each parent randomly contributes one allele for each gene to its offspring.

Can two different genes be examined at the same time? Figure The possible genotypes for each of the four phenotypes. The dihybrid cross: charting two different traits in a single breeding experiment. Figure These are all of the possible genotypes and phenotypes that can result from a dihybrid cross between two BbEe parents. On the upper left, the female parent genotype is uppercase B lowercase b, uppercase E lowercase e. Uppercase B, uppercase E is labeled to the left of the top quadrant; lowercase b, lowercase e is labeled outside the second left quadrant; uppercase B, lowercase e is labeled outside the third left quadrant; and lowercase b, uppercase E is labeled outside the fourth left quadrant.

On the upper right, the male parent genotype is also uppercase B lowercase b, uppercase E lowercase e. Uppercase B, uppercase E is labeled to the right of the top quadrant; lowercase b, lowercase e is labeled to the outside the second right quadrant; uppercase B, lowercase e is labeled outside the third right quadrant, and lowercase b, uppercase E is labeled outside the fourth right quadrant. The offsprings' genotype and phenotype is represented in each of the cells of the Punnett square.

Nine of the 16 cells contain brown-bodied flies with red eyes. Of these nine flies, one has the genotype uppercase B, uppercase B, uppercase E uppercase E; four have the genotype uppercase B lowercase b, uppercase E lowercase e; two have the genotype uppercase B uppercase B, uppercase E lowercase e; and two have the genotype uppercase B lowercase b, uppercase E uppercase E. Three cells contain brown-bodied flies with brown eyes. Of these three flies, one has the genotype uppercase B uppercase B, lowercase e lowercase e and two have the genotype uppercase B lowercase b, lowercase e lowercase e.

Three cells contain black-bodied flies with red eyes. Of these three flies, one has the genotype lowercase b lowercase b, uppercase E uppercase E and two have the genotype lowercase b lowercase b, uppercase E lowercase e. The final cell contains a black-bodied fly with brown eyes; this fly has the genotype lowercase b lowercase b, lowercase e, lowercase e.

The impact of Mendel's principles. Seminal experiments on inheritance. Key Questions What is non-nuclear inheritance? How can the same genotype give you a different disease? Who was Gregor Mendel? Key Concepts testcross dihybrid cross Principle of Independent Assortment. Topic rooms within Genetics Close.