genotype

Examples of genotype in the following topics:

• Phenotypes and Genotypes

  • The observable traits expressed by an organism are referred to as its phenotype and its underlying genetic makeup is called its genotype.
  • An organism's underlying genetic makeup, consisting of both physically visible and non-expressed alleles, is called its genotype.
  • Johann Gregor Mendel's (1822–1884) hybridization experiments demonstrate the difference between phenotype and genotype.
  • Therefore, the F1 plants must have been genotypically different from the parent with violet flowers.

• Hardy-Weinberg Principle of Equilibrium

  • The Hardy-Weinberg principle can be used to estimate the frequency of alleles and genotypes in a population.
  • If two alleles are drawn at random from the gene pool, we can determine the probability of each genotype.
  • Therefore, by knowing the recessive phenotype and, thereby, the frequency of that genotype (16 out of 100 individuals or 0.16), we can calculate the number of other genotypes.
  • The horizontal axis shows the two allele frequencies p and q and the vertical axis shows the expected genotype frequencies.Each line shows one of the three possible genotypes.
  • Use the Hardy Weinberg equation to calculate allelic and genotypic frequencies in a population

• Mendel's Law of Independent Assortment

  • Independent assortment allows the calculation of genotypic and phenotypic ratios based on the probability of individual gene combinations.
  • Arranging these gametes along the top and left of a 4 × 4 Punnett square gives us 16 equally likely genotypic combinations.
  • From these genotypes, we infer a phenotypic ratio of 9 round/yellow:3 round/green:3 wrinkled/yellow:1 wrinkled/green .
  • It would be extremely cumbersome to manually enter each genotype.
  • Rather than writing out every possible genotype, we can use the probability method.

• The Punnett Square Approach for a Monohybrid Cross

  • Each box then represents the diploid genotype of a zygote, or fertilized egg, that could result from this mating.
  • Because each possibility is equally likely, genotypic ratios can be determined from a Punnett square.
  • In this case, only one genotype is possible.
  • Notice that there are two ways to obtain the Yy genotype: a Y from the egg and a y from the sperm, or a y from the egg and a Y from the sperm.
  • Punnett square analysis can be used to predict the genotypes of the F2 generation.

• Alternatives to Dominance and Recessiveness

  • In this case, the genotypic ratio would be 1 CRCR:2 CRCW:1 CWCW, and the phenotypic ratio would be 1:2:1 for red:pink:white.
  • In a self-cross between heterozygotes expressing a codominant trait, the three possible offspring genotypes are phenotypically distinct.
  • However, the 1:2:1 genotypic ratio characteristic of a Mendelian monohybrid cross still applies.
  • Note that when many alleles exist for the same gene, the convention is to denote the most common phenotype or genotype among wild animals as the wild type (often abbreviated "+"); this is considered the standard or norm.
  • All other phenotypes or genotypes are considered variants of this standard, meaning that they deviate from the wild type.

• Epistasis

  • The recessive yellow genotype is epistatic to the B gene: mating two heterozygotes (BbEe) results in a 9:3:4 ratio of black (B_E_) to brown (bbE_) to yellow (__ee) offspring.
  • Therefore, the genotypes AAcc, Aacc, and aacc all produce the same albino phenotype.
  • Homozygous recessive expression of the W gene (ww) coupled with homozygous dominant or heterozygous expression of the Y gene (YY or Yy) generates yellow fruit, while the wwyy genotype produces green fruit.
  • That is, every possible genotype other than aabb results in triangular seeds; a cross between heterozygotes for both genes (AaBb x AaBb) would yield offspring with a phenotypic ratio of 15 triangular:1 ovoid.
  • The recessive c allele does not produce pigmentnand a mouse with the homozygous recessive cc genotype is albino regardless of the allele present at the A locus.

• Genetic Analysis

  • It is a commonly used and extremely powerful tool for genotyping and epidemiology studies for pathogenic microorganisms.
  • These techniques allow the identification of the genotype (i.e.
  • Genotypic variations exist in microbes and these include mutations, gene transfer by transformation, conjugation, and transduction.

• Genetic Engineering

  • In genetic engineering, an organism's genotype is altered using recombinant DNA, created by molecular cloning, to modify an organism's DNA.
  • Genetic engineering is the alteration of an organism's genotype using recombinant DNA technology to modify an organism's DNA to achieve desirable traits.

• DNA Analysis Using Genetic Probes and PCR

  • Genotyping of pathogenic isolates provides valuable support during investigations of suspected outbreaks and when tracing infectious diseases.
  • It is well established that genotyping of pathogenic isolates provides valuable support for the investigation of suspected outbreaks, the detection of unsuspected transmission, the tracing of infectious agents within a community, and the identification of possible sources of infection for newly diagnosed cases.

• Coupling Specific Genes to Specific Organisms Using PCR

  • Common PCR protocols in labs today include knockout genotyping, fluorescence genotyping and mutant genotyping.