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.
What is Personal Genetics? What is genotype? What is phenotype? Home What is genotype? Rare heterozygous loci due to recurrent mutation; natural selection purges populations of their "load" of mutations. Balance school held that many loci will be heterozygous in natural populations and heterozygotes maintained by "balancing selection" heterozygote advantage.
Selection thus plays a role in maintaining variation. How do we measure variation? To show that there is a genetic basis to a continuously varying character one can study 1 resemblance among relatives : look at the offspring of individuals from parents in different parts of the distribution; can estimate heritability more later.
Took off in mid 60's Lewontin and Hubby, ; Harris, ; still used. Grind up organism in buffer, apply homogenate to gel starch, acrylamide , apply electric field, proteins migrate in gel according to charge, stain gel with histochemical stain for enzyme activity, bands reveal variation.
The technique provides a minimum estimate because different amino acid sequences may migrate at the same rate in the gel. DNA variation.
Measure the genetic material directly; sequencing is the most precise but the most laborious; restriction enzyme analysis faster but has less information. These techniques have revealed that there is even more genetic variation that what was revealed by protein electrophoresis. Hence the debate between the Classical and Balance schools of genetic variation has evolved into a debate about the forces maintaining genetic variation: the Neutralist-Selectionist controversy or debate.
Some loci are neutral; others under selection more in lecture on Molecular Evolution. The debate is not over. This refers to the range of phenotypes occurring in patients with the same genetic condition. A patient with a particular variant may have mild symptoms, while another patient with the same variant has severe disease. As with reduced penetrance, the reasons for variable expressivity are not well understood. If a genetic condition has highly variable symptoms, it may be more challenging to diagnose.
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