Gene for-gene hypothesis & its validty in the present scenario
AipotuI | Hypothesis | Gene
Thrifty gene hypothesis - an overview | ScienceDirect …
The thrifty phenotype hypothesis arose from challenges posed to the thrifty gene hypothesis. The thrifty phenotype hypothesis theorizes that instead of the "thrifty factors" arising from genetic factors, that instead it is a direct result of the environment within the womb during development. The development of insulin resistance is theorized to be directly related to the body "predicting" a life of starvation for the developing fetus.
A suggested different approach to the problem is the suggestion that rather than selection favouring a few genes that are "thrifty", we possess a genome that is by default "thrifty" selected primarily due to epigenetic events. This is a combination of the thrifty phenotype and thrifty genotype hypotheses called the "thrifty epigenomic hypothesis". The basic idea is that there has never been an opportunity in history to develop "unthrifty" genes because of the extreme pressure to select for those genes that promote fitness and survival through energy budgets. This idea therefore suffers from essentially the same problems as the original thrifty gene hypothesis because the evidence that such extreme pressure exists is very weak.
One gene–one enzyme hypothesis | biology | …
Knafo, as earlier described, tested 3-year-olds and, confirming the orchid hypothesis, found that kids with the more plastic DRD4-7R variant and warm, engaged parenting were more prosocial than even warmly parented kids with the gene’s more common 4R form. These 7R kids with good parents not only shared their Bambas; they were more likely to pick up pencils a researcher had “accidentally” knocked onto the floor, express sympathy when a researcher bumped her knee on the table, or help find and then comfort a missing doll.
This is just one study. But the additive effect seems to argue well for the orchid hypothesis. And the absence of significant effect in boys with just one plasticity variant may suggest why studies on individual candidate genes produce such varying results: The effect of any one plasticity gene may depend heavily on whether a person also carries a second.
SELFISH GENE HYPOTHESIS - Psychology Dictionary
To remedy this, Caspi and Moffitt, in their 2010 paper, call for whole-genome studies that include environmental measures. If done well, such studies might go a long way toward proving or disproving the hypothesis. Meanwhile, some orchid-hypothesis researchers are looking for physiological effects of orchid variants, including heightened gene expression and other epigenetic changes.
There is also, finally, an evolutionary argument for the importance of these polymorphisms: These variants, Belsky and others note, appear to have emerged and then rapidly expanded through humankind over the last 50,000 to 100,000 years. Of the leading orchid-gene variants — the short SERT, the 7R DRD4, the more plastic version of the MAOA gene — none existed in humans 80,000 years ago. But since emerging through mutation (or, possibly, through interbreeding with other hominids), they have spread into 20 to 35% of the population.
Knudson hypothesis: Tumor Suppressor Gene | Blog de …
Gene-For-Gene Hypothesis Flash Animation
What can you conclude about the "two-gene hypothesis"?
Thrifty gene hypothesis - OurMed
The One Gene-One Enzyme Hypothesis - …
If the orchid-gene hypothesis is to hold up, ..
Thesis and Essay: Gene For Gene Hypothesis Ppt ateam …
Thrifty Gene Hypothesis Obesity - UW Milk Quality
The hallmark pathology of Parkinson’s disease is the damage and death of dopamine producing neurons in the brain. Dopamine plays a role in controlling movement, cognition, learning, and mood, explaining the dementia and difficulty with motor control exhibited by patients with deficits in the production of this key neurotransmitter. The a-synuclein gene was one of the first to be implicated in this disease. It produces a protein that can, in certain circumstances, aggregate to form bundles that are a major component of Lewy bodies—fibers that disrupt normal cell processes. Recently researchers have discovered other mechanisms by which this protein damages or kills dopamine-producing neurons, as well as other genes that may also play a role in driving the disease.
What is the one gene-one polypeptide hypothesis? | …
Yet such plasticity genes serve a group well if they remain in a minority, since they create a populace of steady do-ers (dandelions) mixed with individuals of more volatile temperament but greater range of behavior (orchids). Thus some evolutionary anthropologists have argued that some of the traits associated with these variants, such as the high sensation-seeking and risk-taking found in 7R carriers in many DRD4 studies, may have helped drive human expansion around the globe; and in fact the 7R variant is found in its highest rates in populations5 that migrated fastest and furthest from Africa and Arabia. The sensitivity to cues and flexibility of response that orchid genes provide, at both the individual and group levels, may well have been essential to our human success.
What is the Evidence for the Good Genes Hypothesis? | …
It may seem odd to link such communal achievements to bits of behavior such as a toddler’s willingness to share Bambas. Yet if the orchid hypothesis is right, the genes and genetic dynamics that help create some of our most grievous frailties and foibles — anxiety and aggression, melancholy and murder — may also underlie our greatest strengths and successes. Something to ponder next time you’re offered a sweet.
the Evidence for the Good Genes Hypothesis?
Yet the orchid hypothesis faces new obstacles as the vulnerabilty-gene paradigm out of which it grew comes under closer scrutiny. With genetics moving toward sophisticated whole-genome studies using data from thousands of people, researchers can no longer rely solely on the kind of small-scale, individual-gene studies that led to the orchid hypothesis. (Such studies are called candidate-gene studies, since they study a gene already suspected of having an effect.) If the orchid-gene hypothesis is to hold up, researchers must broaden and deepen their evidence. Will it prove just a pretty story — or will the orchid hypothesis show the flexibility and strength to adapt among changing conditions of proof?
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