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The Lyon hypothesis states that in cells with multiple X chromosomes, all but one is inactivated during mammalian embryogenesis. X-inactivation leads to clumped chromatin termed Barr bodies, which are generally considered inert. This formation of Barr bodies is called Lyonization. In humans the X chromosome that is inactivated is determined by chance. In marsupials, however, the paternal X chromosome is always inactivated. Inactivation is achieved by methylation of the X chromosome DNA, a common way in which the cell silences particular genes. Certain animals have their coloring patters dictated by this phenomenon. For example, female Calico cats have unique patterns of fur due to certain areas where different X chromosomes are inactived. The X chromosomes that are activated express different coloring genes and lead to their mosaic fur color. However, there are now reports that women still express many genes from their inactive X chromosomes, and that different women express different genes from the inactive X. Research by Carrel and Willard (2005) indicates that 15% of the genes on the inactive X chromosome are actually active across all women, and a further 10% of genes were switched on in some women. The hypothesis was first stated by Mary F. lyon in 1961 while she was studying the genetic consequences of radiation exposure, and therefore bears her name.

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An organism that can only be seen with a microscope?

An example of an organism that can only be seen with a microscope is a single-celled organism like bacteria or protists. These organisms are too small to be visible to the naked eye but can be observed under a microscope due to their size.


The range of factors under which an organism functions and survives is known as?

The range of factors under which an organism functions and survives is known as its ecological niche. This includes the physical environment the organism lives in, as well as its interactions with other species and resources in its ecosystem.


The process in which a cell destroys itself for the good of the organism is called c--------?

The process in which a cell destroys itself for the good of the organism is called apoptosis. Apoptosis is a tightly regulated mechanism that removes damaged or unnecessary cells, helping to maintain tissue homeostasis and overall organismal health.


Why do we tan under the sun?

We tan under the sun because our skin produces more melanin, a pigment that darkens the skin, as a natural defense mechanism against harmful UV rays.


Why would cells from the same organism look different under a microscope?

Cells from the same organism may look different under a microscope due to variations in their development, function, and stage of the cell cycle. Different cell types within the same organism have distinct structures and functions, which can result in varied appearances when viewed under a microscope. Additionally, factors like cell maturity, health, and exposure to different environments can also contribute to differences in cell appearance.

Related Questions

How is oxytocin an example of a hormone that is under positive regulaton?

Yes it is an example. There a positive feed back mechanism take place


An organism that can only be seen with a microscope?

An example of an organism that can only be seen with a microscope is a single-celled organism like bacteria or protists. These organisms are too small to be visible to the naked eye but can be observed under a microscope due to their size.


The burrow a chipmunk digs under a patio stone is an example of an?

it could be the habitat (the place in which an organism lives)... that is a guess so don't get mad at me if it isn't ;)


How does an organism's niche differ from its habitat?

Niche: an organism's role in the environment. Habitat: specifically where it lives. For example, many organisms maybe have the same habitat (under a log, if we're considering insects), but as long as they occupy different niches, they will not be in competition.


Where unicellular organism is seen?

Under microscopes


What organism is found under a stone?

bacteria :)


How do you change a fuel pump on a 2001 Mazda Protege?

release gas pressure, get to the pump mechanism under the back seat, replace the pump in the mechanism


What is organisim?

An organism is a living thing. It can be a micro-organism, which can only be seen under a microscope, a fungus, a plant or an animal.


Your outside door handle mechanism has snapped is this under warranty?

Check with the dealership.


The range of factors under which an organism functions and survives is known as?

The range of factors under which an organism functions and survives is known as its ecological niche. This includes the physical environment the organism lives in, as well as its interactions with other species and resources in its ecosystem.


The process in which a cell destroys itself for the good of the organism is called c--------?

The process in which a cell destroys itself for the good of the organism is called apoptosis. Apoptosis is a tightly regulated mechanism that removes damaged or unnecessary cells, helping to maintain tissue homeostasis and overall organismal health.


An individual organism?

Species (under the Biological Species Concept).