Which of the following ways do the cell membranes of Archaea differ from the cell membranes found in Bacteria?
A) The Archaea have cell membranes made of ether-linked hydrocarbons which branch, while Bacterial membranes are made of ester-linked fatty acids. Archaea membrane lipids are ether-linked while this is not true for bacteria and eukaryotes that have ester-linked membrane lipids. Plant cells use cellulose for structure while bacterial cells use peptidoglycan layer outside the membrane for structure and fungi use chitin. Archaea lack peptidoglycan in their cell walls.
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Which of the following is found in animal cell membranes? (Select all that apply.)?
The answers are : B) Cholesterol, D) Phospholipids and E) Protein This is because animal cell membranes are normally composed of proteins (comparable to icebergs) floating in an abundance of phospholipids and cholesterol (comparable to a sea). Hence, the whole membrane is a fluid structure (as according to Singer and Nicholson's Fluid mosaic model). Nucleic acids are only present in the interior of the nucleus in an animal cell and NEVER in the cell membrane.
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is this true?
thats what my grandmother always told me she used to use this crystall stone thing and get it wet then applied it.i just remember hiding it in the garbage when i was like five.it tasted awful.and yes i know from experiance.but any ways it was the more safe solution. and i found this on the internet so here. "According to Ms. Garland most commercial brands of antiperspirants and deodorants contain either aluminum chlorohydrate or aluminum zirconium. These compounds are very soluble and are readily absorbed by the body. Once in the body, the aluminum portion of the molecule ionizes, forming free radical aluminum (Al) This passes freely across cell membranes and forms a physical plug, that when dissolved is selectively absorbed by the liver, kidney, brain, cartilage and bone marrow. It is this concentration of aluminum that has been the source for concern in the medical community, and has prompted the research being done on Alzheimer's disease and Breast Cancer victims. The human body has a few areas that it uses to purge toxins: Behind the knees, ears, groin area and armpits. The toxins are purged in the form of perspiration. Antiperspirant, as the name clearly indicates, prevents you from perspiring, thereby inhibiting the body from purging toxins from below the armpits. These toxins do not magically disappear. Instead the body deposits them in the lymph nodes below the arms since it cannot sweat them out. This causes a high concentration of toxins that leads to cell mutation a.k.a. Cancer. Nearly all Breast Cancer tumors occur in the upper outside quadrant of the breast area. This is where lymph nodes are located. Your best alternative, according to Tia Coatoam a registered nurse at the Meadville, PA Medical Center, is one of the new crystal deodorant stones". These stones are 3 times more effective than commercial deodorants, they are not sticky or greasy and do not stain clothing. The crystal deodorant stone does not contain any aluminum or other harsh chemicals, perfumes, oils, emulsifiers, alcohol or propellants and are hypoallergenic."
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Why do cell membranes have a lipid bilayer instead of a monolayer?
Lipid monolayer vesicles are possible as you mentioned (for example micelles). However, you have to understand that the cellular interior i.e. the cytoplasm, is aqueous and therefore a monolayer vesicle like micelles would not work. In micelles, the two compartments - interior and exterior, have to be of opposite nature for the stability of the micelle. In other words, you cannot have an aqueous environment inside a regular micelle. Conversely, you cannot have a non-polar environment inside an inverse-micelle. Since both the exterior and the interior of a cell are aqueous, both the membrane surfaces have to be hydrophilic. This is possible only in case of a bilayer of usual amphipathic lipids with a hydrophilic head and a hydrophobic tail. However, monolayers are possible in lipids which have two hydrophilic "heads" at both ends and a connecting hydrophobic "torso". Such lipids are found in certain archaea such as Thermoplasma and Ferroplasma, like Miguel mentioned (see this article for more details). As you can notice, these monolayer membranes would be more rigid than bilayers which may be the reason why they evolved in extremophilic archaea. Albers, Sonja-Verena, and Benjamin H. Meyer. "The archaeal cell envelope. " Nature Reviews Microbiology 9. 6 (2011): 414-426.