Which membrane gives eukaryotes an advantage over prokaryotes in protecting genetic matieral from damaging....
821161
Nuclear?  Nuclear envelope?  Nuclear membrane? \n\nThe word 'eukaryote' means 'true nuclei'.  They are talking about the membrane which surrounds the nucleus of the cell.  This is not present in Prokaryotes.
6888
First off jamesmusik84's is completely wrong. Please don't consider any of it. The second answer is along the right path, except I have no idea what the reference to antibiotic is suggesting and some viruses have RNA genomes but many more have DNA genomes. And as far as bacteria go, both RNA and DNA are present inside there cells.\n\nSo, the answer to your question. Let's start this way: Bacteria are small single-celled organisms. Unllike eukaryotic cells (like the ones that make up animals, plants, fungi and many single-celled organisms such as yeasts) which package their genetic material (DNA) in membrane structures called nuclei, bacteria (which are also referred to as prokaryotes) don't have a nucleus. Bacteria also don't have other organelles which are found in eukaryotes, such as endoplasmic reticulum, mitochandria, chloroplasts, golgi bodies, etc. But like eukaryotes, bacteria do have an outer lipid membrane.\n\nSo, you can think of bacteria of little fluid filled sacs. Along with eukaryotic, bacteria are an example of "cells" which are the smallest unit of living things on earth.\n\nViruses, on the other hand, do not have an outer membrane. They don't the capacity to make their own proteins. They don't have the capacity ot replicate or metabolize on their own -- of which bacteria (and eukaryotes) do. It's for this reason that we don't consider viruses "living" things. Viruses have to "infect" a cell -- injecting its genetic material inside -- and use the cell's metabolic machinery to reproduce.\n\nViruses are essentially small protein "capsules" that have a piece of genetic information packaged inside. Because viruses are required to infect a cell to propogate themselves, they are classified as obligate intra-cellular pathogens.\n\nViruses tend to only infect specific cell types. Some infect bacteria. Some infect plants. Others infect animals. The specificity of what a virus can infect is goes beyond whether they can infect bacteria, plants or animals. Usually viruses have to infect a very specific animal, plant or bacteria. And even in the case of viruses that infect animals and plants, not only do the infect specif animals, they are usually limited to a few cell types whithin that animal.\n\nTake HIV for example: to the best of my knowledge HIV only infects humans (i.e. the "H" in HIV -- Human Immunodeficiency Virus). But it doesn't just infect any human cell. HIV only infects white blood cells -- specifically a class of white blood cells called T cells (there are many other "classes" of white blood cells including such things as B cells, NK cells, neutrophils, basophils, eosinophils and macrophages).\n\nI hope this sheds some light on the matter.
769432
Eukaryotic...Prokaryotic are bacteria cells...Hope it helps!
246458
The cell membrane is made up of a phospholipid bilayer, with a polar phophate head and a nonpolar lipid tail. The polar head is hydrophilic, the nonpolar tail is hydrophobic. A fat molecule will face toward the nonpolar, hydrophobic tail.
727221
Eukaryotic cells have a definite nucleus, membrane bound organelles, usually larger in size (when compared to a prokaryotic cell), and certain eukaryotes are multicellular.\n\nProkaryotic cells do not have a definite nucleus, do not have membrane bound organelles, are much smaller in size (when compared to a eukaryotic cell), and are single celled.
771971
Cell membrane, or phospholipid bi-layer.
107742
To combat free radicals\n-----------------\nIn biological systems, the normal processes of oxidation (plus a minor contribution from ionizing radiation) produce highly reactive free radicals. These can readily react with and damage other molecules. In some cases the body uses free radicals to destroy foreign or unwanted objects, such as in an infection. However, in the wrong place, the body's own cells may become damaged. Should the damage occur to DNA, the result could be cancer. Antioxidants decrease the damage done to cells by reducing oxidants before they can damage the cell.\n\nVirtually all studies of mammals have concluded that a restricted calorie diet extends the lifespan of mammals by as much as 100%. This remarkable finding suggests that food is actually more damaging than smoking. As food produces free radicals (oxidants) when metabolized, antioxidant-rich diets are thought to stave off the effects of aging significantly better than diets lacking in antioxidants. The reduced levels of free radicals, resulting from a reduction in their production by metabolism, is thought to be a major cause of the success of caloric restriction in increasing life span.\n\nFree radical damage in the mitochondria of living cells is a byproduct of oxidative phosphorylation. Superoxide radicals are generated, which can damage mitochodrial and mitochondrial membranes. Unlike DNA in the cell nucleus, mitochondrial DNA has only a few DNA-repair enzymes and the DNA is not protected by histones.\n\nMany antioxidants, however (including vitamin C and vitamin E) can't get into mitochondria for various reasons (e.g. because they are too hydrophilic to cross mitochondrial membranes or too hydrophobic to cross the cytoplasm). Melatonin is an important natural antioxidant that has been demonstrated [citation needed] to strongly protect mitochondria from damage. A group of scientists in Russia (led by V. Skulachev) have created a custom antioxidant (a Skulachev ion forms the point of the molecule and penetrates the mitochondrial membrane; the antioxidising part is attached behind it) that can enter the mitochondria and stays there due to the membrane potential gradient; preventing damage to DNA.\n\nAlthough there is little doubt that antioxidants are a necessary component for good health, there is considerable doubt as to the most beneficial antioxidant(s) and as to the optimal amount for results. A study of lung cancer patients found that those given antioxidant supplements had worse prognoses. This is believed to be due to antioxidant interference with the body's normal use of localised free radicals e.g. Nitric oxide for cell signalling. Due to the complex nature of the interactions of antioxidants with the body, it is difficult to interpret the results of many experiments designed to test such things. In vitro testing (outside the body) has shown many natural antioxidants, in specific concentration, can halt the growth of or even kill cancerous cells.\n\nFor example, recent studies are suggesting that at high levels, synthetic antioxidant vitamins such as A, E and C may prove to have pro-oxidant effects: increasing the formation of free radicals. The fact that natural antioxidants are always ingested together with a wide variety of flavonoids and other phytochemicals also likely plays a part. Many supplement manufacturers supply more expensive tablets containing these. Newer liquid nutritional supplements using plant ionic compounds are believed to be more readily absorbed in the human body.\n\nThe benefits of antioxidants were examined during the Age-Related Eye Disease Study.\n\nNutritional antioxidants\nThe following substances have shown positive antioxidant effects:\n\nVitamin A (Retinol, also synthesized by the body from beta-carotene) protects dark green, yellow and orange vegetables and fruits from solar radiation damage, and is thought to play a similar role in the human body. Carrots, squash, broccoli, sweet potatoes, tom
902276
They are called eukaryotic cells.
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Eukaryotic cells (typical plant and animal cells) are considered to be more advanced than prokayotic cells. Their DNA is contained within a membrane bound nucleus and they contain membrane bound organelles such as mitochondria. They also contain a cytoskeleton which is a series of tubes and microfilaments which are involved with movement within the cell.\n\nProkaryotic cells (eg. bacteria) have no membrane bound nucleus - their DNA is restricted to a region called the nuceoid which is not membrane bound. They contain no membrane bound organelles and have no cytoskeleton. They do contain non membrane bound organelles such as ribosomes ( eukaryotes also contain these)\n\nHope this is of some help.
80564
Procaryotes and eucaryotes are types of microorganisms which are classified based on their membranes.  The main difference between procaryotic and eucaryotic microorganism is that the latter has nucleus and membrane-bound organelles while the former does not.  Furthermore, procaryotes are mostly unicellular while eucaryotes are multicellular.
791085
The cell membrane is a phospholipid bilayer, meaning there are two chains. Each chain has a serious of long non-polar tails (hydrophobic, hate water, non-permeable to polar molecules) with polar heads (hydrophilic, love water, permeable to polar molecules). The polar heads are on the outside of the membrane and the non-polar tails face the middle of the membrane. This structure prevents molecules from freely moving across the membrane. Embedded within the membrane are protein channels that are designed to specifically allow certain molecules through. Some of these channels open randomly, others require some kind of signal. They are selective by allowing molecules of certain size and/or charge (positive or negative) cross the membrane, also keeping in mind concentration gradients (molecules will move down their gradients). In some cases, molecules move against their gradients, but require energy to do it.
427095
prokaryotes have 70S ribosomes, each consisting of a (small) 30S and a (large) 50S subunit, whereas eukaryotes have 80S ribosomes, each consisting of a (small) 40S and a bound (large) 60S subunit. However, the ribosomes found in chloroplasts and mitochondria of eukaryotes are 70S, this being but one of the observations supporting the endosymbiotic theory.\nwhat do you mean by inclusive? Subspecies ?
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Okay this is a bit of a complicated question, but i'll do my best, in short these are really very different things.\n\nFirst cell membranes are found in all cells (animal, plant, fungi etc.) they are made up of lipids, generally as a bilayer.  take the membrane from around the outside of a eukaryotic cell, its formed from phospolipids - these molecules have a hydrophilic head [ie will disolve in water/ has a charge] (the phosphate bit) and a hydrophobic tail (the lipid (fat) bit). The hydrophobic bits stick together and the hydrophilic bits are open to the solution on each side (search "lipid bilayer" with yahoo! Images if you want a diagram:-) ).  The outer cell membrane is forming a barrier between the inside and outside of the cell, alowing the cell to control the movment of molecules into and out of itself.  There are a lot of other membranes in the cell apart from the outher cell membrane, the endoplasmic reticulum for example is basicly made up of membrane.\n\nThe cell wall on the other hand isn't present in all cells (we humans (along with all other animals) don't get one). The cell wall is present on the extracellular side of the outer cell membrane.  it is hard and ridgid (unlike the membrane that is fluid) it is made up of lond polymers, and serves to protect the cell.  Plant cell walls are made up of mainly cellulose (in fact when you look at a peice of wood all you are really seeing is the leftover cell walls, and the rest of the cell has long gone).  Fungi also have cell walls but this time not made of cellulose but instead made of chitin, the cell wall still serves the same role however.\n\nIn short the membrane lets the cell control what goes in and out,  and the cell wall provides rigidity.  Membranes are made of lipids (fats) and cell walls of long polemers like chitin and cellulose.\n\nI hope this helps to answer your question, and look for some diagrams - it will make it a lot easier.
778955
The cell membrane is a lipid bilayer made from phospholipids.  As a lipid, it is permeable to other lipids (e.g. steroid hormones) but not to polar molecules (e.g. potassium or glucose).  Polar molecules require various types of membrane proteins (e.g. potassium channels) or endocytosis (glucose) for absorption into the cell.  \n\nHope this is helpful for you.  Best wishes and good luck.
967476
CELL MEMBRANE IS THE BOUNDARY BETWEEN IT'S CELL AND IT ENVIRONMENT
684160
It depends on the cell... in Eukaryotes a nucleus and nuclear membrane (or "Envelope") are present in non-mitosis or meiosis cell stages. In Prokaryotes there isn't a nucleus or nuclear membrane.
138875
hes wrong (above. Prokaryotes do have organelles. THey do not have membrane bound organelles. Take for example the central vacuole of a plant. It has a membrane surrounding it, so it is not a prokaryote. Prokaryotes have ribosomes which synthesize proteins and nucleic acids to form a polypeptide chain. THey have a mitochondria for ATP etc..