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Viscosity of the membrane can affect the rotation and diffusion of proteins and other bio-molecules within the membrane, there-by affecting the functions of these things. [1] Membrane fluidity is affected by fatty acids. More specifically, whether the fatty acids are saturated or unsaturated has an effect on membrane fluidity.
Membrane lipids are a group of compounds (structurally similar to fats and oils) which form the lipid bilayer of the cell membrane. The three major classes of membrane lipids are phospholipids, glycolipids, and cholesterol. Lipids are amphiphilic: they have one end that is soluble in water ('polar') and an ending that is soluble in fat ...
This fatty acid composition results in a more fluid cell membrane but also one that is permeable to various ions (H+ & Na+), resulting in cell membranes that are more costly to maintain. This maintenance cost has been argued to be one of the key causes for the high metabolic rates and concomitant warm-bloodedness of mammals and birds. [9]
The effect of this is that, in restricted environments, such as when fatty acids are part of a phospholipid in a lipid bilayer or triglycerides in lipid droplets, cis bonds limit the ability of fatty acids to be closely packed, and therefore can affect the melting temperature of the membrane or of the fat. Cis unsaturated fatty acids, however ...
The general trend is an increase in unsaturated fatty acids at lower growth temperatures and an increase in saturated fatty acids at higher temperatures. A recent work has explored the importance of the homeoviscous adaptation of the cell membrane for a psychrotolerant bacteria living in the cold biosphere of earth.
Integral membrane proteins function when incorporated into a lipid bilayer, and they are held tightly to the lipid bilayer with the help of an annular lipid shell. Because bilayers define the boundaries of the cell and its compartments, these membrane proteins are involved in many intra- and inter-cellular signaling processes.
These organisms maintain a constant fluidity by modifying membrane lipid fatty acid composition in accordance with differing temperatures. [6] In animal cells, membrane fluidity is modulated by the inclusion of the sterol cholesterol. This molecule is present in especially large amounts in the plasma membrane, where it constitutes approximately ...
For example, in humans, the desaturation of stearic acid by stearoyl-CoA desaturase-1 produces oleic acid. The doubly unsaturated fatty acid linoleic acid as well as the triply unsaturated α-linolenic acid cannot be synthesized in mammalian tissues, and are therefore essential fatty acids and must be obtained from the diet. [2]: 643