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How is it that changes in membrane fluidity can lead to tumor development?

How is it that changes in membrane fluidity can lead to tumor development?

Alterations in membrane fluidity can seriously affect functional properties of the cell and may cause the induction of apoptotic pathways resulting in cell death. We hypothesized that the resistant phenotype of the tumor cells is, in large part, regulated by the fluidity of the tumor cell membranes.

Where is cholesterol found in cell membranes?

Cholesterol, another lipid composed of four fused carbon rings, is found alongside phospholipids in the core of the membrane. Membrane proteins may extend partway into the plasma membrane, cross the membrane entirely, or be loosely attached to its inside or outside face.

How does cell regulate cholesterol level?

Cells regulate the synthesis of cholesterol by controlling the amount of HMG-CoA. When cholesterol levels are high, cells reduce the amount of HMG-CoA. Elevated cellular cholesterol and its precursors activate proteins that extract HMG-CoA from the ER membrane and move it into the cytosol.

How does cholesterol enter the cell?

Most cholesterol is transported in the blood as cholesteryl esters in the form of lipid-protein particles known as low-density lipoproteins (LDL) (Figure 13-43). When a cell needs cholesterol for membrane synthesis, it makes transmembrane receptor proteins for LDL and inserts them into its plasma membrane.

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How plasma membranes are arranged in the presence of water?

In the phospholipid bilayer of the plasma membrane, the phospholipid layers are arranged so that the two phosphate hydrophilic regions face outward, towards the watery extracellular environment, and inward, towards the cellular cytoplasm, which also contains water.

Why is the plasma membrane a bilayer?

The structure is called a “lipid bilayer” because it is composed of two layers of fat cells organized in two sheets. The lipid bilayer is typically about five nanometers thick and surrounds all cells providing the cell membrane structure.

Where is the phospholipid bilayer?

Phospholipid BilayerThe phospholipid bilayer consists of two adjacent sheets of phospholipids, arranged tail to tail. The hydrophobic tails associate with one another, forming the interior of the membrane. The polar heads contact the fluid inside and outside of the cell.

Why is the lipid bilayer asymmetry?

Lipid asymmetry in membranes is a consequence of multiple factors, including the biophysical properties of lipids that dictate their ability to spontaneously “flip” their polar headgroups through the hydrophobic membrane interior, and the presence of transporters (enzymes) that assist in active lipid translocation …

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Why do phospholipids rarely flip flop?

This is because the polar region of the molecule must actually make its way through the hydrophobic core of the membrane. In the case of the protein, the polar region is so extensive that the protein does not flip flop at all. Phospholipids have smaller polar regions and so can occasionally flip flop.