Monica Olvera de la Cruz stated the fact that “in nature, living things function at a delicate balance: acidity, temperature, all its surroundings must be within specific limits, or they die,”. She set out to test those very limits, specifically how bi-layer crystallization changes when exposed to different pH levels. It was examined through an electron microscope that most molecules didn't respond to the change in acidity. But those that did saw a change in the crystal shape of the hydrophilic heads, and it was drastic - from a rectangular figure to a hexagonal figure. Shells with higher symmetry (hexagonal) are more rigid and less brittle, which was a huge discovery. Not only does the change in pH affect the rigidity of the outer layer, it alters the thickness of the membrane as well. These discoveries could help scientists control the encapsulation and release efficiency of molecules inside a vesicle.
What happens when there is a problem with the cell membrane’s ability to uptake/export important molecules or communicate?
There are many diseases associated with problems in the ability of the phospholipid bilayer to perform these functions. One of these is Alzheimer’s disease, characterized by brain shrinkage and memory loss. One idea explaining why Alzheimer’s disease occurs is the forming of plaque sticking to the phospholipid bilayer of the brain neurons. These plaques block communication between the brain neurons, eventually leading to neuron death and in turn causing the symptoms of Alzheimer’s, such as poor short-term memory.
Researchers further revealed how protease embedded in cellular membranes hydrolyse other proteins which results in the capability of the breaking protein to transmit signals. Peptide bonds that result from the bonding of amino acids within a protein are very stable and the hydrolysis process is not easy. Here, proteases come into play: they interact with their substrates allowing them to reduce their activation energy allowing hydrolysis of peptide bonds within milliseconds that without this catalysis would take hundreds of years and life wouldn’t be possible. The cell membrane is mainly composed of lipids but also contains protein. They span the membrane with domains that are mainly composed of amino acids that allow interaction with lipids. These proteins are called integral membrane proteins. The breakdown of protein requires proteases since they are the only players in a cell capable of hydrolysing peptide bonds. During this process the intramembrane don’t only initiate the break down but also produce protein fragments that are capable of transmitting signals across membranes. This can contribute to proper immune system functions.
Breast cancer is a highly prevalent disease as it accounts for the second highest number of cancer related mortalities worldwide. There is a potent chemotherapeutic drug called Anthracycline Doxorubicin, or DOX for short, that is successfully used to treat various forms of liquid and solid tumors and is currently approved to treat breast cancer. It kills the cancers cells by passive diffusion through the phospholipid bilayer membrane of malignant cells into the cytoplasm. In the cytosol, DOX enters the mitochondria causing DNA damage and energetic stress. As a result, the mitochondria release the cytochrome Cprotein and triggering cell death.
A cell is the basic unit of life, and all organisms are made up of one or many cells. One of the things that all cells have in common is a cell membrane. It is a barrier that separates a cell from its surrounding environment. Phospholipids make up the basic structure of a cell membrane. A single phospholipid molecule has two different ends: a head and a tail. The head end contains a phosphate group and is hydrophilic. This means that it likes or is attracted to water molecules. The tail end is made up of two strings of hydrogen and carbon atoms called fatty acid chains. These chains are hydrophobic. Cholesterol molecules are important for maintaining the consistency of the cell membrane. They strengthen the membrane by preventing some small molecules from crossing it. Cholesterol molecules also keep the phospholipid tails from coming into contact and solidifying. This ensures that the cell membrane stays fluid and flexible.
Researchers have developed models of bacterial outer membranes that can help create better antibiotics that fight some of the antibiotic-resistant bacteria in our bodies. The the study of the cell membrane is important in over sixty-percent of currently available drugs and forty-percent of new drugs which target membrane proteins so that the antibiotics attack the lipid-bilayer components of bacterial membranes. They use a technique called neutron reflectometry that provides info on membrane proteins by slicing through the depth of the membrane including info on the thickness and distribution of different components (lipids, proteins and water) in the bilayer.
Our body encounters many foreign tissues and cells every single day. These foreign bodies can harm us and they systems within us. The immune cells in our body destroy these foreign bodies, but how are they able to tell foreign bodies apart from our important cells? This is done by the cell membrane. The cell membrane of a cell contains specific markers. These markers are more like cellular ID cards which are used by cells to recognize each other. These markers are extremely important from the perspective of our immune system. The only way immune cells can tell important bodies apart from foreign is from these markers which allows for them to selectively destroy the foreign bodies and protect the important bodies.
Green tea has been linked to weight loss and prevention of many diseases and just recently, scientists have discovered an antioxidant called epigallocatechin gallate (EGCG) in green tea that can sneak therapeutic RNAs into cells. Specific RNAs (siRNAs) have the potential to prevent diseases caused by genes by dialing down the expression however they have a difficult time getting through the cell membrane. The cell membrane is composed of a phospholipid bilayer (hydrophilic heads and hydrophobic tails) that surrounds cells to separate the interior of a cell from the exterior environment. It is selectively permeable and controls what leaves and enters the cell. siRNAs are large and negatively charged therefore making it difficult for them to enter the cell. Researchers have tried coating them with polymers but this approach hasn’t been effective. EGCG has the ability to help these RNAs enter the cell membrane.
New 3D maps of water distribution during cellular membrane fusion are increasing scientific understanding of cell development, which could lead to new treatments for diseases associated with cell fusion. Using neutron diffraction at the Department of Energy's Oak Ridge National Laboratory, researchers have made observations of water in lipid bilayers used to model cell membrane fusion. The research could provide new insights on diseases where normal cell fusion is disrupted and it can help the development of fusion-based cell therapies for degenerative diseases. This can lead to treatments that prevent cell-to-cell fusion between cancer cells and non-cancer cells.
The cell membrane’s main job is to serve as a barrier between the cell and the world; so the cell needs to have a structure which allows it to interact with both. A cell’s membrane is primarily made up of a double layer of phospholipids. Each layer is composed of phospholipid molecules that contain a hydrophilic (water-loving) head and a hydrophobic (water-repellent) tail. The heads in the outermost layer face and interact with the watery external environment, while the heads of those in the interior layer point inward and interact with the cell’s watery cytoplasm. The region between the two layers is fluid repellent, which has the effect of separating the inside of the cell from the outside world. The cell membrane is semipermeable, which allows selected molecules to pass into or out of the cell.
This website explains some interesting facts about the cell membrane. For example, when there is a drop in temperature, the tails that are made of saturated fatty acids will pack in tightly, making a dense and rigid membrane but those phospholipids that have a combination of saturated and unsaturated fatty acid tails will fail to make such a dense packing because of the bends present in the unsaturated fatty acid tails. So, even when temperature drops, the cell membranes that have unsaturated fatty acids in them will remain pretty fluid.
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