We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What are Membrane Lipids?

By Victoria Blackburn
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Membrane lipids are integral for active transport across the membrane, many types of enzyme activity and membrane formation. Lipids are a group of compounds that include fats and oils and are insoluble in water, but soluble in alcohol. In other words, lipids do not dissolve in water, which is clearly shown when you add oil to water – they mix, but remain separate. There are many different types of lipids, but the major classes of membrane lipids are phospholipids, glycolipids, sphingolipids and cholesterol.

Lipids are amphipathic because each molecule has two distinct areas with different affinities for water and oil. The hydrophilic area of the molecule is polar, so it is attracted to water. The hydrophobic region is not polar and will not dissolve in water. It is this distinct characteristic of lipids that causes the structure of living membranes. When a membrane is formed, the membrane lipids arrange into a bilayer. A bilayer is made up of two sheets of membrane lipids with their hydrophilic heads pointing out and hydrophobic tails in the middle of the membrane bilayer.

All membranes in living organisms, both around the cells and within them, are mostly made up lipids and proteins. The membrane lipids are the most predominant molecules in the membrane. Some proteins are interspersed throughout the lipid layer, while others are attached to its surface.

Most membrane lipids are formed from glycerol linking to three fatty acid chains through covalent bonding. The resulting molecules are called glycerides. Sphingolipids are the exception to this rule as they are formed when sphingosine covalently bonds to the fatty acid chains instead of the glycerol. Covalent bonding occurs when oppositely charged atoms share electron pairs.

Phospholipids are the most common of the membrane lipids. They are formed when a phosphate group, which contains phosphorous, is bonded to a diglyceride and another simple organic molecule. A diglyceride is made up from two glyceride molecules. In a phospholipid, the head containing the phosphate group is polar, so it is attracted to water. The long hydrocarbon chains of the fatty acids are hydrophobic and stay in the middle of the membrane bilayer.

Glycolipids are formed when a carbohydrate chain attaches to a phospholipid. The carbohydrate chain is found on the outside layer of the membrane bilayer. This way, the carbohydrate chain acts as a marker to allow cellular recognition. Also, glycolipids provide energy, which is stored in the carbohydrate chain. Finally, glycolipids help stabilize the membrane and provide a place for attaching to other cells or tissues.

When cholesterol is present in a membrane, it binds weakly with phospholipids on either side of it. By binding to the adjacent phospholipids, the cholesterol stabilizes them and in turn stabilizes the entire membrane. With greater amounts of cholesterol, the membrane becomes less fluid, or able to move freely, and more mechanically stronger. The amount of cholesterol found in membranes varies due to cell type. Plants contain no cholesterol, so rely on the cell wall for stability of their cells.

Finally, sphingolipids are found mostly in the outer layer of the bilayer. There is a very uneven distribution of this type of lipid across the bilayer. Sphingolipids form lipid rafts, which are important in cell signalling and recognition. Cholesterol is sometimes found beside or near the sphingolipids to stabilize the cell membrane around them.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.