What is the difference between lipids and phospholipids

They are also found in fats derived from plants. There are many different types of triglycerides, with the main division being between those that contain saturated fatty acids and those that contain unsaturated fatty acids.

In the human bloodstream, triglycerides play an important role in metabolism as energy sources and transporters of dietary fat. They contain more than twice as much energy as carbohydrates, the other major source of energy in the diet. When you eat, your body converts any calories it doesn't need to use right away into triglycerides, which are stored in your fat cells. When you need energy between meals, hormones trigger the release of some of these stored triglycerides back into the bloodstream.

Phospholipids are a major component of the cell membranes of all living things. Each phospholipid molecule has a "tail" consisting of two long fatty acids and a "head" consisting of a phosphate group and glycerol molecule see diagram below. The phosphate group is a small negatively charged molecule. The phospholipid head is hydrophilic or attracted to water. The fatty acid tail of the phospholipid is hydrophobic or repelled by water. These properties allow phospholipids to form a two-layer, or bilayer, cell membrane.

As shown in the diagram below, a phospholipid bilayer forms when many phospholipid molecules line up tail to tail, forming an inner and outer surface of hydrophilic heads.

The hydrophilic heads point toward both the watery extracellular space and the watery intracellular space lumen of the cell. Steroids are lipids with a ring structure.

Each steroid has a core of seventeen carbon atoms arranged in four rings of five or six carbons each see model pictured below. Steroids vary by the other components attached to this four-ring core. Hundreds of steroids are found in plants, animals, and fungi, but most steroids have one of just two principal biological functions: some steroids, such as cholesterol, are important components of cell membranes; many other steroids are hormones, which are messenger molecules.

In humans, steroid hormones include cortisone, a fight-or-flight hormone; and the sex hormones estrogen and testosterone. During a routine checkup with your family doctor, your blood was collected for a lipid profile. Your doctor says this is a little high. Higher levels of triglycerides in the blood have been linked to increased risk of atherosclerosis, heart disease, and stroke. Healthy lifestyle choices to control triglyceride levels include:.

If healthy lifestyle changes aren't enough to bring down high triglyceride levels, drugs prescribed by your doctor are likely to help. Watch the video below to learn more about triglycerides and the difference between saturated and unsaturated fatty acids. Lipids and Fatty Acids Fats are actually a type of lipid.

Saturated Fatty Acids In saturated fatty acids, carbon atoms are bonded to as many hydrogen atoms as possible. Unsaturated Fatty Acids In unsaturated fatty acids , some carbon atoms are not bonded to as many hydrogen atoms as possible. The blue balls, white balls, and red balls represent carbon, hydrogen, and oxygen, respectively.

Saturated fatty acids, such as arachidic, stearic and palmitic, have straight chains. Unsaturated fatty acids have bent chains. Monounsaturated fatty acids, such as erucic and oleic have a single double bond between carbons creating a single bend in the chain. Polyunsaturated fatty acids, such as arachidoic and linoleic, have multiple carbon-carbon double bonds creating multiple bends.

Types of Lipids Lipids may consist of fatty acids alone, or they may contain other molecules as well. Triglycerides Triglycerides are formed by combining a molecule of glycerol with three fatty acid molecules. Explanation: The lipid is a big group of molecules containing carbon, hydrogen and oxygen. Related questions What are lipids? How can fatty acids become phospholipids? Explain saturated fatty acids. Explain how lipids lead to ATP production?

How are fats absorbed and transported by the body? What are some examples of fatty acids? Biological membranes remain fluid because of the unsaturated hydrophobic tails, which prevent phospholipid molecules from packing together and forming a solid.

If a drop of phospholipids is placed in water, the phospholipids spontaneously form a structure known as a micelle, with their hydrophilic heads oriented toward the water. Micelles are lipid molecules that arrange themselves in a spherical form in aqueous solution.

The formation of a micelle is a response to the amphipathic nature of fatty acids, meaning that they contain both hydrophilic and hydrophobic regions. Steroids, like cholesterol, play roles in reproduction, absorption, metabolism regulation, and brain activity. Unlike phospholipids and fats, steroids have a fused ring structure.

Although they do not resemble the other lipids, they are grouped with them because they are also hydrophobic and insoluble in water. All steroids have four linked carbon rings, and many of them, like cholesterol, have a short tail. Many steroids also have the —OH functional group, and these steroids are classified as alcohols called sterols. Steroid Structures : Steroids, such as cholesterol and cortisol, are composed of four fused hydrocarbon rings. Cholesterol is the most common steroid and is mainly synthesized in the liver; it is the precursor to vitamin D.

Cholesterol is also a precursor to many important steroid hormones like estrogen, testosterone, and progesterone, which are secreted by the gonads and endocrine glands.

Cholesterol also plays a role in synthesizing the steroid hormones aldosterone, which is used for osmoregulation, and cortisol, which plays a role in metabolism. Cholesterol is also the precursor to bile salts, which help in the emulsification of fats and their absorption by cells. It is a component of the plasma membrane of animal cells and the phospholipid bilayer. Being the outermost structure in animal cells, the plasma membrane is responsible for the transport of materials and cellular recognition; and it is involved in cell-to-cell communication.

Thus, steroids also play an important role in the structure and function of membranes. It has also been discovered that steroids can be active in the brain where they affect the nervous system, These neurosteroids alter electrical activity in the brain.

They can either activate or tone down receptors that communicate messages from neurotransmitters. Since these neurosteroids can tone down receptors and decrease brain activity, steroids are often used in anesthetic medicines. Privacy Policy. Skip to main content. Biological Macromolecules. Search for:. Lipid Molecules Fats and oils, which may be saturated or unsaturated, can be unhealthy but also serve important functions for plants and animals. Learning Objectives Differentiate between saturated and unsaturated fatty acids.

Key Takeaways Key Points Fats provide energy, insulation, and storage of fatty acids for many organisms. Fats may be saturated having single bonds or unsaturated having double bonds.

Unsaturated fats may be cis hydrogens in same plane or trans hydrogens in two different planes. Olive oil, a monounsaturated fat, has a single double bond whereas canola oil, a polyunsaturated fat, has more than one double bond. Omega-3 fatty acid and omega-6 fatty acid are essential for human biological processes, but they must be ingested in the diet because they cannot be synthesized.

Key Terms hydrogenation : The chemical reaction of hydrogen with another substance, especially with an unsaturated organic compound, and usually under the influence of temperature, pressure and catalysts. It contains the functional group carbon-oxygen double bond joined via carbon to another oxygen atom. OH ; characteristic of carboxylic acids. Waxes Waxes are nonpolar lipids that plants and animals use for protection and have many functions in society.

Learning Objectives Describe the roles played by waxes. Key Takeaways Key Points Natural waxes are typically esters of fatty acids and long chain alcohols. Animal wax esters are derived from a variety of carboxylic acids and fatty alcohols. Plant waxes are derived from mixtures of long-chain hydrocarbons containing functional groups.

Because of their hydrophobic nature, waxes prevent water from sticking on plants and animals. Synthetic waxes are derived from petroleum or polyethylene and consist of long-chain hydrocarbons that lack functional groups.

Synthetic and waxes are used in adhesives, cosmetics, food, and many other commercial products. Key Terms paraffin wax : A waxy white solid hydrocarbon mixture used to make candles, wax paper, lubricants, and sealing materials. Phospholipids Phospholipids are amphipathic molecules that make up the bilayer of the plasma membrane and keep the membrane fluid. Learning Objectives Describe phospholipids and their role in cells. Key Takeaways Key Points Phospholipids consist of a glycerol molecule, two fatty acids, and a phosphate group that is modified by an alcohol.

The phosphate group is the negatively-charged polar head, which is hydrophilic. The fatty acid chains are the uncharged, nonpolar tails, which are hydrophobic. Since the tails are hydrophobic, they face the inside, away from the water and meet in the inner region of the membrane. Since the heads are hydrophilic, they face outward and are attracted to the intracellular and extracellular fluid.

If phospholipids are placed in water, they form into micelles, which are lipid molecules that arrange themselves in a spherical form in aqueous solutions.