Triglycerides Triglycerides are formed by combining a molecule of glycerol with three fatty acid molecules. The left part of this triglyceride molecule represents glycerol. Each of the three long chains on the right represents a different fatty acid.
From top to bottom, the fatty acids are palmitic acid, oleic acid, and alpha-linolenic acid. Phospholipids Phospholipids are a major component of the cell membranes of all living things. 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. Steroids Steroids are lipids with a ring structure. The red balls are representing oxygen and the white balls are representing hydrogen in the model.
The components of the molecule may vary and determine the steroid's function. Feature: My Human Body During a routine checkup with your family doctor, your blood was collected for a lipid profile.
Healthy lifestyle choices to control triglyceride levels include: losing weight. If you are overweight, losing even 5 or 10 pounds may help lower your triglyceride level. Extra calories are converted to triglycerides and stored as fat, so reducing your calories should also reduce your triglyceride level. Simple carbohydrates, such as sugars and foods made with white flour, can increase triglyceride levels.
Trade saturated fats found in animal foods for healthier unsaturated fats found in plants and oily fish. For example, substitute olive oil for butter and salmon for red meat. Alcohol is high in calories and sugar and has a strong effect on triglyceride levels. Aim for at least 30 minutes of physical activity on most or all days of the week to lower triglyceride levels. Review What are lipids? Compare and contrast saturated and unsaturated fatty acids. Identify three major types of lipids, and describe differences in their structures.
How do triglycerides play an important role in human metabolism? Explain how phospholipids form cell membranes. What is cholesterol, and what is its major function? Give three examples of steroid hormones in humans. Register or login to make commenting easier. Save my name, email, and website in this browser for the next time I comment. Toggle navigation. Search Log In.
Phospholipids and Steroids. To do 4 min read 7 min video. Phospholipids Phospholipids are major constituents of the plasma membrane, the outermost layer of animal cells.
Share Thoughts. Summarizing Lipids. Share Thoughts Post Image. Cancel Reply. Add Math. Math Editor. Edit math using TeX:. Math preview:. Cortisol is a small, generally hydrophobic molecule, while the phospholipids that create plasma membranes have a hydrophilic head and hydrophobic tails. Since cortisol is hydrophobic, it can interact with the sequestered tails of the phospholipids in the center of the plasma membrane.
This, along with its small size, allows cortisol to move through the plasma membrane to the inside of the cell. Skip to content Biological Macromolecules. Fats and Oils A fat molecule consists of two main components—glycerol and fatty acids.
Joining three fatty acids to a glycerol backbone in a dehydration reaction forms triacylglycerol. Three water molecules release in the process. Stearic acid is a common saturated fatty acid.
Oleic acid is a common unsaturated fatty acid. Saturated fatty acids have hydrocarbon chains connected by single bonds only.
Unsaturated fatty acids have one or more double bonds. Each double bond may be in a cis or trans configuration. In the cis configuration, both hydrogens are on the same side of the hydrocarbon chain. In the trans configuration, the hydrogens are on opposite sides.
A cis double bond causes a kink in the chain. Trans Fats The food industry artificially hydrogenates oils to make them semi-solid and of a consistency desirable for many processed food products. Omega Fatty Acids Essential fatty acids are those that the human body requires but does not synthesize. Alpha-linolenic acid is an example of an omega-3 fatty acid. It has three cis double bonds and, as a result, a curved shape.
For clarity, the diagram does not show the carbons. Each singly bonded carbon has two hydrogens associated with it, which the diagram also does not show. Lipids comprise waxy coverings on some leaves. A phospholipid is a molecule with two fatty acids and a modified phosphate group attached to a glycerol backbone. Adding a charged or polar chemical group may modify the phosphate. The phospholipid bilayer is the major component of all cellular membranes.
The hydrophilic head groups of the phospholipids face the aqueous solution. The hydrophobic tails are sequestered in the middle of the bilayer. Steroids Unlike the phospholipids and fats that we discussed earlier, steroids have a fused ring structure. Four fused hydrocarbon rings comprise steroids such as cholesterol and cortisol. Link to Learning. Section Summary Lipids are a class of macromolecules that are nonpolar and hydrophobic in nature.
Review Questions Saturated fats have all of the following characteristics except: they are solid at room temperature they have single bonds within the carbon chain they are usually obtained from animal sources they tend to dissolve in water easily. Unlike most natural waxes, which are esters, synthetic waxes consist of long-chain hydrocarbons lacking functional groups. Paraffin wax is a type of synthetic wax derived from petroleum and refined by vacuum distillation.
Synthetic waxes may also be obtained from polyethylene. Millions of of these waxes are produced annually, and they are used in adhesives, cosmetics, sealants and lubricants, insecticides, and UV protection. They are also used in foods like chewing gum. Generic structure formula of bee waxes : Ester myricyl palmitate is a major component of beeswax.
Phospholipids are amphipathic molecules that make up the bilayer of the plasma membrane and keep the membrane fluid. Phospholipids are major components of the plasma membrane, the outermost layer of animal cells. Like fats, they are composed of fatty acid chains attached to a glycerol backbone.
Unlike triglycerides, which have three fatty acids, phospholipids have two fatty acids that help form a diacylglycerol. The third carbon of the glycerol backbone is also occupied by a modified phosphate group. However, just a phosphate group attached to a diacylglycerol does not qualify as a phospholipid. This would be considered a phosphatidate diacylglycerol 3-phosphate , the precursor to phospholipids. To qualify as a phospholipid, the phosphate group should be modified by an alcohol.
Phosphatidylcholine and phosphatidylserine are examples of two important phospholipids that are found in plasma membranes. Phospholipid Molecule : A phospholipid is a molecule with two fatty acids and a modified phosphate group attached to a glycerol backbone.
The phosphate may be modified by the addition of charged or polar chemical groups. Two chemical groups that may modify the phosphate, choline and serine, are shown here. Both choline and serine attach to the phosphate group at the position labeled R via the hydroxyl group indicated in green.
A phospholipid is an amphipathic molecule which means it has both a hydrophobic and a hydrophilic component. Some lipid tails consist of saturated fatty acids and some contain unsaturated fatty acids. This combination adds to the fluidity of the tails that are constantly in motion.
The cell membrane consists of two adjacent layers of phospholipids, which form a bilayer. The fatty acid tails of phospholipids face inside, away from water, whereas the phosphate heads face the outward aqueous side.
Since the heads face outward, one layer is exposed to the interior of the cell and one layer is exposed to the exterior. As the phosphate groups are polar and hydrophilic, they are attracted to water in the intracellular fluid. Phospholipid Bilayer : The 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.
As a result, there are two distinct aqueous compartments on each side of the membrane. This separation is essential for many biological functions, including cell communication and metabolism. 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.
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