How can fats provide an animal with water

Lipids are also the building blocks of many hormones and are an important constituent of all cellular membranes. Lipids include fats, oils, waxes, phospholipids, and steroids.

A fat molecule consists of two main components—glycerol and fatty acids. Glycerol is an organic compound alcohol with three carbons, five hydrogens, and three hydroxyl OH groups. During this ester bond formation, three water molecules are released. The three fatty acids in the triacylglycerol may be similar or dissimilar. Fats are also called triacylglycerols or triglycerides because of their chemical structure. Some fatty acids have common names that specify their origin.

For example, palmitic acid, a saturated fatty acid , is derived from the palm tree. Arachidic acid is derived from Arachis hypogea, the scientific name for groundnuts or peanuts. Fatty acids may be saturated or unsaturated. In a fatty acid chain, if there are only single bonds between neighboring carbons in the hydrocarbon chain, the fatty acid is said to be saturated.

Saturated fatty acids are saturated with hydrogen; in other words, the number of hydrogen atoms attached to the carbon skeleton is maximized. When the hydrocarbon chain contains a double bond, the fatty acid is said to be unsaturated. Most unsaturated fats are liquid at room temperature and are called oils. If there is one double bond in the molecule, then it is known as a monounsaturated fat e. When a fatty acid has no double bonds, it is known as a saturated fatty acid because no more hydrogen may be added to the carbon atoms of the chain.

A fat may contain similar or different fatty acids attached to glycerol. Long straight fatty acids with single bonds tend to get packed tightly and are solid at room temperature. Animal fats with stearic acid and palmitic acid common in meat and the fat with butyric acid common in butter are examples of saturated fats. In plants, fat or oil is stored in many seeds and is used as a source of energy during seedling development.

Unsaturated fats or oils are usually of plant origin and contain cis unsaturated fatty acids. Cis and trans indicate the configuration of the molecule around the double bond. If hydrogens are present in the same plane, it is referred to as a cis fat; if the hydrogen atoms are on two different planes, it is referred to as a trans fat.

Olive oil, corn oil, canola oil, and cod liver oil are examples of unsaturated fats. Lipids are a diverse group of compounds that are united by a common feature.

Lipids perform many different functions in a cell. Cells store energy for long-term use in the form of lipids called fats. Lipids also provide insulation from the environment for plants and animals. For example, they help keep aquatic birds and mammals dry because of their water-repelling nature. Lipids are also the building blocks of many hormones and are an important constituent of the plasma membrane.

Lipids include fats, oils, waxes, phospholipids, and steroids. A fat molecule consists of two main components—glycerol and fatty acids. Glycerol is an organic compound an alcohol that contains three carbons, five hydrogens, and three hydroxyl OH groups. In a fat molecule, the fatty acids are attached to each of the three carbons of the glycerol molecule with a covalent bond.

This molecule is called a triglyceride. Wax covers the feathers of some aquatic birds and the leaf surfaces of some plants. Because of the hydrophobic nature of waxes, they prevent water from sticking on the surface Figure 5. Waxes are made up of long fatty acid chains covalently bonded to long-chain alcohols.

Lipids comprise waxy coverings on some leaves. Like fats, they are comprised of fatty acid chains attached to a glycerol or sphingosine backbone. A phosphate group alone attached to a diaglycerol does not qualify as a phospholipid. It is phosphatidate diacylglycerol 3-phosphate , the precursor of phospholipids.

An alcohol modifies the phosphate group. Phosphatidylcholine and phosphatidylserine are two important phospholipids that are in plasma membranes. Figure 8. 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. A phospholipid is an amphipathic molecule, meaning it has a hydrophobic and a hydrophilic part. The fatty acid chains are hydrophobic and cannot interact with water; whereas, the phosphate-containing group is hydrophilic and interacts with water Figure. Figure 9. 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. The head is the hydrophilic part, and the tail contains the hydrophobic fatty acids.

Unlike the phospholipids and fats that we discussed earlier, steroids have a fused ring structure. Although they do not resemble the other lipids, scientists group them with them because they are also hydrophobic and insoluble in water. All steroids have four linked carbon rings and several of them, like cholesterol, have a short tail Figure.

Many steroids also have the —OH functional group, which puts them in the alcohol classification sterols. Figure Four fused hydrocarbon rings comprise steroids such as cholesterol and cortisol. Cholesterol is the most common steroid. The liver synthesizes cholesterol and is the precursor to many steroid hormones such as testosterone and estradiol, which gonads and endocrine glands secrete.

It is also the precursor to Vitamin D. Cholesterol is also the precursor of bile salts, which help emulsifying fats and their subsequent absorption by cells. Sterols cholesterol in animal cells, phytosterol in plants are components of the plasma membrane of cells and are found within the phospholipid bilayer.

Lipids are a class of macromolecules that are nonpolar and hydrophobic in nature. Major types include fats and oils, waxes, phospholipids, and steroids. Fats are a stored form of energy and are also known as triacylglycerols or triglycerides.

Fats are comprised of fatty acids and either glycerol or sphingosine. Fatty acids may be unsaturated or saturated, depending on the presence or absence of double bonds in the hydrocarbon chain. If only single bonds are present, they are saturated fatty acids. Unsaturated fatty acids may have one or more double bonds in the hydrocarbon chain. They have a glycerol or sphingosine backbone to which two fatty acid chains and a phosphate-containing group are attached.

Steroids are another class of lipids. Their basic structure has four fused carbon rings. 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.

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.