Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Lipid shopping experience:

1. Compare - without doubt the biggest advantage that the Lipid offers shoppers today is the ability to compare thousands of Lipid at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Lipid? Wrong! If the Lipid is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Lipid then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Lipid? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Lipid and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Lipid wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Lipid then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Lipid site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Lipid, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Lipid, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

and cholesterol. In the middle is a triglyceride composed of oleate, stearate, and palmitate chains attached to a glycerol backbone. At the bottom is the common phospholipid phosphatidylcholine. Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including triglyceride, diglyceride, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing metabolites such as cholesterol.

Lipids have many functions in living organisms including nutrients, energy storage, structural components of cell membranes, and important lipid signaling. Although the term lipid is sometimes used as a synonym for fat, fats are in fact a subgroup of lipids called triglycerides and should not be confused with the term fatty acid.

Fatty acids and glycerides Chemically, fatty acids can be described as long-chain monocarboxylic acids the saturated examples of which have a general structure of CH3(CH2)nCOOH. The length of the chain usually ranges from 12 to 24, always with an even number of carbon atoms. When the carbon chain contains no double bonds, it is a saturated chain. If it contains one or more such bonds, it is unsaturated. The presence of double bonds reduces the melting point of fatty acids. Furthermore, unsaturated fatty acids can occur either in cis or trans geometric isomerism. In naturally occurring fatty acids, the double bonds are in the cis-configuration.

Glycerides are lipids possessing a glycerol (another name for which is propan-1, 2, 3-triol) core structure with one or more fatty acyl groups, which are fatty acid-derived chains attached to the glycerol backbone by ester linkages. Glycerides with three acyl groups (triglycerides or neutral fats) are the main form of fatty energy storage in animals and plants.

An important type of glyceride-based molecule found in biological membranes, such as the cell's plasma membrane and the intracellular membranes of organelles, are the phosphoglycerides or glycerophospholipids. These are phospholipids that contain a glycerol core linked to two fatty acid-derived "tails" by ester or, more rarely, ether linkages and to one "head" group by a phosphate ester linkage. The head groups of the phospholipids found in biological membranes are phosphatidylcholine (also known as PC, and lecithin), phosphatidylethanolamine (PE), phosphatidylserine and phosphatidylinositol (PI). These phospholipids are subject to a variety of functions in the cell: for instance, the lipophilic and polar ends can be released from particular phospholipids through enzyme-catalysed hydrolysis to generate secondary messengers involved in signal transduction. In the case of phosphatidylinositol, the head group can be enzymatically modified by the addition of one, two or three phosphate groups, this constituting another mechanism of cell signalling. While phospholipids are the major component of biological membranes, other non-glyceride lipid components like sphingolipids and sterols (such as cholesterol in animal cell membranes) are also found in biological membranes.

A biological membrane is a form of lipid bilayer, as is a liposome. The formation of lipid bilayers is an energetically-preferred process when the glycerophospholipids described above are in an aqueous environment. In an aqueous system, the polar heads of lipids orientate towards the polar, aqueous environment, while the hydrophobic tails minimise their contact with water. The lipophilic tails of lipids (U) tend to cluster together, forming a lipid bilayer (1) or a micelle (2). Other aggregations are also observed and form part of the polymorhism (biophysics) of amphiphile (lipid) behaviour. The polar heads (P) face the aqueous environment, curving away from the water. Phase behaviour is a complicated area within biophysics and is the subject of current academic research.

Micelles and bilayers form in the polar medium by a process known as the lipophilic effect. When dissolving a lipophilic or amphiphilic substance in a polar environment, the polar molecules (i.e. water in an aqueous solution) become more ordered around the dissolved lipophilic substance, since the polar molecules cannot form hydrogen bonds to the lipophilic areas of the amphiphile. So in an aqueous environment the water molecules form an ordered "clathrate" cage around the dissolved lipophilic molecule.

s. A lipid bilayer is shown on the left and a micelle on the right.

The self-organisation depends on the concentration of the lipid present in solution. Below the critical micelle concentration, the lipids form a single layer on the liquid surface and are (sparingly) dispersed in the solution. At the first critical micelle concentration (CMC-I), the lipids organise in spherical micelles, at given points above this concentration, other phases are observed (see lipid polymorphism).

Nutrition and health Lipids play diverse and important roles in nutrition and health. Many lipids are absolutely essential for life, however, there is also considerable awareness that abnormal levels of certain lipids, particularly cholesterol (in hypercholesterolemia) and, more recently, fatty acids with trans fatty acids, are risk factors for heart disease amongst others. We need fats in our bodies and certain types in our diet. Animals in general use fat for energy storage because fat stores 9 KCal/g of energy. Plants, which do not require energy for movement, can afford to store food for energy in a less compact but more easily accessible form, so they have evolved to use starch, a carbohydrate, (not a lipid) for energy storage. Carbohydrates and proteins store only 4 KCal/g of energy, so fat stores over twice as much energy/gram as other sources of energy. Furthermore, lipids can be stored in an anhydrous form whereas carbohydrates typically cannot, which means that anhydrous lipid stores about 6 times as much energy per weight as hydrated carbohydrates. As an example, a typical 70 kg man would have to weigh approximately 125 kg if his energy stores were converted from triacylglycerol to glycogen.

The baby formula brands Enfamil and Similac offer versions with lipids (Docosahexaenoic acid and Arachidonic acid) added to the base formula.

Types of Lipids







References

See also

External links

and cholesterol. In the middle is a triglyceride composed of oleate, stearate, and palmitate chains attached to a glycerol backbone. At the bottom is the common phospholipid phosphatidylcholine. Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including triglyceride, diglyceride, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing metabolites such as cholesterol.

Lipids have many functions in living organisms including nutrients, energy storage, structural components of cell membranes, and important lipid signaling. Although the term lipid is sometimes used as a synonym for fat, fats are in fact a subgroup of lipids called triglycerides and should not be confused with the term fatty acid.

Fatty acids and glycerides Chemically, fatty acids can be described as long-chain monocarboxylic acids the saturated examples of which have a general structure of CH3(CH2)nCOOH. The length of the chain usually ranges from 12 to 24, always with an even number of carbon atoms. When the carbon chain contains no double bonds, it is a saturated chain. If it contains one or more such bonds, it is unsaturated. The presence of double bonds reduces the melting point of fatty acids. Furthermore, unsaturated fatty acids can occur either in cis or trans geometric isomerism. In naturally occurring fatty acids, the double bonds are in the cis-configuration.

Glycerides are lipids possessing a glycerol (another name for which is propan-1, 2, 3-triol) core structure with one or more fatty acyl groups, which are fatty acid-derived chains attached to the glycerol backbone by ester linkages. Glycerides with three acyl groups (triglycerides or neutral fats) are the main form of fatty energy storage in animals and plants.

An important type of glyceride-based molecule found in biological membranes, such as the cell's plasma membrane and the intracellular membranes of organelles, are the phosphoglycerides or glycerophospholipids. These are phospholipids that contain a glycerol core linked to two fatty acid-derived "tails" by ester or, more rarely, ether linkages and to one "head" group by a phosphate ester linkage. The head groups of the phospholipids found in biological membranes are phosphatidylcholine (also known as PC, and lecithin), phosphatidylethanolamine (PE), phosphatidylserine and phosphatidylinositol (PI). These phospholipids are subject to a variety of functions in the cell: for instance, the lipophilic and polar ends can be released from particular phospholipids through enzyme-catalysed hydrolysis to generate secondary messengers involved in signal transduction. In the case of phosphatidylinositol, the head group can be enzymatically modified by the addition of one, two or three phosphate groups, this constituting another mechanism of cell signalling. While phospholipids are the major component of biological membranes, other non-glyceride lipid components like sphingolipids and sterols (such as cholesterol in animal cell membranes) are also found in biological membranes.

A biological membrane is a form of lipid bilayer, as is a liposome. The formation of lipid bilayers is an energetically-preferred process when the glycerophospholipids described above are in an aqueous environment. In an aqueous system, the polar heads of lipids orientate towards the polar, aqueous environment, while the hydrophobic tails minimise their contact with water. The lipophilic tails of lipids (U) tend to cluster together, forming a lipid bilayer (1) or a micelle (2). Other aggregations are also observed and form part of the polymorhism (biophysics) of amphiphile (lipid) behaviour. The polar heads (P) face the aqueous environment, curving away from the water. Phase behaviour is a complicated area within biophysics and is the subject of current academic research.

Micelles and bilayers form in the polar medium by a process known as the lipophilic effect. When dissolving a lipophilic or amphiphilic substance in a polar environment, the polar molecules (i.e. water in an aqueous solution) become more ordered around the dissolved lipophilic substance, since the polar molecules cannot form hydrogen bonds to the lipophilic areas of the amphiphile. So in an aqueous environment the water molecules form an ordered "clathrate" cage around the dissolved lipophilic molecule.

s. A lipid bilayer is shown on the left and a micelle on the right.

The self-organisation depends on the concentration of the lipid present in solution. Below the critical micelle concentration, the lipids form a single layer on the liquid surface and are (sparingly) dispersed in the solution. At the first critical micelle concentration (CMC-I), the lipids organise in spherical micelles, at given points above this concentration, other phases are observed (see lipid polymorphism).

Nutrition and health Lipids play diverse and important roles in nutrition and health. Many lipids are absolutely essential for life, however, there is also considerable awareness that abnormal levels of certain lipids, particularly cholesterol (in hypercholesterolemia) and, more recently, fatty acids with trans fatty acids, are risk factors for heart disease amongst others. We need fats in our bodies and certain types in our diet. Animals in general use fat for energy storage because fat stores 9 KCal/g of energy. Plants, which do not require energy for movement, can afford to store food for energy in a less compact but more easily accessible form, so they have evolved to use starch, a carbohydrate, (not a lipid) for energy storage. Carbohydrates and proteins store only 4 KCal/g of energy, so fat stores over twice as much energy/gram as other sources of energy. Furthermore, lipids can be stored in an anhydrous form whereas carbohydrates typically cannot, which means that anhydrous lipid stores about 6 times as much energy per weight as hydrated carbohydrates. As an example, a typical 70 kg man would have to weigh approximately 125 kg if his energy stores were converted from triacylglycerol to glycogen.

The baby formula brands Enfamil and Similac offer versions with lipids (Docosahexaenoic acid and Arachidonic acid) added to the base formula.

Types of Lipids







References

See also

External links



 

Lipid



 
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