{"id":230,"date":"2017-10-27T17:14:10","date_gmt":"2017-10-27T17:14:10","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/sunynutrition\/?post_type=chapter&p=230"},"modified":"2017-11-10T18:25:20","modified_gmt":"2017-11-10T18:25:20","slug":"2-36-phospholipids","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/atd-herkimer-nutrition\/chapter\/2-36-phospholipids\/","title":{"raw":"2.36 Phospholipids","rendered":"2.36 Phospholipids"},"content":{"raw":"
\r\n\r\nPhospholipids are similar in structure to triglycerides, with the only difference being a phosphate group and nitrogen-containing compound in the place of a fatty acid.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"290\"]\"\" Figure 2.361 Structure of a phospholipid, R represents the different fatty acids, X represents the nitrogen-containing compound off of the phosphate group1<\/sup>[\/caption]\r\n\r\n<\/div>\r\nThe best known phospholipid is phosphatidylcholine (aka lecithin). As you can see in the structure below, it contains a choline off of the phosphate group.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1034\"]\"\" Figure 2.362 Structure of phosphatidylcholine (lecithin)[\/caption]\r\n\r\n<\/div>\r\nHowever, you will not normally find phospholipids arranged like a triglyceride, with the 3 tails opposite of the glycerol head. This is because the phosphate\/nitrogen tail of the phospholipid is polar. Thus, the structure will look like the 2 figures below.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"530\"]\"\" Figure 2.363 Structure of phosphatidylcholine (lecithin)2<\/sup>[\/caption]\r\n\r\n<\/div>\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"598\"]\"\" Figure 2.364 Structure of phosphatidylcholine (lecithin)3<\/sup>[\/caption]\r\n\r\n<\/div>\r\nSimilar to triglycerides, phospholipids are also represented as a hydrophilic head with two hydrophobic tails as shown below.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1123\"]\"\" Figure 2.365 Schematic of a phospholipid[\/caption]\r\n\r\n<\/div>\r\nPhospholipid Functions<\/b>\r\n\r\nBecause its structure allows it to be at the interface of water-lipid environments, there are two main functions of phospholipids:\r\n\r\n1. Key Component of the Cell's Lipid Bilayer\r\n\r\n2. Emulsification\r\n\r\nNumber 1 in the figure below is a cell's lipid bilayer, while 2 is a micelle that is formed by phospholipids to assist in emulsification.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"530\"]\"\" Figure 2.366, 1 - lipid bilayer, 2 - micelle4<\/sup>[\/caption]\r\n\r\n<\/div>\r\n1. Key Component of Cells' Lipid Bilayers<\/b>\r\n\r\nPhospholipids are an important component of the lipid bilayers of cells. A cross section of a lipid bilayer is shown below. The hydrophilic heads are on the outside and inside of the cell; the hydrophobic tails are in the interior of the cell membrane.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"613\"]\"\" Figure 2.367 Phospholipids in a lipid bilayer. The blue represents the watery environment on both sides of the membrane, while the dark green represents the the hydrophobic environment in between the membranes5<\/sup>[\/caption]\r\n\r\n<\/div>\r\n2. Emulsification<\/b>\r\n\r\nAs emulsifiers, phospholipids help hydrophobic substances mix in a watery environment. It does this by forming a micelle as shown below. The hydrophobic substance is trapped on the interior of the micelle away from the aqueous environment.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"532\"]\"\" Figure 2.368 Structure of a micelle6<\/sup>[\/caption]\r\n\r\n<\/div>\r\nAs a result, it can take a hydrophobic liquid (oil) and allow it to mix with hydrophilic liquid (water).\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"180\"]\"\" Figure 2.369 How an emulsion can allow the dispersion of a hydrophobic substance (II) into a hydrophilic environment (I) as shown in D7<\/sup>[\/caption]\r\n\r\n<\/div>\r\nFoods rich in phosphatidylcholine include: egg yolks, liver, soybeans, wheat germ, and peanuts8<\/sup>. Egg yolks serve as an emulsifier in a variety of recipes. Your body makes all the phospholipids that it needs, so they do not need to be consumed (not essential).\r\n\r\nReferences & Links<\/b>\r\n\r\n1. http:\/\/en.wikipedia.org\/wiki\/File:Phospholipid.svg\r\n\r\n2. http:\/\/commons.wikimedia.org\/wiki\/File:Popc_details.svg\r\n\r\n3. http:\/\/en.wikipedia.org\/wiki\/File:Phosphatidylcholine.png\r\n\r\n4. http:\/\/en.wikipedia.org\/wiki\/File:Lipid_bilayer_and_micelle.png\r\n\r\n5. http:\/\/en.wikipedia.org\/wiki\/File:Bilayer_hydration_profile.svg\r\n\r\n6. https:\/\/en.wikipedia.org\/wiki\/Micelle#\/media\/File:Micelle_scheme-en.svg\r\n\r\n7. http:\/\/en.wikipedia.org\/wiki\/File:Emulsions.svg\r\n\r\n8. Byrd-Bredbenner C, Moe G, Beshgetoor D, Berning J. (2009) Wardlaw's perspectives in nutrition. New York, NY: McGraw-Hill.\r\n\r\n<\/div>","rendered":"
\n

Phospholipids are similar in structure to triglycerides, with the only difference being a phosphate group and nitrogen-containing compound in the place of a fatty acid.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.361 Structure of a phospholipid, R represents the different fatty acids, X represents the nitrogen-containing compound off of the phosphate group1<\/sup><\/p>\n<\/div>\n<\/div>\n

The best known phospholipid is phosphatidylcholine (aka lecithin). As you can see in the structure below, it contains a choline off of the phosphate group.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.362 Structure of phosphatidylcholine (lecithin)<\/p>\n<\/div>\n<\/div>\n

However, you will not normally find phospholipids arranged like a triglyceride, with the 3 tails opposite of the glycerol head. This is because the phosphate\/nitrogen tail of the phospholipid is polar. Thus, the structure will look like the 2 figures below.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.363 Structure of phosphatidylcholine (lecithin)2<\/sup><\/p>\n<\/div>\n<\/div>\n

\n
\"\"<\/p>\n

Figure 2.364 Structure of phosphatidylcholine (lecithin)3<\/sup><\/p>\n<\/div>\n<\/div>\n

Similar to triglycerides, phospholipids are also represented as a hydrophilic head with two hydrophobic tails as shown below.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.365 Schematic of a phospholipid<\/p>\n<\/div>\n<\/div>\n

Phospholipid Functions<\/b><\/p>\n

Because its structure allows it to be at the interface of water-lipid environments, there are two main functions of phospholipids:<\/p>\n

1. Key Component of the Cell’s Lipid Bilayer<\/p>\n

2. Emulsification<\/p>\n

Number 1 in the figure below is a cell’s lipid bilayer, while 2 is a micelle that is formed by phospholipids to assist in emulsification.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.366, 1 – lipid bilayer, 2 – micelle4<\/sup><\/p>\n<\/div>\n<\/div>\n

1. Key Component of Cells’ Lipid Bilayers<\/b><\/p>\n

Phospholipids are an important component of the lipid bilayers of cells. A cross section of a lipid bilayer is shown below. The hydrophilic heads are on the outside and inside of the cell; the hydrophobic tails are in the interior of the cell membrane.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.367 Phospholipids in a lipid bilayer. The blue represents the watery environment on both sides of the membrane, while the dark green represents the the hydrophobic environment in between the membranes5<\/sup><\/p>\n<\/div>\n<\/div>\n

2. Emulsification<\/b><\/p>\n

As emulsifiers, phospholipids help hydrophobic substances mix in a watery environment. It does this by forming a micelle as shown below. The hydrophobic substance is trapped on the interior of the micelle away from the aqueous environment.<\/p>\n

\n
\"\"<\/p>\n

Figure 2.368 Structure of a micelle6<\/sup><\/p>\n<\/div>\n<\/div>\n

As a result, it can take a hydrophobic liquid (oil) and allow it to mix with hydrophilic liquid (water).<\/p>\n

\n
\"\"<\/p>\n

Figure 2.369 How an emulsion can allow the dispersion of a hydrophobic substance (II) into a hydrophilic environment (I) as shown in D7<\/sup><\/p>\n<\/div>\n<\/div>\n

Foods rich in phosphatidylcholine include: egg yolks, liver, soybeans, wheat germ, and peanuts8<\/sup>. Egg yolks serve as an emulsifier in a variety of recipes. Your body makes all the phospholipids that it needs, so they do not need to be consumed (not essential).<\/p>\n

References & Links<\/b><\/p>\n

1. http:\/\/en.wikipedia.org\/wiki\/File:Phospholipid.svg<\/p>\n

2. http:\/\/commons.wikimedia.org\/wiki\/File:Popc_details.svg<\/p>\n

3. http:\/\/en.wikipedia.org\/wiki\/File:Phosphatidylcholine.png<\/p>\n

4. http:\/\/en.wikipedia.org\/wiki\/File:Lipid_bilayer_and_micelle.png<\/p>\n

5. http:\/\/en.wikipedia.org\/wiki\/File:Bilayer_hydration_profile.svg<\/p>\n

6. https:\/\/en.wikipedia.org\/wiki\/Micelle#\/media\/File:Micelle_scheme-en.svg<\/p>\n

7. http:\/\/en.wikipedia.org\/wiki\/File:Emulsions.svg<\/p>\n

8. Byrd-Bredbenner C, Moe G, Beshgetoor D, Berning J. (2009) Wardlaw’s perspectives in nutrition. New York, NY: McGraw-Hill.<\/p>\n<\/div>\n\n\t\t\t

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Candela Citations<\/h3>\n\t\t\t\t\t
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