Hey there folks!! Rakeeru here and it’s finally my turn again to share some thoughts on this blog. This week was pretty much wacky because there was so much to do and so little time to do it. I kid, I kid! I ‘m a master procrastinator but nothing can stop me from sharing some cool stuff about lipids. My love for lipids will never die… lol. My mission is to help you understand lipids in a fun and enjoyable way. So we are going to be looking at three types of structural membranes of lipids, phosphodiate, Sphingosine and cholesterol.
Let’s talk GLYCEROLPHOSPHOLIPIDS! So you guys should be familiar with the structure of glycerol, but if you aren’t, then let’s recap a bit. Glycerol is an alcohol that has three carbon atoms, each bonded to an alcohol group. Okay let’s go back to the glycerol phospholipids now. A Glycerol phospholipid, also known as a phosphodiate, has a glycerol as his backbone, where on carbon 1 only a saturated fatty acid chain is attached. On carbon 2 an unsaturated fatty acid chain is bonded and last but not least on carbon 3 a phosphate group is directly bonded to it. Note that when an alcohol is attached to an acid group it forms an ester bond. Look at the lovely diagram below.
Now this entire molecule is said to be amphipathic, meaning it has a polar end and a non-polar end. (See picture below). The polar end is hydrophilic or “water loving” while the non-polar end is hydrophobic or “water hating”. The polar end is the made up of a phosphate group and a hydroxyl group.
(R1 and R2 represent the fatty acid chain , the X represents the hydroxyl group) So Trav told you about the ability of unsaturated fatty acids to form a kink, and I just want to add a few things to that… Not all unsaturated fatty acids show a kink (changes direction of the chain). Unsaturated fatty acids can either be in cis configuration or trans configuration. ONLY CIS fatty acid chains display that appearance due to the fact that the C-3 and C-6 are on the same side of the double bond. (see the diagram below). In a trans fatty acid chain, the structure does not show any kinks. Instead, it follows the pattern of the fatty acid. It resembles the saturated fatty acid so I call it “the sly one”, since I cannot tell which one is the unsaturated fat and which in the saturated. O Boy, knowing that all the good-tasting stuff (junk food) is high in trans-fat which is terrible for health is a little scary, since the transfatty acid is packed tightly which increases the LDL( Low Density lipoprotein) and decreases HDL (High Density lipoprotein).
Okay moving on.. moving on… Another amazing lipid is… SPHINGOLIPID!!! 😀 This structure has a sphingosine backbone; sphingosine is an alcohol that has 18 CARBONS. There are many different functional groups attached to it. On carbon 1 and 3 there are hydroxyl groups present, an amino group attached to carbon 2 and a trans double bond is present in the middle of carbon 4 and 5. (See drawing below)
Remember I mentioned sphingosine is the backbone of the sphingolipid. What makes it a sphingolipid? It’s the presence of a saturated fatty acid chain. This fatty acid attaches to the carbon 2 that is bonded to an amino group to form an amide bond.
On carbon 1, there is an R group; this is simply any other group that is attached to the carbon, for example if hydrogen is R group then the name of the entire structure is ceramide. Ceramide is an oily substance that is found on the outer layer of the skin. It basically adds moisture to skin, which helps to prevent skin from drying and flaking. (Curel, 2014). Another example is sphingo myelin, which is created when the R group is phospocholine. The sphingo myelin is found in red blood cells and myelin sheaths. What captured my attention is that sphingo myelin increases the speed at which nervous impulses conduct themselves by insulating the nerve fibers. (Voet, Voet and Pratt, 2008). Pretty kool stuff. 😀 Last but not the least, Cholesterol!!! I’m sure you heard of this word before. But what exactly is cholesterol? Well here goes, cholesterol is a molecule that has 27 carbons. This molecule has 3 rings that have 6 carbon atoms and 1 ring that only has 5. These rings are referred to as steroids and are stuck together. Looking at ring B there is a double bond between carbon 5 and 6. There is a hydroxyl group on the carbon 3 atom and there is an alkyl group on the carbon 17. There are 2 methyl groups, one on carbon 19 and the other on carbon 18. By the way, in case you forgot what an alkyl group is, it’s a fragment of a molecule that has a general formula (CnH2n+1,). (Senese, 2010).
Well what’s so important about cholesterol? Believe it or not, without cholesterol we wouldn’t even exist. You know what’s amazing? The body is able to produce cholesterol on its own without consumption of food rich in cholesterol. (Mason W. Freeman, 2014). It plays an important role in the body:
- it forms bile acids to make digestion a lot easier in the intestine,
- Having cholesterol allows the body to produce vitamin D or hormones like testosterone. Testosterone is a steroid hormone that is produced in large amounts in males. It is responsible for the defining characteristics in men, and also for overall health and wellbeing.
- Cholesterol, together with phospholipids, makes up the membrane of cells in animals. Each cholesterol molecule attaches itself to a phospholipid group. The hydrophilic end of the cholesterol (where the hydroxyl group is located) is close to the hydrophilic end of the phospholipid. The hydrophobic portion of the cholesterol interacts with the hydrophobic portion of the phospholipid.
Just to spice things up a bit, have you ever wondered how cholesterol affects the fluidity of the membrane? Well it all depends on the temperature. In high temperature the cholesterol controls the movement of the phospholipid and lessens the fluidity. Heat energy encourages the phospholipids to move a lot which will destabilize the membrane. In low temperature the cholesterol controls the phospholipid by avoiding compaction. In cold conditions the phospholipid moves less and will become rigid.
Well that’s it for now! I hope my reflection was very informative and you guys learnt from this… Biochemistry is fun! BEST OF LUCK IN YOUR STUDIES!!! 😦 Unfortunately this is my last reflection… but my best buddy Shiv Shiv will do a tremendous job! Next up is nucleotides.. soo stay tuned… Until next time Rakeeru out!
- Curel. 2014. <https://www.curel.com/experts-corner/ceramides.aspx>.
- Mason W. Freeman, M.D. with Christine Junge. Harvard University . 2000-2014. <http://www.health.harvard.edu/newsweek/Understanding_Cholesterol.htm>.
- Senese, Fred. General Chemistry online. 1997-2010. <http://antoine.frostburg.edu/chem/senese/101/organic/faq/yl-ending.shtml>.
- Voet, Donald J., Judith G. Voet and Charlotte W. Pratt. ” Bilayers and Membranes.” Principles of Biochemistry third edition. 2008. 252.
- Polar and non-polar of phospholipid-http://upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Phospholipid.svg/290px-Phospholipid.svg.png
- cis and trans fatty acids-http://www.mansfield.ohio-state.edu/~sabedon/047cis.gif
- sphingosine- https://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/images/sphing.gif
- sphingosine fatty acid-http://upload.wikimedia.org/wikipedia/commons/a/a7/Sphingolipid.png
- Procrastination- http://www.quickmeme.com/img/95/95b5d62601a8d7a4b79ff15c5da165827719f3defa11fd02b5be11b6d6534de3.jpg
- Paula and Butter- https://i.chzbgr.com/maxW500/5591723264/h02E9A76E/
- Lipids are good- http://memecrunch.com/meme/2BR64/lipids/image.png
- Fluidity of membrane- http://web.sls.hw.ac.uk/teaching/Derek_J/A13MM1-web/files/revision_stuff/membranes/files/3_12.jpg