Lipids

Lipids

Moving on to the next category of biological moleculesGroups of atoms bonded together. remembering that there were carbs lipidsOrganic molecules including fats, oils, and steroids. proteinsLarge molecules made of amino acids with various functions in the body. and nucleic acids.  Lipids unlike carbohydrates, are hydrophobic.   If you have taken a nutrition class, you know that lipids have the most energyThe capacity to do work or cause change. per gram. They have the highest calories per weight.  Consuming lots of lipids might not be good for you as a human. It depends on the types of lipids you are consuming. However, a fat little bird like this stores up on lipids before he flies South for the summer.  Since lipids contain the most energy per weight, this fat little bird prefers to stock up on them. This is crucial for this intensely demanding migration south.  For us as humans, lipids are necessary in our diet.   They do some really important things like energy storage, but they also do insulation and cushioning.  We all know about baby fat, especially on the posterior area.  Simply, this fat provides cushioning when we fall while learning to walk..

Triglycerides

In our diets, lipids are more like having a check from someone rather than the cash of carbohydrates.  You deposit it in the bank of fat deposits. Later, you withdraw the cash (energy) to buy some ATPThe energy currency of cells used for muscle contraction.. 

Triglycerides are named because they have 3 fatty acids and a glycerol headRounded proximal end that fits into the acetabulum of the hip bone..   These are the major dietary currency.  Those three fatty acidA substance that releases hydrogen ions (H⁺) in solution. tails there can be saturated with tons of hydrogen. Alternatively, they can have unsaturation, meaning some hydrogens have been removed.  Whenever I talk about triglycerides, I can’t help but think of the movie Fight Club.  They are stealing fat from a plastic surgery center to make explosives. The bag of fat goes over the barbed wire and starts spilling all over the place.  I know that movie’s old but I’m old and that was a great movie .

Sterols

Moving on from triglycerides we have a second kind of lipid which is a sterol.  Sterols are made from cholesterolA lipid molecule that is a key component of cell membranes and a precursor for bile acids and steroi.   Cholesterol is necessary in your diet to form any of the steroid hormones like testosterone and estrogen.  Other steroid hormones of note are the glucocorticoidsSteroid hormones regulating metabolism and immune response. like cortisolA glucocorticoid involved in stress response, metabolism, and immune regulation.. These are released from your adrenal glandPaired endocrine glands above the kidneys producing stress-related hormones.. Mineralocorticoids like aldosteroneA hormone that increases sodium and water reabsorption in the kidneys, helping regulate blood pressu monitor the sodium(Na⁺): Major ECF cation; important for fluid balance, nerve function. balance in your body. They influence your kidney to maintain potassium(K⁺): Major ICF cation; essential for muscle and nerve function. balance.

Phospholipids

Our third and final category of lipids is phospholipids.   These are very important for us here in this class because they form the basicA solution with a pH above 7, having a lower concentration of H⁺ ions. structure of a cell membrane.   They look like a balloon with 2 strings on it.  They have this polar head and 2 nonpolar fatty acid tails coming off. Cell membranes are composed of a phospholipid bilayer or a double layer of phospholipids arranged very specifically.  In factA statement based on direct observation that is repeatedly confirmed., if you put phospholipids in waterThe universal solvent essential for life. and shake them up, they can form these little bubbles.  It might take a long time…like a millennia. The polar heads are exposed to the water outside AND inside of this little bubble.  The nonpolar tails are facing each other.   This forms a bilayer with a nonpolar region in the center.   This is somewhat like a sandwich. The polar heads are the bread. The nonpolar region is whatever you want inside your sandwich, like hummus or fluff.