Biological Molecules: 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 or calories per weight.  If you’re consuming lots of lipids, that might not be good for you as a human, depending on the types of lipids you are consuming, but 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 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..

Fats and Oils

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 and then you withdraw the cash (energy) at a later point 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 or they can be unsaturation where 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 and the bag of fat goes over the barbed wire at it starts spilling all over the place.  I know that movie’s old but I’m old and that was a great movie .

Trans Fats

Trans fats are a type of unsaturated fat that has been chemically altered in a process called hydrogenation. Normally, unsaturated fats have a “kink” or bend in their structure (because of double bonds between carbon atomsThe smallest units of matter that retain the properties of an element.). This bend allows the fat molecules to remain liquid at room temperature. However, during hydrogenation, some of these bent molecules are changed so that they have a straight shape, which makes them behave more like saturated fats (solid fats) at room temperature.

So, trans fats are created by changing the chemical structure of unsaturated fats in a way that makes them more solid, even at room temperature. This change in structure is what makes trans fats unhealthy and different from other types of fats.

A common example of food containing trans fats is margarine or shortening. These are often used in processed foods like baked goods (cookies, cakes, pies), french fries, and snack foods (like chips). These foods might have a label saying “partially hydrogenated oils,” which means they contain trans fats.

For example, imagine you’re eating a store-bought pie. The crust might be made with hydrogenated vegetable oil (which contains trans fats), making the pie crust crispy and flaky. The hydrogenation process helps the oil stay solid and maintain its texture, but it also creates trans fats, which can have negative effects on your health.

Trans fats are used in many processed foods because they are cheap, help extend the shelf life of foods, and create a desirable texture (like making things crispy or flaky). However, over time, as we’ve learned more about their harmful effects, many food manufacturers have started to remove trans fats from their products or reduce their use.

Omega Fatty Acids

Omega-3 fatty acids are a type of polyunsaturated fat that are essential for human health because the body cannot produce them, so they must be obtained through diet. The name “omega-3” comes from the position of the first double bond in their carbon chain, which is located three carbons away from the methyl (omega) end of the molecule.

Omega-3s are known to reduce inflammation, lower triglycerides and raise heart health, and contribute to brain developmentThe process of growth and differentiation..  You see DHA omega-3 advertised on many child supplement drinks.

Of course, eating foods naturally high in omega-3s provides these benefits.  You have to want to eat things like salmon, mackerel, and sardines.  Hey, I like to eat fish, but not those.  Thank goodness that they are also found in flaxseeds, chia seeds, and walnuts.

Waxes

A wax is a type of lipid that is composed of long-chain fatty acids esterified to long-chain alcohols. Waxes are hydrophobic, making them water-repellent, and they are typically solid at room temperature due to their long hydrocarbon chains.  Many plants have a waxy layer on their leaves and stems, known as the cuticle, which prevents waterThe universal solvent essential for life. loss and protects against environmental damage.  Bees produce beeswax to build honeycombs, while whales produce spermaceti, a wax found in their heads.   Waxes are used in candles, polishes, cosmetics (e.g., lip balms), and waterproofing products.

Biologically, waxes serve as barriers and insulators, helping organisms retain moisture and protect against harsh conditions. Their chemical stability and hydrophobic nature make them valuable both in nature and in human applications.

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 water 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.   Somewhat like a sandwich:  the polar heads are the bread and the nonpolar region is whatever it is you want inside of your sandwich… hummus, fluff whatever you like.

Steroids

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. released from your adrenal glandPaired endocrine glands above the kidneys producing stress-related hormones. and mineralocorticoidsRegulate electrolyte and water balance (e.g., aldosterone). like aldosteroneA hormone that increases sodium and water reabsorption in the kidneys, helping regulate blood pressu which monitors the sodium(Na⁺): Major ECF cation; important for fluid balance, nerve function. balance in your potassium(K⁺): Major ICF cation; essential for muscle and nerve function. balance by influencing your kidney .