Carbohydrates and Lipids

Carbohydrates

Carbohydrates

Monosaccharides

There are different kinds of carbohydrates and each of them comes along with the suffix or ending saccharide.  Monosaccharides are simple sugars.  Your body thinks of these like cash in the bank.  Ready to spend, it’s right in your pocket you can really get energyThe capacity to do work or cause change. very simply out of it.  We have things like glucoseA simple sugar that is the main source of energy for cells. fructose galactose.  These are all the things you crave so much because they are tasty.  Cookies, Starbucks, and just goodness.

Disaccharides

When we combine two monosaccharides we get a disaccharide, which is just two monosaccharides bonded together.  Lactose is a great example.  We’ve got glucose and galactose bonded together.  Sucrose or table sugar is another example.

Lactose intolerant people can’t digest or break this bond between the monosaccharides.  They lack the enzyme lactase that digests lactoseA disaccharide sugar found in milk. and the complete molecule passes through the digestive tract…painfully. 

Polysaccharides are just big

Polysaccharides are known as our complex carbs in our diet.   We know the dietary complex carbs like starches but there is the lesser known glycogen A stored form of glucose in muscles and the liver. which is found in animal muscle.  Common to all of them is that they are made up of a very large amount of monosaccharide subunits.

Cellulose

I love celery I like to grow in my garden.  I grow Utah celery.  When it’s nice and fresh it has this nutty flavor.  Those strings are made of cellulose.  Made only by plants, it’s indigestible by animals.  Similar to those who are lactose intolerant from a lack of the lactase enzyme, we all lack the digestive enzymesProteins that speed up chemical reactions in the body. to digest cellulose. Things that contain cellulose like celery add dietary fiber to your diet.

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 energy 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..

Triglycerides

In our diets, lipids are more like having a check from someone.  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.  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 .

Types of fatty acids

The three fatty acidA substance that releases hydrogen ions (H⁺) in solution. tails can have different structures from each other.  This is where we get the terminology saturated unsaturated polyunsaturated you can discuss this in detail in one of the nutrition classes that we offer here at FCC but for here in biology we can discuss very quickly some of the types of fatty acids.

This fatty acid up at the top is saturated with hydrogen atomsThe smallest units of matter that retain the properties of an element..  The carbons are holding as many of them as they can. 

Let’s compare the mono unsaturated to the saturated.  The mono unsaturated has one area where the hydrogen bondsWeak attractions between hydrogen and electronegative atoms like oxygen or nitrogen. have been broken.  The bond has been replaced with a bond between 2 carbons giving a double bond between the carbons.   You can see it just progresses with polyunsaturated, adding more double bonds between the carbons.

We’ve accumulated more of those double bonds.   Partially hydrogenated fats which are like margarine.   The polyunsaturated fats have hydrogens forced back on it to make it saturated. 

Trans fats which basically forms like a kink in the structure between carbons.

Unsaturated fats things that are liquid at room temperature like olive oils and peanut oil.  These fats breakdown very easily room temperature, and go rancid very easily.   This means that they also can break down very easily in your body providing it easy source of energy.

When we have things like saturated fats like butter and ice cream our body doesn’t break them down.  That’s why some of them they have a very long shelf life.  There are some things called butter bells or butter bowls where you put the butter in this container and then invert it into a small film of waterThe universal solvent essential for life. thus preventing any oxygen or light from getting into it and making the bonds rancid.

Fats

Before we get started here I just want to tell you that I did not create this I actually stole the idea from Alton Brown who has some really great cookbooks that build on the science of molecules. He talks about your kitchen and your pantry and the ways that you cook and how you’re manipulating all of these biological molecules.

We can think of the carbon chain of a fatty acid as these ladies.   They are bonded together and each of them is holding their nice little shopping bags or the hydrogen atoms.  This is a saturated fat. If we take away some of the hydrogen atoms forming double bonds between the ladies then we have an unsaturated fat.   Unfortunately unsaturated fats go rancid.  If we force hydrogen atoms onto it, breaking the double bonds between the ladies, we can make a partially hydrogenated fat.  The simple rule here though is if a fat has a long shelf life it’s gonna stay in your body for a longer period of time .

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. 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 .

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. 

Phospholipids form a bilayer

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 of this little bubble.  They also exposed to the water inside of the 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.