9-11-06, Carbohydrates and Lipids There are 4 major organic molecules. They are built from carbon atoms put into chains. These chains build monomers. Last week we talked about the 4 types of monomers per organic molecule. The first was amino acids for proteins, we mentioned nucleo-tides (nucleic acids), we went in depth into proteins, and now we will cover the monomers for carbohydrates and the monomers for lipids. First of all, glucose is considered to be the monomer for carbohydrates. Glucose normally forms a geometrical figure (molecular structure) that basically has 6 points. There are carbon atoms at each one of those 6 points. We refer to each of those 6 connecting carbon atoms as prime points (this will become very important to us later on). <image here> Generally speaking, prime 1 is at the far right-hand point of the geometrical figure. Then it will go clockwise for prime 2, prime 3, 4, 5, 6, and so on. Five and 6 are on the top of the figure (the carbon atoms). Now, we also know that, although glucose is considered to be the monomer, there are several sugars that have the same chemical formula and each of these are isomers (of glucose). Galactose is one of these. Dextrose is one of those isomers as well. Condensation reaction is where water is proposed. This is also called dehydration synthesis. Polymers are formed from monomers through dehydration synthesis which is also called condensation reaction. We are going to make this simple. Chemical equation … Mono + Mono -> polymer + water. When we add a mono to a mono we get a polymer and, and what? And water. The reverse action where we break down polymers to monomers requires waters. Individual monomeric units can be made through hydrolysis to break down a polymer. Hydrolysis is where we add water and some polymer and then we get multiple molecules of monomers, man that’s hard to say. Each of the covalent bonds by the addition of water to the reaction, and again, this process is called hydrolysis. If you again, take a look at the geometric figure. Because there are 6 carbon atoms in that glucose, that multiples the connecting points for those covalent bonds immensely. If we add one more geometric figure, and we just connect it here on the lower-right hand corner of glucose (that diagram above) then we have multiplied it by 2, basically. For each carbon bond in carbohydrates, there is a usable amount of energy that is stored in the bonds. Let’s go back to carbon bonds. In each one of the bonds between the carbon bonds there is an enormous amount of cellular energy stored there. The formation of carbohydrates is endergonic reactions (store energy). Exergonic reactions release energy. When carbon atoms in this style come together they form energy-storing bonds. The larger the molecules the more energy is there. When we talk about complex carbohydrates we are talking about gigantic macromolecules that store an enormous amount of cellular energy. Carbohydrates exist in 4 different forms. The more basic of carbohydrates are what we refer to as simple sugars which are called monosaccharides. Monosaccharides are generally isomers of glucose. Monosacchardies build into the second level of carbohydrates which are disaccharides. In order to be a carbohydrate, what are two characteristics? What are two basic characteristics of carbohydrates? Here’s the first one. All carbohydrates, and when I say it, you’re going to say ―oh yeah‖, all carbohydrates have a hydrogen-to-oxygen ratio that is the same as water (2 to 1). There is the hydrogen-oxygen ratio that is the same as water. In all condensation reactions where we take an individual monomer and we put them with two other monomer the hydrogen-oxygen ratio stays the same regardless of how big the carbohydrate is. The second characteristic is that carbohydrates produce geometric molecular structures, kind of like honeycombs. Generally speaking, monosacchardies and disaccharides end in the suffix ―-ose‖. Galactose. Fructose. Et cetera-ose. The third level of carbohydrates is when we continue to add dissachhirdes through condensation reactions combined with other disacchirdes and at this particular point we are going to call them polysaccharides. Of course, polysaccharides are what we commonly know as complex carbohydrates. Polysaccharides are going to exist in nature in 1 of 3 forms. Cellular chemical pathways are designed to either break down or form polysaccharides, these cellular metabolic pathways build these sorts of carbohydrates (especially in plants). The end result of this carbohydrate building is going to be 1 of 3 types of polysaccharides The first of which is cellulose. Cellulose is a complex structural carbohydrate found in plant cells, it makes cell walls (in plants). An interesting thing about cellulose is that most animals do not have an enzyme pathway that breaks down cellulose – this means that cellulose passes through an animal in its complex form and we call this roughage. These large amounts of cellulose that pass through the digestive tracts. What digests cellulose? Bacteria digest bacteria. When cows eat plants (the majority of herbivores) the material is going to go into their first of four stomachs and that plant material is going to be broken down with some strong acids, and then that food goes into another stomach, and then they bring up that material and they chew it again, which breaks it down to a basic cellular form, and then that third stomach contains a celluloitic bacteria that breaks it down into its individual monomers and then the fourth stomach continues the digestive process. The herbivores transfer cellulose energy into a usable form for carnivores. The only way that we can get that cellular energy from cellulose is for herbivores to break it down (well, the bacteria breaks it down). The second form of a complex carbohydrate (polysaccharide) is a starch. The first was cellulose. There is a basic chemical equation that you should be introduced to. This is a hydrolysis reaction that produces C6H12O6 and O2. It starts with CO2 and H2O. This is photosynthesis. This is the basic process that is photosynthesis. The function of photosynthesis is not to make energy. The function of photosynthesis is to take the carbon atom from carbon dioxide and then insert it into a series of 5 carbon atoms and eventually produce glucose. We are non-photosynthetic organisms so we have to have a process which gets that energy that is necessary to lock that carbon atom into glucose. We rapidly use up too much glucose. Glucose is a quick energy burst for us, and we need a long-term source of glucose, and this long-term source is found in plants and photosynthesis. Those photosynthetic processes lock those carbon atoms into starch. We could not live without some intake of starch – potatoes, white-bread, pasta—these are all high-starch, though low-starch includes tomatoes and cucumbers. The better diets have you on low- starch foods. Starch is how complex carbohydrates are transferred from plant matter to animal matter. The third level of polysacchirdes is ―what happens to starch in an animal cell?‖. Well, that starch is re-organized into a substance called glycogen. And, as Jessica mentioned, cellular respiration in animal cells does not occur without glycogen first forming. Glycogen is the first step in the process that eventually removes the energy from those carbon bonds in glucose. Glycogen is animal’s carbohydrate. Glycogen is reorganized in the human body into glucogen, and it’s reduced to a simpler carbohydrate, and then sent into the human blood-stream. Insulin is produced by the pancreas, and it begins a chain of reaction that causes glucogen to break down into individual glucose molecules and it tells cells to begin absorbing glucogen. Helical structures are identifying structures. Insulin tells ―antennas‖ to take notice to take some glucogen and take care of it. Adrenalin causes insulin-rushes because that’s where you get your burst of energy. Diabetics can no longer produce insulin and so therefore if they have no insulin in their bloodstream and then their sugar content becomes high (no cells are absorbing the sugars (glycogen) in the bloodstream). The high sugar levels in the bloodstream isn’t fixed. So, cells start to shut down and go into a diabetic comma, because there’s no sugar available to them (no insulin triggering cells to take the glycogen). If you take artificial insulin, then you cause all of the sugar to be used up, and then there’s quickly a reverse action and we call that an insulin shock, because there are ways of measuring blood-sugar content all day long. If you use up too much sugar then you don’t have enough sugar to go on. This is why diabetics are told to carry around hard candy so that the insulin has something to work on. It’s a fine line between too much and not enough. Carbohydrates are the basic energy monomer starting with glucose, building into two monomeric units called disaccharides, building into multiple units called polysaccharides. Three types of polysaccharides include cellulose, starch, and glycogen. The function of carbohydrates is to provide the energy necessary for cellular metabolism. The third organic molecule that we want to talk about is going to be those groups of molecules that we call lipids. The basic criteria of something being a lipid is first and foremost that they are long carbon chains with hydrogen-wings connected to each of the carbon atoms. For each of the carbon atoms there are 2 hydrogen atoms. Although they are not technically monomers, many lipids are formed from two or more molecules linking together we just lump them together as monomers. There are 4 basic kinds of lipids. The first of those 4 kinds are called fats. Fats are formed from long chains of fatty acid molecules. Generally, they will have a carbonyl head and a carboxyl tail. This goes back to functional groups that we talked about. Fatty acids are almost always water repellent because of the long hydrogen backbone of the molecule. Generally speaking, fatty acids will form 3 different chains off of the carbonyl head which causes them to be triglycerides. If we add a hydroxyl group to those then the second types of those is a glycerol molecule. Glycerol is a triglyceride that made it (it has a hydroxyl group attached to it). The third type of lipid is the ones that we are familiar with when studying cell membranes, phospholipids, which have a phosphate group attached (another one of those functional groups). These will have 2 chains instead of 3. The fourth type of lipid is called a steroid. In your study for your free-response, you will find that steroids are lipids only because they are insoluble in water (like all other lipids). Steroids are geometrical (generally with 5 carbons as opposed to the 6 carbons of carbohydrates). There are types of steroids. You will continue to research steroids tomorrow. The types of steroids are determined by the attachment points of the functional groups. We are going to start with a 5-sided figure. It looks like a house. The points of attachment with functional groups determine what type of steroid it is. The basic type of steroid is cholesterol. Today we want to focus on the fact that cholesterol is a steroid. All other steroids are generated with cholesterol as the base molecule. Cholesterol exists in the bloodstream, but it’s not a long chain of carbon atoms, but it’s not really a fat. It’s insoluble in water. Cholesterol cause reactions to occur differently, they are a sort of chemical control. Cholesterol causes a build up in your arteries. Cholesterol connects because it has such a nice pretty geometrical shape (geometrical shapes fit together). It’s really not a fat. Cholesterol is the foundation. One of the major functions of cholesterol is that it’s a primary component of the cell membrane that functions in cell-to-cell communication. It is interspersed within the phospholipids within the cell membranes (not necessarily interacting with the phospholipids). Lipids provide long-term energy storage. All of those carbon-bonds are hooked-together with usable cellular energy. When we think about the fats, and that’s what we’re thinking about here, phospholipids are those cell membranes things, but really we’re talking about the ―true fats‖. These are gigantic molecules with lots of energy locked in there. There are 2 kinds of fats. The first is saturated fat. There are also unsaturated fats. Saturated fats are normally animal fats and normally solids at room temperature. Saturated fats are formed from single carbon bonds. Of the two types, saturated fats are less good for you – though note that I did not say ―bad for you‖. Anything that you do in moderation is probably okay, so always do things in moderation. There are things in exceptions – like drugs, those are never good for you. Unsaturated fats are plant fats formed from double carbon bonds. We refer to them as oils because they are liquid at room temperature and they are the better of the two. In particular, for some reason, olive oil. There is one other of the groups of molecules that should be touched upon. These are called water. There are some very simple forms of water. There is a reason for this. There is a very special nature of water that has some enormous life supporting qualities that the other molecules don’t have. The following is a collection of notes added after the lecture. There seems to be a pattern in that the carbohydrates can combine in very specific manners. There seems to be some geometrical structural tendencies of glucose to bond to another glucose molecule at two of the carbon primes. This suggests that there are different patterns in the geometrically bonded glucose molecules that form the polysaccharides (still carbohydrates).
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