Chemistry Unit 7 Lesson 4

Cholesterol is a steroid.

Another class of lipids is the steroids. Cholesterol is an example of a steroid. It has a four-ringed structure with a hydroxyl group at one end and a short carbon chain at the opposite end. Cholesterol is also found in cell membranes and circulates in the blood. High levels of blood cholesterol levels can put a person at risk for heart and blood-vessel diseases. Cholesterol is made in the liver; it is also the base from which various steroid hormones are made. The male hormone testosterone and the female hormone estrogen have structures similar to cholesterol with different functional groups. The adrenal hormone cortisol is also made from cholesterol.

Waxes are also lipids.

Another type of lipid is wax. Wax is formed when a long-chain alcohol binds to a long-chain fatty acid. The hydroxyl group of the alcohol reacts with the carboxyl group of the fatty acid in a condensation reaction to form a covalent bond between the alcohol and the fatty acid. For example, the main ingredient in beeswax is triacontanylpalmitate, which is formed when an alcohol, triacontanol, binds to the fatty acid palmitic acid. Like fats, waxes are solids at room temperature. Other natural waxes are produced by plants and coat the surface of leaves and fruits. For example, the shiny coating of an apple is actually a thin coating of wax produced by the apple tree. *Waxes are among the longest-chain fats.

Carbohydrates and fats are important biochemicals.

Biochemistry is the study of the chemicals that are important to living things. It includes the structures and properties of biological compounds and the chemical reactions involved in making them and breaking them down. Look at any food label and you will see several classes of biochemicals along with nutritional information. Of these types of compounds, carbohydrates and fats are your body's main sources of chemical energy.

Carbohydrates and fats are biochemicals.

Carbohydrates and fats are main components of foods and provide energy when broken down. Carbohydrates are sugars and starches: -Monosaccharides - glucose, galactose, fructose -Disaccharides - sucrose, maltose, lactose -Polysaccharides - starches, glycogen Glucose (C6H12O6) is a six-sided ring structure with OH groups in specific places above and below the ring. Lipids include solid fats, liquid oils, and solid waxes: -Triglycerides - glycerol plus three fatty acids (fats, oils) -Phospholipids - phosphate head and two fatty acids -Steroid - multiringed structures -Waxes - long-chain alcohol plus long-chain fatty acid

Carbohydrates include sugars and starches.

Carbohydrates are the main source of energy that your body uses. Carbohydrates get their name from carbon and water, which they yield when burned. They include sugars and starches. The sugars can be simple sugars, called monosaccharides , such as glucose and fructose. Carbohydrates with two sugars, such as sucrose (table sugar), maltose, and lactose are called disaccharides Starches are large, biological polymers like those found in grains (corn starch) and vegetables (potato starch). They are formed from many sugar monomers and are called polysaccharides. -A starch is built unit by unit from simple sugars.

Sugar monomers link together to form polysaccharides.

Carbohydrates are your body's major source of energy. Your cells break down glucose for chemical energy. But not all glucose gets broken down. After a meal, when your body absorbs glucose from your food, excess glucose gets stored. Your liver and muscles combine glucose monomers together in long straight and branched polysaccharide chains called glycogen. Individual glucose units can later be broken off and metabolized. Plants do the same thing to form starches. Polysaccharides allow you to store numerous glucose molecules in a small space. Plants also make a polysaccharide called cellulose in their cell walls. Cellulose makes up paper and wood.

Carbohydrates and fats provide energy for your body.

The major constituents in food are organic molecules of carbohydrates and fats. Your body breaks down and stores these molecules to provide chemical energy. One carbohydrate in particular, glucose, is closely regulated by your body, and disorders of this regulation lead to the disease diabetes.

Triglycerides are fats and oils that store energy.

Triglycerides are the most common lipids. Fats and oils are triglycerides A triglyceride consists of a glycerol molecule that is bound to three long-chain fatty acids. The OH groups of glycerol react with the COOH groups of fatty acids to form the triglyceride via a condensation reaction. Depending on the types of fatty acids, triglycerides can be saturated (no double bonds) or unsaturated (one or more double bonds).

Phospholipids make up cell membranes.

Unlike triglycerides, phospholipids have a structural function. They make up cell and organelle membranes in your body. A phospholipid consists of two fatty acids bound to a phosphate portion of the molecule. Fatty acids are long-chain alkane- or alkene-type molecules and are not soluble in water. However, the phosphate "head group" is soluble. So phospholipids in membranes arrange themselves in a double layer or bilayer, with the fatty acids facing each other inward and the phosphate head groups facing the water outward (almost like a peanut butter sandwich, with phosphate head groups as bread and fatty acids as the peanut butter inside). These phospholipid bilayer membranes form barriers that separate compartments within a cell.

Fats and oils are types of lipids.

Your body stores energy not only in carbohydrates, but also in fats. Your body absorbs fats from the food you eat and stores them in muscle tissue, the abdomen, the hip area, and the liver. When needed, you mobilize fats from these areas and break them down for energy. Per mole, you get more energy from fat than you do from carbohydrates. Fats, along with oils and waxes, are actually organic compounds called lipids. Lipids have a more complex structure than carbohydrates and are larger molecules. Lipids include triglycerides, phospholipids, and steroids such as cholesterol. *Lipids, such as this fat molecule, are not soluble in water.

Polysaccharides

a carbohydrate composed of many simple sugar molecules bonded together in an unbranched or branched chains

Disaccharides

a carbohydrate molecule composed of two monosaccharides bonded together

Monosaccharides

a simple sugar

Carbohydrates

organic molecules that either are simple sugar molecules or are composed of simple sugar molecules connected in an unbranched or branched chain, with a ratio of carbon to hydrogen to oxygen atoms of about 1:2:1

Glucose is a common monosaccharide.

-Glucose, which has the chemical formula C6H12O6 , is the source of energy for all living things. It is broken down during glycolysis and is then either metabolized in the presence of oxygen in a process called aerobic respiration, or metabolized in the absence of oxygen, a process called anaerobic respiration. -Galactose, a different monosaccharide, is found in milk. Another monosaccharide, fructose, is found in most fruits and has the same formula as glucose, but is a five-sided ring structure.

Monosaccharides combine to form disaccharides.

-Like other organic molecules, carbohydrates can form polymers. For example, the disaccharide maltose is formed from two glucose molecules. The hydroxyl groups on a carbon atom of one glucose and a carbon of another glucose react. Water is released as a condensation reaction occurs. -The remaining portions form a covalent bond called a glycosidic bond that holds the two glucose molecules together. -Maltose, found in grains such as barley, is used in brewing. Table sugar, sucrose, is a disaccharide of glucose and fructose. Lactose, or milk sugar, is a disaccharide consisting of glucose and galactose.