This gives cellulose its rigidity and high tensile strength—which is so important to plant cells. Because of the way the glucose subunits are joined, every glucose monomer is flipped relative to the next one resulting in a linear, fibrous structure.
Carbohydrates serve various functions in different animals. Arthropods have an outer skeleton, the exoskeleton, which protects their internal body parts.
This exoskeleton is made of chitin, which is a polysaccharide-containing nitrogen. Chitin is also a major component of fungal cell walls. Fats and oils, which may be saturated or unsaturated, can be unhealthy but also serve important functions for plants and animals. Fats have important functions, and many vitamins are fat soluble. Fats serve as a long-term storage form of fatty acids and act as a source of energy. They also provide insulation for the body. A fat molecule consists of two main components: glycerol and fatty acids.
Glycerol is an alcohol with three carbons, five hydrogens, and three hydroxyl OH groups. Fatty acids have a long chain of hydrocarbons with a carboxyl group attached and may have carbons; however, most of them have In a fat molecule, the fatty acids are attached to each of the three carbons of the glycerol molecule with an ester bond through the oxygen atom.
During the ester bond formation, three molecules are released. Since fats consist of three fatty acids and a glycerol, they are also called triacylglycerols or triglycerides. Triacylglycerols : Triacylglycerol is formed by the joining of three fatty acids to a glycerol backbone in a dehydration reaction. Three molecules of water are released in the process.
Fatty acids may be saturated or unsaturated. In a fatty acid chain, if there are only single bonds between neighboring carbons in the hydrocarbon chain, the fatty acid is said to be saturated. Saturated fatty acids are saturated with hydrogen since single bonds increase the number of hydrogens on each carbon.
Stearic acid and palmitic acid, which are commonly found in meat, are examples of saturated fats. When the hydrocarbon chain contains a double bond, the fatty acid is said to be unsaturated. Oleic acid is an example of an unsaturated fatty acid. Most unsaturated fats are liquid at room temperature and are called oils.
If there is only one double bond in the molecule, then it is known as a monounsaturated fat; e. If there is more than one double bond, then it is known as a polyunsaturated fat; e.
Unsaturated fats help to lower blood cholesterol levels whereas saturated fats contribute to plaque formation in the arteries. Unsaturated fats or oils are usually of plant origin and contain cis unsaturated fatty acids. Cis and trans indicate the configuration of the molecule around the double bond. If hydrogens are present in the same plane, it is referred to as a cis fat; if the hydrogen atoms are on two different planes, it is referred to as a trans fat.
Fatty Acids : Saturated fatty acids have hydrocarbon chains connected by single bonds only. Unsaturated fatty acids have one or more double bonds.
Each double bond may be in a cis or trans configuration. In the cis configuration, both hydrogens are on the same side of the hydrocarbon chain. In the trans configuration, the hydrogens are on opposite sides. A cis double bond causes a kink in the chain.
In the food industry, oils are artificially hydrogenated to make them semi-solid and of a consistency desirable for many processed food products. During this hydrogenation process, gas is bubbled through oils to solidify them, and the double bonds of the cis-conformation in the hydrocarbon chain may be converted to double bonds in the trans-conformation.
Margarine, some types of peanut butter, and shortening are examples of artificially-hydrogenated trans fats. Many fast food restaurants have recently banned the use of trans fats, and food labels are required to display the trans fat content.
Essential fatty acids are fatty acids required for biological processes, but not synthesized by the human body. Consequently, they have to be supplemented through ingestion via the diet and are nutritionally very important. Omega-3 fatty acid, or alpha-linoleic acid ALA , falls into this category and is one of only two fatty acids known to be essential for humans the other being omega-6 fatty acid, or linoleic acid. These polyunsaturated fatty acids are called omega-3 because the third carbon from the end of the hydrocarbon chain is connected to its neighboring carbon by a double bond.
Salmon, trout, and tuna are good sources of omega-3 fatty acids. Research indicates that omega-3 fatty acids reduce the risk of sudden death from heart attacks, reduce triglycerides in the blood, lower blood pressure, and prevent thrombosis by inhibiting blood clotting. They also reduce inflammation and may help reduce the risk of some cancers in animals.
Omega Fatty Acids : Alpha-linolenic acid is an example of an omega-3 fatty acid. It has three cis double bonds and, as a result, a curved shape. For clarity, the carbons are not shown. Each singly bonded carbon has two hydrogens associated with it, also not shown. DNA and RNA are nucleic acids that carry out cellular processes, especially the regulation and expression of genes. DNA is the genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals.
It is found in the nucleus of eukaryotes and in the chloroplasts and mitochondria. In prokaryotes, the DNA is not enclosed in a membranous envelope, but rather free-floating within the cytoplasm. The entire genetic content of a cell is known as its genome and the study of genomes is genomics. In eukaryotic cells, but not in prokaryotes, DNA forms a complex with histone proteins to form chromatin, the substance of eukaryotic chromosomes. A chromosome may contain tens of thousands of genes.
Many genes contain the information to make protein products; other genes code for RNA products. The other type of nucleic acid, RNA, is mostly involved in protein synthesis. In eukaryotes, the DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell. Each nucleotide is made up of three components:.
Glucose is a building block of the disaccharides lactose and sucrose cane or beet sugar , of oligosaccharides such as raffinose and of polysaccharides such as starch and amylopectin, glycogen or cellulose. For most animals, while glucose is normally obtained from the diet, it can also be generated via gluconeogenesis.
Gluconeogenesis is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of the kidneys. In humans the main gluconeogenic precursors are lactate, glycerol which is a part of the triacylglycerol molecule , alanine and glutamine.
Belongs to the class of organic compounds known as hexoses. These are monosaccharides in which the sugar unit is a is a six-carbon containing moeity. Organic compounds. The chemical properties of the different classes depend on the presence of specific functional groups. In general, the larger molecules in each class are formed by joining one or more building block molecules together in a dehydration synthesis reaction during which a molecule of water is formed for each building block added.
Large molecules are broken down into the smaller building block molecules by a reverse reaction called hydrolysis during which water is added. In this exercise you will learn about the structure and properties of carbohydrates, lipids and proteins and how to test for the presence of these organic molecules. Lipids are organic molecules that are insoluble in water and other polar solvents. Lipids are readily soluble in nonpolar solvents , such as chloroform, benzene, and ether.
Lipids include fats and oils important as energy storage compounds , phospholipids and glycolipids part of the structure of cell membranes , waxes protective surface coatings on many plants and animals , and steroids found in some cell membranes and many hormones. Fats and oils have similar structures, and both serve as energy storage molecules. At room temperature oils are liquid and fats are solid.
Both are triglycerides formed by combining a molecule of glycerol with three molecules of fatty acid. The properties of a triglyceride depend upon the structures of the fatty acids it contains.
Fatty acids are long chains containing carbon and hydrogen with a carboxyl group COOH on one end, which makes the molecule an acid,. The carboxyl group is involved in bonding each fatty acid to the glycerol molecule.
Fatty acids differ in the length of the chain and the number of double bonds between adjacent carbon atoms. If all the carbon atoms in a fatty acid chain are bonded to four different atoms no double bonds between carbon atoms , the fatty acid has a straight chain without bends or kinks. Double bonds between carbon atoms cause fatty acids chains to bend or kink. The fatty acids of saturated fats such as lard, bacon fat, or butter contain no double bonds, a maximum of hydrogen atoms, and the straight fatty acid chains pack closely together.
The fatty acids of unsaturated fats contain at least one double bond, fewer hydrogen atoms, and the fatty acid chains cannot pack as closely together because at least one of the chains has a kink or bend.
Monounsaturated fats , such as olive oil, have one double bond. Polyunsaturated fats , such as corn oil, have two or more double bonds. The less "orderly" structure of unsaturated fats is responsible for their lower melting point.
Glucose is a carbohydrate, specifically a monosaccharide. This is like saying peas are a vegetable, and more specifically a legume--a type of vegetable.
Being even more specific, glucose is a simple sugar. It is variably called grape sugar, blood sugar and corn sugar. Carbohydrates are the most abundant of the major macromolecules found in the human body. The other three are nucleic acids, proteins and lipids. Macromolecules are often viewed as polymers. Carbohydrates are involved with the storage and transportation of energy.
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