BCHM 307 1st EditionExam # 2 Study Guide Lectures: 16 - 26Lecture 16 (February 23)How are carbohydrates classified and named?Carbohydrates are classified based upon how many sugars they contain. Monosaccharides contain one sugar, disaccharides two, ect… Monosaccharides have the formula Cn(H2O)n. Monosaccharides are first named based on how many carbons they contain, normally 3 to 6. 3 carbon sugars are called trioses, 4 carbon are called tetroses, 5 carbon are called pentoses and 6carbon hexoses. Monosaccharides are also named depending on if they contain an aldehyde or ketone groups. Combined a monosaccharide could be called an aldotriose or ketohexose. How do you draw a Fischer Projection of a monosaccharide?The most oxidized carbon is placed at the top of the drawing. Vertical lines indicate molecules extending behind in 3-D space. Horizontal lines indicate molecules extending out frontwards. The carbons go from most oxidized at the top to the least oxidized at the bottom. How are monosaccharides classified and named based on chirality?All monosaccharides are chiral and have stereoisomers. They are named either D- or L- isomers, with D being the most common in nature. They are classified based upon the penultimate carbon. When the hydroxyl group is on the right, it is called D-. When the hydroxyl group is on the left, it is called L-. How are Hayworth Projections drawn? They are drawn using the Fischer projection, but in a cyclic manner. The groups on the right hand side of the Fischer projection will face upwards in the Hayworth. The groups on the left will face downwards. Hayworth projections can either be either alpha or beta anomers. Looking at the number 1 carbon, if the hydroxyl group is facing upwards it is a beta anomer. If the hydroxyl group is facing downwards, it is an alpha anomer. What are the three main polysaccharides and what are their compositions?Starch or amylose is a helical shaped structure. It contains alpha (1,4)- linked glucose polymers. Amylase hydrolyzes this bond to break down starch. Starch has a nonreducing end and a free anomeric carbon end.Glycogen also has alpha (1,4) linked polymers of glucose. Glycogen is highly hydrated and not tightly packed. Glycogen contains alpha (1,6)-linked branches as well. Glycogen acts as a storagevessel. Cellulose is a beta (1,4)-linked polymer of glucose. Cellulose is a planar sheet. Cellulase hydrolyzes this bond to break down cellulose. Animals do not contain this enzyme. Lecture 17 (February 25)What are lipids and how are they used?Lipids are either amphiphilic or hydrophobic molecules. Most are insoluble in water but are soluble in organic solvents and other lipids. They can be highly compacted. Lipids are used as storage molecules, as parts of membranes, as protection, and hormones. What is a saponifiable lipid?It is a lipid that can be used to make soap. They have ester linked fatty acids and polar linked head groups. What are the properties of fatty acids?They are long chain of carboxylic acids. They contain 12 to 20 carbon atoms that are added on inpairs. They have polar head groups. They often have double bonds in the cis form. Cis ones havea kink that makes them not pack together as well. What influences the melting point of fatty acids?Shorter chain length means a lower melting point. The more unsaturated fatty acids have lower melting points.Lecture 18 (February 27)What are triacylglycerols?Saponifiable lipids made from 3 fatty acids ester linked to glycerol. They can be densely packed together. They function as storage lipids. They are non-polar, without any hydrogen bonds. Triacylglycerols are not hydrated and more reduced than carbohydrates. Hydrogenation can produce solid versions of triacylglycerols through reducing the cis-double bonds. When done chemically, trans-fatty acids are produced as byproducts.What are phosphoacylglycerols?They are membrane lipids. They contain phosphatidic acid. They are amphiphilic.What are sphingolipids?They are also membrane lipids. The core structure is a long chain amino alcohol called a sphingosine. This is amide linked with a fatty acid to form a ceramide. They are amphiphilic. What are non-saponifiable llipids?These do not have ester linkages. Cholesterol is a common membrane lipid example. Sterols are also an example. Many sterols are hormones. Lecture 19 (March 2)What is the fluid mosaic model?It is a model of a membrane’s structure. It contains a mosaic of lipids and proteins. The membrane is fluid in its functional state. What is the function of the membrane?It separates the cytoplasm from the environment. It provides a system for uptake of nutrients and compounds. It acts as a receptor to mediate interactions with the environment. It also provides the environment for catalysis.What is the composition of a lipid membrane?It has lipid bilayers. The fatty acids face inwards and the polar head group’s hydrogen bond with water and face outwards. They are mobile. Shorter fatty acid chains are more fluid. The less saturated fatty acid chains are also more fluid. They have integral membrane proteins. These areembedded in the membrane and are only removable with a strong detergent. Peripheral membrane proteins are not embedded in the membrane and have weak interactions. They can be removed with mild agents. Lecture 20 (March 4)How are the nitrogenous bases broken into categories?Adenine and guanine are purines. Cytosine, thymine, and uracil are pyrimidines.What are nucleosides?They are nitrogenous bases N-glycosidic-ally linked to a ribose or deoxyribose molecule. They are named based on the nitrogenous base present.What are nucleotides?They are nucleosides that have up to three phosphates added to them.What are similarities and differences between DNA and RNA?DNA is made from deoxyribonucleotides. Both have the same backbone. Both have nucleotides linked together with phosphodiester bonds. Both have directionality, 5’ to 3’. RNA is made from ribonucleotides.What do AZT and DDI do?They are used in medicine to fight cancer. They disrupt DNA production by preventing the adding of the next nucleotide through elimination of the free hydroxyl group.How do the bases hydrogen bond with each other?Guanine can form 3 hydrogen bonds with cytosine. Adenine can form 2 hydrogen bonds with either thymine in DNA or uracil in RNA. How is DNA structured?It is a double helix structure through hydrogen bonds. The strands are complementary and antiparallel to each