CHEM 140 Midterm: CHEM EXAM 4
CHEM 140 Midterm: CHEM EXAM 4

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California State University - Long Beach
Chemistry and Biochemistry
CHEM 140
P Pierce

Chapter 13- Carbohydrates ❖ DEFINITION ➢ 1. Provide energy for metabolic reactions ➢ 2. Serve as a source of carbon atoms for the biosynthesis of many molecules ➢ 3. Have structural elements for some cells and tissues ➢ 4. Major energy storage form for humans ➢ Produced by photosynthesis in plants, synthesized in plants, oxidized in living organisms-> respiration ➢ Classified by monosaccharides, disaccharide, oligosaccharide(3-10), and polysaccharide ❖ ALDOSES & KETOSES ➢ Aldose = Monosaccharides with an aldehyde group and many hydroxyl group ■ Triose = 3 ■ Tetrose = 4 ■ Pentose = 5 ■ Hexose = 6 ➢ Ketose = Monosaccharides with an carbonyl on the second carbon and many hydroxyl groups ❖ STEREOISOMERS ➢ Compounds with the same chemical formula that have the same connections between atoms, but the atoms have a different spatial arrangement ➢ Have the property chirality = an object that cannot be superimposed on it mirror image ● Structural isomers: molecules have bonded together in a different order ■ Chiral carbon: carbon that has four different groups attached to it ■ Chiral center: central carbon with four different groups attached ■ Any molecule that contains a chiral carbon will exist as stereoisomers ■ The number of stereoisomers can be found by 2^N (N = number of chiral carbon atoms) ➢ Enantiomers: stereoisomers that are non-superimposable images (D or L isomer) OPTICAL ISOMERS ➢ Diastereomers: stereoisomers that are not mirror images ➢ Epimers: stereoisomers that differ in configuration at only one chiral carbon ➢ Anomers: stereoisomers that differ at only the anomeric carbon (ALPHA or BETA) ❖ FISCHER PROJECTIONS ➢ D-isomer will have the hydroxyl group on the penultimate carbon (5TH CARBON) drawn on the right ➢ L-isomer will have the hydroxyl group on the penultimate carbon drawn on the left ➢ Ultimate carbon: highest numbered carbon drawn up for D isomer and down for L isomer ➢ Anomeric carbon: carbon in the carbonyl group in the CYCLIC FORM ONLY ■ Carbonyl carbon not chiral, anomeric carbon is chiral -> alpha and beta (anomers) ❖ MONOSACCHARIDES ➢ Cannot be split or hydrolyzed into smaller carbohydrates ➢ **MEMORIZE GLUCOSE, MANNOSE, GALACTOSE, FRUCTOSE,RIBOSE, DEOXYRIBOSE** ■ D-GLUCOSE: known as dextrose, grape sugar, and blood sugar ● Source of energy to fuel biochemical reactions, found in some fruits, corn syrup, honey ● Present in cellulose, starch, and glycogen ● Final product in of carbohydrate digestion and provides acetyl groups for entry into the citric acid cycle ● REGULATED by INSULIN and GLUCAGON ■ D-GALACTOSE: known as brain sugar ● Not found free in nature, component of lactose (milk sugar), found in brain tissue ● Widely distributed in plant gums and pectins, sticky polysaccharides present in plant cells ● Important in lipids called cerebrosides found in brain sugar ● Converted to glucose to provide energy and produce lactose for milk and compounds needed in brain sugar ● Galactosemia is an inherited deficiency of the enzymes needed to metabolize ■ D-FRUCTOSE: known as levulose, fruit sugar, dietary sugar ● Found in many fruits and honey ● Sweeter than sucrose, so less is required to sweeten food = fewer calories used ■ RIBOSE/2-DEOXYRIBOSE: five-carbon aldehyde sugars ● Important in biomolecules like coenzyme A, ATP, cyclic AMP and redox coenzymes ❖ REDUCING SUGARS ➢ Monosaccharides that oxidize to give a carboxylic acid ➢ Glycosides that don’t contain hemiacetal groups are not reducing sugar ➢ All cyclic monosaccharides contain the hemiacetal at C 1 or 2(fructose) ➢ Mutorotation is when alpha and B are converted to each other because a small part of the open chain is always present in solution ➢ Hemiacetal carbon=anomeric carbon ■ Cyclic sugars that differ only at the anomeric or hemiacetal carbon are anomers alpha and beta ➢ Hemiacetals react with alcohols to form acetals (two OR groups) ➢ GLYCOSIDE: A cyclic acetal formed by the reaction of a monosaccharide with an alcohol with a loss of water ➢ GLYCOSIDIC BOND: bond between the anomeric carbon of a monosaccharide and an OR group ➢ The OH groups of sugars can add phosphate groups to form phosphate esters ■ Phosphate esters of monosaccharides are reacts and products in the metabolism of carbohydrates ■ ATP phosphorylates glucose to begin glycolysis ❖ DISACCHARIDES ➢ Two monosaccharide units joined together ➢ Formed by reaction of the anomeric carbon of one monosaccharide and the OH group of another monosaccharide ➢ **MEMORIZE MALTOSE, LACTOSE, AND SUCROSE** ■ MALTOSE: known as malt sugar ● Present in fermenting grains and can be prepared by enzyme catalyzed degradation of starch ● Used as a sweetener, produced during starch digestion ● Glucose + Glucose ● Alpha- 1,4 bond ■ LACTOSE: found in milk ● Galactose + Glucose ● Beta- 1,4 bond ■ SUCROSE: known as table sugar ● From sugar cane and sugar beets ● Fructose + Glucose ● Alpha,beta-1,2 bond ● NOT A REDUCING SUGAR BECAUSE NO HEMIACETAL GROUP ❖ POLYSACCHARIDES ➢ Are polymers of d-glucose ■ Amylose = alpha-1,4 ● Energy storage polysaccharide ■ Amylopectin = alpha 1,4 with alpha-1,6 every 24-30 glucose residues ● Energy storage polysaccharide ● branched ■ Glycogen = alpha 1,4 with alpha-1,6 every 8-12 glucose residues ● Known as animal starch ● Synthesized and Stored in liver and muscle ● More branched than amylopectin ■ Cellulose = beta-1,4 ● Cannot be digested by humans because we lack cellulase enzyme that hydrolyzes the bond ■ Starch = alpha-1,4 bond ● Main storage form of glucose in plants ● 20% amylose ● 80-90% amylopectin ❖ EXTRA VOCABULARY ➢ Glycosides: cyclic hemiacetals that react with alcohols to form acetals ➢ Glycosidic Bond: bond between the anomeric carbon atom and an -OR group (ETHER BOND) Chapter 15- Lipids ❖ DEFINITION ➢ Compounds that are soluble in nonpolar solvents, but sparingly soluble in water ➢ Contain fatty acids or a steroid nucleus ■ If they don’t contain fatty acids they are STEROIDS ❖ CLASSIFICATIONS ➢ SAPONIFIABLE LIPIDS - ester or amide bonds and their susceptibility to hydrolysis using a strong base ■ Saturated fatty acids: contain only carbon-carbon single bonds ● Solids ● Hydrocarbon chains are flexible and uniform allowing them to stack together nicely ◆ HIGHER melting points ■ Unsaturated fatty acids: contain carbon-carbon double bonds ● Liquids ● Contain rigid kinks wherever they contain cis double bonds, which makes it difficult for them to fit next to each other ◆ LOWER melting points ● Monounsaturated fatty acids: contain only one carbon-carbon double bond ● Polyunsaturated fatty acids: contain more than one carbon-carbon double bond ◆ Linoleic and linolenic acids are essential to the human diet because the body cannot synthesize them and needed for synthesis of other lipids ❖ TYPES OF LIPIDS ➢ WAXES ■ Mixture of a fatty acid and long chain alcohol ester ■ Simplest fatty acid esters ➢ FATS AND OILS- TRIACYLGLYCEROLS ■ Triesters of glycerol ■ Known as triacylglycerols or triglycerides ● NONPOLAR hydrophobic molecules with no ionic charges ➢ OILS= a mixture of triacylglycerols that is liquid because it contains a high proportion of unsaturated fatty acids ■ Plant source ➢ FATS: Mixture of triacylglycerols that is solid because it contains a high proportion of saturated fatty acids ■ Comes from animal sources ■ The more double bonds, the harder it is to SOLIDIFY ➢ CHEMICAL REACTIONS OF TRIACYLGLYCEROLS ■ Double bonds in vegetable oils can be HYDROGENATED to yield saturated fats ■ During hydrogenation, some cis double bonds are converted to TRANS double bonds, which behave like saturated fats in the body ■ Melting point INCREASES IN PARTIAL HYDROGENATION ● Get softer product like butter. Full hydrogenation gives brittle product ■ HYDROLYSIs of fats and oils is carried out by strong bases in saponification ➢ Micelle ■ A spherical cluster formed by the aggregation of soap or detergent molecules so that their hydrophobic ends are in the center and their hydrophilic ends are on the surface ❖ CATEGORIES: CELL MEMBRANE LIPIDS: GLYCEROPHOSPHOLIPIDS, SPHINGOLIPIDS, CHOLESTEROL ➢ PHOSPHOLIPIDS ■ A Lipid that has an ester link between phosphoric acid and alcohol (glycerol or sphingosine) ■ GLYCEROPHOSPHOLIPIDS (amino alcohols) ● **MEMORIZE SERINE, ETHANOLAMINE, CHOLINE** ● With a phosphate ester link to choline are phosphatidylcholines or LECITHINS: CHOLINE ◆ They are emulsifying agents- they surround droplets of nonpolar liquids and suspend them in water ◆ CEPHALINS: ethanolamine or serine ■ SPHINGOMYELINS ● Sphingosine derivatives with a phosphate ester group at c1 of sphingosine ➢ SPHINGOLIPIDS ■ GLYCOLIPIDS derived from sphingosine ● Contain no phosphate group but have a monosaccharide or oligosaccharide attached ● Extend their carbohydrate segments into the fluid surrounding the cells ● Function as receptors that are essential for recognizing chemical messengers, other cells, pathogens, and drugs ◆ CEREBROSIDES ➢ Glycolipids which contain a monosaccharide are particularly abundant in nerve cell membranes in the brain ➢ Ganglioside: glycolipids outside of the brain that contain oligosaccharides ■ Sugar is D galactose ■ Also found in other cell membranes ■ SPHINGOMYELINS ● Sphingosine derivatives with a phosphate ester group at c1 of sphingosine ● Major components of the myelin sheath, coating of nerve fibers, and are present in brain tissue Polar heads and hydrophobic tails of phospholipids and glycolipids allow them to form membrane bilayers that act as barrier that separate the interior or the cells from the exterior ➢ CHOLESTEROL (also cell membrane lipid) ■ the most abundant steroid in the body ● Has methyl groups, alkyl chain, and -OH attached ■ NEEDED for cell membranes, brain and nerve tissue, synthesis of steroid hormones, Vitamin D ● Obtained from meats, milks, and eggs ■ Clogs arteries when LDL forms high levels of plaque ■ Considered elevated if plasma cholesterol is over 200 mg/dL ➢ Synthesized in the liver and obtained from foods ➢ Cholesterol is hydrophobic and nearly a flat molecule ● Distributed among hydrophobic tails of PHOSPHOLIPIDS ● More rigid than these hydrophobic tails, so they help maintain the structure of the membranes ● STEROIDS ◆ Major functions besides cholesterol: hormones and as the bile acids that are essential for the digestion of fats and oils ◆ Steroid nucleus: consists of 3 cyclohexane rings and 1 cyclopentane ring ◆ NO FATTY ACIDS ● Bile salts: ◆ Synthesized from cholesterol in the liver ◆ Stored in the gall bladder ◆ Secreted into small intestine ◆ Mix with water-insoluble fats and oils in our diet ◆ Bile salts break down large globules of fat into smaller droplets ◆ Smaller droplets containing fat have larger surface area to react with lipases ❖ EICOSANOIDS: PROSTAGLANDINS AND LEUKOTRIENES LOCAL HORMONES ➢ A group of compounds derived from 20-carbon unsaturated fatty acids (eicosanoic acids) and synthesized throughout the body ➢ Function as short-lived chemical messengers that act near their points of synthesis ➢ Ex: prostaglandins and leukotrienes are two classes of eicosanoids ■ Prostaglandins contain cyclic structure which leukotrienes lack. ➢ Synthesized from arachidonic acid, which is synthesized from linolenic acid, which is why linolenic acid is one of two essential fatty acids ➢ Prostaglandins have a RANGE OF BIOLOGICAL EFFECTS: ■ Lower blood pressure, influence platelet aggregation during blood clotting, stimulate uterine contractions, lower the extent of gastric secretions ● Pain and swelling that accompany inflammation CH 16: Proteins, Amino Acids, Enzymes 1. Amino acids and proteins ● Proteins are polymers of amino acids ● Proteins are important in the biosynthesis of enzymes, hormones, some blood components, maintenance and repair of tissue, synthesis of new tissue, and for energy ● Play structural roles in the body, store small molecules, regulatory functions, and provide protection. ○ STRUCTURAL: provide structural components, ○ CONTRACTILE: movement of muscles, ○ TRANSPORT: carry essential substances throughout the body, ○ STORAGE: store nutrients, ○ HORMONE: regulate body metabolism, ○ ENZYME: catalyze biochemical reactions in the cells, ○ PROTECTION: recognize and destroy foreign substances ● An Amino acid is an organic compound with an NH2 and COOH group ○ Amino acids found in proteins are alpha amino acids, since the amino group is bonded to the alpha carbon of the carboxylic acid chain ○ The 20 amino acids in the body are called standard amino acids ● AMINO ACIDS ○ Building blocks of protein ○ Ionized in solution -> zwitterion ○ Each contain a different side group ○ Chemical nature of the R group distinguished the different alpha amino acids ○ Classified as: ■ Acidic: carboxylic acid ■ Basic: amine ■ Nonpolar: H, alkyl, aromatic ■ Polar neutral: alcohol, thiol, amide ● The sequence of amino acids in a protein and the chemical nature of their side groups determine the function/ allow them to perform their function ● Shape and function is often determined by intermolecular forces ● Noncovalent forces act between different molecules or on different parts of the same molecule ● POLAR and NONPOLAR AMINO ACIDS ○ Nonpolar side chains=hydrophobic ○ Often gather into clusters to ensure a water free environment-pocket within a large protein molecule ● Polar, acidic and basic side chains are hydrophilic and interact with water molecules often ● The attractions between the water molecules and the hydrophilic groups on the surface of proteins give water solubility to the proteins ❖ 10 essential amino acids that we don’t have to memorize ➢ Are not synthesized by the body but are in meat and dairy products ❖ ZWITTERIONS ➢ The form of amino acids that we are studying- have charged NH3+ and COO- groups ➢ Forms when NH2 and COOH ionize in water ➢ Due to the fact that amino acids are zwitterions, they have many salt like characteristics: ■ Crystal formation, high melting points, soluble in water, ➢ Acidic solution: amino acids accept protons on COO- group and become COOH, NH3+ stays ➢ Basic solution: amino acids lose protons from NH3+ group and become NH2. COO- stays ❖ PEPTIDE BONDS ➢ When the carboxyl group and amino group of two different amino acids react, an amide bond is formed that is called a PEPTIDE BOND ➢ PEPTIDES are amino acid sequences of up to 50 amino acids in length, and many amino acids can be linked to give chains of peptide bonds ➢ The left end of the peptide contains the N-TERMINUS and the right side of the peptide contains the C-TERMINUS ➢ POLYPEPTIDES are intermediate chain length polymers ➢ PROTEINS are polymers with more than 50 amino acids ➢ AMINO ACID RESIDUE is one amino acid that is a part of a polymer ❖ PROTEIN SHAPES ➢ FIBROUS PROTEINS are long rod shaped or string like molecules that intertwine to form fibers or sheets such as collagen, elastin, and keratin ■ Tough and insoluble ■ Alpha keratins in hair and nails are an example ■ Hardness, flexibility, and stretchiness varies with the number of disulfide bonds ■ Large amounts of beta pleated sheets ➢ GLOBULAR PROTEINS (tertiary structure) are spherical shaped proteins that are water soluble. ■ Chains are folded into compact, globe like shapes ■ Structures are often made of sections of alpha helix and B sheet folded in on itself ■ Water solubility allows them to travel through the blood and other bodily fluids ■ Carry out the work of the cells: synthesis, transport, metabolism ➢ SIMPLE PROTEINS: contain only amino acid residues ➢ CONJUGATED PROTEINS contain amino acid residues and either an organic or inorganic component- a prosthetic group PROSTHETIC GROUP CLASS OF CONJUGATED PROTEIN Metal Ion Metalloprotein Nucleic Acid Nucleoprotein Phosphate group Phosphoprotein Lipid Lipoprotein Carbohydrate Glycoprotein Heme Group Hemoprotein ❖ PRIMARY STRUCTURE OF PROTEINS ➢ Connected by peptide bonds ➢ A PEPTIDE is the linking of two or more amino acids by peptide bonds ➢ We can write an amidation reaction for the formation of the peptide ➢ The particular sequence of amino acids ➢ Is the backbone of a peptide chain or protein ➢ Insulin was the first protein to have its primary structure determined ➢ CONSERVATIVE SUBSTITUTION: replace an amino acid with a similar amino acid, not a huge change ➢ NONCONSERVATIVE SUBSTITUTION: Huge change in replacing an amino acid that affects both the structure and function of the protein ❖ SECONDARY PROTEIN STRUCTURE ➢ SECONDARY STRUCTURE constitutes the spatial arrangement of the polypeptide backbo
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