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by: Emily Ellis


Emily Ellis

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These notes cover what will be on our first exam. They cover modules 1-4 and this includes detailed notes pulled from the lectures
Nikki Bush
Study Guide
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This 27 page Study Guide was uploaded by Emily Ellis on Sunday September 25, 2016. The Study Guide belongs to NHM 361 at University of Alabama - Tuscaloosa taught by Nikki Bush in Fall 2016. Since its upload, it has received 4 views. For similar materials see Biochemistry in Nutrition and Food Sciences at University of Alabama - Tuscaloosa.

Popular in Nutrition and Food Sciences


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Date Created: 09/25/16
Saturday, September 24, 2016 Exam 1 S.G. MODULE 1 1 Saturday, September 24, 2016 2 Saturday, September 24, 2016 3 Saturday, September 24, 2016 MODULE 2 KEY TERMS: • INTRACELLULAR FLUID- body fluid located within the cells EXTRACELLULAR FLUID- body fluid located outside the cells • INTERSTITIAL FLUID- fluid surrounding individual cells and fluid in the lymph vessels • PLASMA- the liquid portion of whole blood 4 Saturday, September 24, 2016 • HYDROPHILIC- water loving molecules that have a sufficient number of polarized bonds or ionized groups in order for it to dissolve in water • HYDROPHOBIC- molecules that are electrically neutral and are not attracted to the (+) and (-) charges of H2O • AMPHIPATHIC MOLECULES- are those that consist of both hydrophilic and hydrophobic parts (think fatty acids) • HYDROLYSIS- breaking of chemical bonds • DEHYDRATION SYNTHESIS- formation of chemical bonds • HYPERKALEMIA- serum potassium is too high • HYPOKALEMIA- serum potassium is too low [these may result in dangerous cardiac arrhythmias] • HYPERNATREMIA- high serum sodium [sign of dehydration] • HYPONATREMIA- low serum sodium [may result from diuretic medications or rarely, from excessive water intake during exercise] • • HYPERPHOSPHATEMIA- high serum phosphate • HYPOPHOSPHATEMIA- low serum phosphate [concentrations of Na+ & Cl- are regulated in the blood to maintain osmotic pressure (also known as osmolality) of blood plasma ..edema is an example of osmotic imbalance]
 • ANTIDIURETIC HORMONE (ADH)- reduces the excretion of water in urine by increasing reabsorption of water by kidney 5 Saturday, September 24, 2016 tubules, resulting in concentrated urine; it is also known as “vasopressin” • ALKALOSIS- high blood pH [is very serious and could result in death] • ACIDOSIS- low blood pH [is very serious and could result in death] • RESPIRATORY ALKALOSIS- occurs when a person is hyperventilating and is expelling too much CO2 • RESPIRATORY ACIDOSIS- results from slow, shallow breathing and retention of CO2; example is pneumonia • METABOLIC ALKALOSIS- occurs when the body has lost too much acid; example is vomiting • METABOLIC ACIDOSIS- occurs with the loss of too much bicarbonate or buildup of acid in the blood for a reason other than hypoventilation; examples are alcholism, kidney disease, or severe dehydration KEY CONCEPTS: water is the most abundant molecule in the human body accounting for 2/3 of total body weight —> body water can be categorized as intracellular or extracellular fluid —> can be divided further into interstitial fluid and plasma Unique Properties of Water: 1. water cushions and lubricates the body’s tissues and organs 2. water is a great solvent due to its polarity 6 Saturday, September 24, 2016 3. water is an excellent transport medium of nutrients to cells and tissues • gas exchange is a critical functions of the blood • oxygen is carried from lungs to tissues 
 • because oxygen is insoluble in plasma, most oxygen is carried in RBCs bound to hemoglobin 
 • carbon dioxide is a common byproduct of cellular metabolism 
 • CO2 must be transported from tissues to the lungs to be exhaled 
 • CO2 is more soluble in plasma than oxygen, so about 5% can be transported unchanged in plasma 
 • another 10-25% of CO2 binds to plasma proteins or proteins portion of hemoglobin for transports 
 • most CO2 in plasma (about 75%) is in the form of bicarbonate ions (HCO3-) • can diffuse back and forth between plasma and RBC 7 Saturday, September 24, 2016 • HCO3- and Cl- ions move in and vice versa in order to maintain charge neutrality and osmotic balance between plasma and RBC... this is called the CHLORIDE SHIFT 
 • HCO3- ions entering RBCs can combine with the H+ ions to form carbonic acid (H2CO3) 
 • an enzyme inside RBCs, carbonic anhydrase, promotes the breakdown of H2CO3 to CO2 & H2O • this action is reversible 
 • • when blood reaches the lungs, the low pressure of CO2 in the lungs favors this reaction so that H2CO3 is broken down to CO2 & H2O 
 • CO2 diffuses from RBCs to alveoli (air sacs) of the lungs where it is expelled as exhaled air 
 Key Electrolytes: 
 Sodium (Na+) : principle extracellular cation 
 Potassium (K+) : principle intracellular cation 
 Chloride (Cl-) : principle extracellular anion 
 Phosphate ( mainly as HPO4 2-) : principle intracellular anion 
 • these are called “electrolytes” because they can generate charge across plasma membranes 8 Saturday, September 24, 2016 
 • fluid & electrolyte balance is very important to human health 
 Homeostatic regulation of fluid balance in the body: • the hypothalamus regulates the sensation of thirst • fluid is lost through urine, air exhaled from the lungs, through the skin, & through feces the kidneys also play a role in fluid and electrolyte balance as • well as acid-base balance • urine is ordinarily about 96% water and 4% waste products 9 Saturday, September 24, 2016 • pH of urine is tightly maintained between 7.35-7.45 • veggies & fruits will make the urine more alkaline while high- protein foods will make the urine more acidic • acids and bases dissociate in water & conduct an electric current • acids release H+ & therefore are proton donors 
 HCl —> H(+) + Cl(-) • bases accept H+ & are proton acceptors 
 NaOH —> Na(+) + OH(-) • water is an acid & a base • it dissociates to form a hydroxide ion & proton, which bonds to another r water molecule 
 H2O <—> HO(-) + H(+) • the concentration of H+ in solution is expressed by pH 
 pH = -log[H+] • so solutions with a high [H+] have a low pH, & solutions with a low [H+] have a high pH • pH runs on a scale from 0-14 with 7 being neutral compounds that contain a carboxyl group (R-COOH) are acids, • specifically carboxylic acids • normal blood pH is maintained tightly at 7.35-7.45 10 Saturday, September 24, 2016 • buffers work in the blood, the respiratory system, and the urinary system & they all work together to maintain the acid-base balance in the blood 
 Buffer Control of Blood pH: • bicarbonate, phosphate, & plasma proteins in the blood all function as buffer systems • these buffers prevent major swings in pH of the blood when acids or bases are introduced • the bicarbonate buffer system consists of a mix of bicarbonate ions (HCO3-) & carbonic acid (H2CO3) • acids and bases tend to dissociate, releasing H+ or OH- ions in the blood 
 Respiratory Control of Blood in pH: • respiratory system helps maintain acid-base balance in the blood by regulating how much CO2 & H2O are exhaled 
 • the more CO2 & H2O that are exhaled, the more carbonic acid is removed from the blood, which raises the blood pH to a more alkaline level • increases in CO2 induces faster and deeper breathing (hyperventilation), so that more CO2 will be expelled & blood pH normalizes • likewise, decreases in CO2 causes slower respiration rates (hypoventilation), so that more CO2 will be retained. Less 11 Saturday, September 24, 2016 CO2 exhaled = more carbonic acid = decrease in pH 
 Urinary Control of Blood pH: • the kidneys respond to increases and decreases in blood pH by excretion of ions by urine • the distal tubes of kidney nephrons are sensitive to blood pH • if blood is too acidic, the renal tubules excrete excess H+ ions & conserve bicarbonate ions (HCO3-) • if blood is too basic, renal tubules excrete HCO3- & conserve H+ • oxygen binds to the iron (Fe2+) portion of hemoglobin for transport from the lungs (alveoli) to the cells • CO2 can be transported in 3 different ways 1.unchanged in the plasma (5%) 2.bound to the hemoglobin or plasma proteins (10-25%) - doesn’t compete with oxygen to bind to hemoglobin since CO2 is binding to protein portions 3.most transports as bicarbonate ions (HCO3-) 12 Saturday, September 24, 2016 Quiz 2: Questions & Answers A fatty acid is an example of a (n) ______ molecule? amphipathic A decrease in blood pH below normal will stimulate: hypoventilation The normal pH of extracellular fluid and blood is: 7.4 High serum potassium is called: hyperkalemia Carbon dioxide is transported in the bloodstream chiefly in the form of: HCO3- Bicarbonate ions which diffuse into and out of red blood cells are replaced by ____ Cl- 7. Which of the following is the major cation of plasma and extracellular fluid? Na+ 8. An increase in vasopressin secretion will result in ____ water excreted in urine More 13 Saturday, September 24, 2016 9. Which of the following is NOT one of the properties of water? Atoms of adjacent water molecules repel one another 10. A condition of high blood pH for a reason other than respiratory dysfunction would be called? Metabolic alkalosis MODULE 3 Biomolecule = an organic compound essential for life (e.g., carbohydrates, proteins, lipids) Carbohydrates, proteins, and fats are also called macronutrients. •required by the body in relatively large amounts Main functions of carbohydrates: •Provide energy through the iroxidation •Supply carbon atoms for synthesis of other organic molecules •Serve as a storage form of chemical energy(i.e. glycogen) •Act as structural components (e.g.,deoxyribose of DNA) 14 Saturday, September 24, 2016 Structure of carbohydrates: • Monosaccharides – also called “simple sugars” • Disaccharides = 2 monosaccharides joined by a dehydration reaction; so, the opposite reaction, a hydrolysis reaction, will break a disaccharide down into 2 monosaccharides • Oligosaccharides = a short chain of monosaccharide units (oligo = few) • Polysaccharides = a long chain of monosaccharide units Structure of Carbohydrates: •  Carbohydrate molecules have a large number of functional groups attached to chains. For example, notice that the 5-C chain of ribose has a functional group at every carbon of the chain. •  In addition to the hydroxyl functional group (-OH), monosaccharides have a carbonyl functional group (C=O) , making them aldehydes or ketones. 15 Saturday, September 24, 2016 Stereochemistry of Carbohydrates: • stereoisomers are compounds with the same molecular and structural formula but different spatial arrangements of atoms. • enantiomer is one of two stereoisomers that is a mirror image of another. - Enatiomers are called “chiral” because the mirror images cannot be superimposed on one another ▯ ▯ Fischer Projections: • Fischer projection = a method of representing 3-dimensional shapes of chiral molecules in 2 dimensions - In Fischer projections of carbohydrates, the carbonyl group is placed at or near the top of the molecule. Chiral carbons are represented by the intersection of two lines. The two horizontal bonds of each chiral carbon are coming out of the page toward you. The two vertical bonds of each chiral carbon are bending back into the page away from you. 16 Saturday, September 24, 2016 D and L Enantiomers: •  Monosaccharides are given the designation “D” or “L” based on the orientation of the functional group attached to the chiral carbon farthest from the carbonyl group (C=O) of a Fischer projection. 
 •  A capital L indicates that the functional group is on the left side of the farthest chiral carbon (“L” for left). A capital D indicates the functional group is on the right. 
 •  D and L sugars are mirror images of one another. 
 17 Saturday, September 24, 2016 •  Both monosaccharides and amino acids are chiral molecules, so they can 
 be designated by either D or L. 
 •  Most naturally-occurring sugars are D isomers. • Monosaccharides may be classified based on the number of carbons they contain. For example 5-C monosaccharides are “pentoses,” 6-C monosaccharides are “hexoses,” etc. • Because monosaccharides contain an aldehyde or a keto group, they can also be classified as aldoses and ketoses Cyclic forms of monosaccharides: • Notice the many hydroxyl (-OH) groups on monosaccharides. This makes them soluble in water, and it presents an opportunity for hydrogen bonding with surrounding molecules. • In fact, the aldehyde or keto groups of a pentose or hexose can react with the hydroxyl group of a distal C to form a ring structure. This is called “cyclization.” 18 Saturday, September 24, 2016 • The cyclization of glucose into a pyranose ring is depicted on p. 198 (reaction 7.1), and cyclization of fructose into a furanose ring is depicted on p. 199 (reaction 7.3). • Pyranose ring = a six-membered sugar ring containing an oxygen atom Furanose ring = a five-membered sugar ring containing an oxygen atom Haworth structures for cyclic sugars: • Haworth structures = representations of 3-D cyclic sugars. The cyclization of glucose results in a new chiral carbon at position • 1. Thus, two stereoisomers are possible – one with the –OH group pointed up and another with the –OH group pointed down. These two stereoisomers are called anomers, and the C-1 carbon is called an anomeric carbon. • Anomers are designated as α or β forms:
 α = the –OH group at the anomeric C-1 points down β = the –OH group at the anomeric C-1 points up • Anomers differ only in the position of the –OH group attached to the anomeric carbon. By convention, the anomeric C is always drawn on the right side of a Haworth structure. Phosphate esters: Recall that hydroxyl groups (-OH) can react with acids to form • esters. Hydroxyl groups of monosaccharides frequently react with • phosphoric acid to form phosphate esters. Later in the semester, we will see these two phosphate esters, • glucose-6- phosphate and fructose-6-phosphate in important metabolic pathways of carbohydrate metabolism. 19 Saturday, September 24, 2016 Important monosaccharides: • Ribose and deoxyribose are pentoses that serve as structural components of nucleic acids (RNA and DNA). Fructose – tastes the sweetest of the monosaccharides; abundant in • fruits; present in a 1:1 ratio with glucose in honey Glucose – We will become very familiar with glucose this semester • because it is a primary source of energy for the human body. Galactose has a structure similar to glucose; the only difference • between structures is the orientation of the hydroxyl group attached to C-4. Despite similar structures, glucose and galactose have different properties. Glycosidic bonds: • The anomeric hydroxyl group of one monosaccharide can react with a hydroxyl group of another monosaccharide to form a glycosidic bond. • Glycosidic bonds join the monosaccharides to form disaccharides and polysaccharides. Disaccharides:
 • Maltose – consists of 2 glucose molecules joined together by an α(1-4) glycosidic bond • Lactose – consists of a glucose molecule joined to a galactose molecule by a β(1-4) glycosidic bond (p. 205); commonly called “milk- sugar,” lactose is the main sugar in cow’s milk and human milk; Sucrose – consists of a glucose molecule joined to a fructose • molecule by a α-1 – β-2 glycosidic bond; commonly called “table sugar” 20 Saturday, September 24, 2016 Polysaccharides: • Because of their large size, polysaccharides are not soluble in water. • Starch = polymer of glucose units; storage form of glucose in plant; amylose and amylopectin • Amylose (Fig 7.14 on p. 208) = long unbranched chain of glucose units connected by α(1-4) glycosidic bonds (the same glycosidic linkage found in maltose); Amylose breaks down into maltose, and maltose breaks down into glucose. • Amylopectin (Fig 7.17 on p. 209) = also a chain of glucose molecules, but it is not a straight chain like amylose; Intermittant α(1-6) glycosidic bonds create branch points in the molecule. Glycogen: Glycogen = the storage form of glucose in animals; similar in structure t to amylopectin, but it is more highly branched Carbohydrates that escape digestion: • Cellulose = an important structural polysaccharide that gives cell walls of plants strength and firmness. Whereas the glycosidic linkages in amylose are α(1-4) glycosidic bonds, the glycosidic linkages in cellulose are β(1-4) glycosidic bonds. • Humans do not possess the enzymes necessary to hydrolyze β(1-4) glycosidic bonds, so cellulose passes undigested through the digestive tract. Although it doesn’t provide energy to the body, this dietary fiber is beneficial for digestive health by softening stools and decreasing intestinal transit time. • Other common fibers in food include β-glucans, pectin, and lignin. 
 21 Saturday, September 24, 2016 • Resistant starches are polysaccharides the resist hydrolysis by intestinal enzymes 
 because of their physical structure rather than their chemical structure. • Certain types of fiber and resistant starches can be fermented by bacteria in the 
 colon to form short chain fatty acids that nourish colon cells. Dietary fiber may also bind cholesterol and promote its excretion MODULE 4: Lipids = nonpolar (hydrophobic) biomolecules that have low solubility in water Important lipids in the body include:
 o Triglycerides
 o Phospholipids and Sphingolipids
 o Steroids (including cholesterol)
 o Eicosanoids (including prostaglandins) Fatty acids: • Fatty acids are the fundamental building blocks of most lipids; fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end. • Most naturally occurring fatty acids have an even number of carbon atoms, typically 10-20 carbons. • Fatty acids can be oxidized to yield large amounts of energy. • Fatty acids are amphipathic; a fatty acid has a polar carboxylic acid head and a nonpolar hydrocarbon tail. 
 22 Saturday, September 24, 2016 • In aqueous solutions, free fatty acids form spherical structures called micelles. The hydrophobic hydrocarbon chains coalesce in the middle while the hydrophilic polar heads align to the exterior. Fatty acids may be saturated (only single bonds between carbon • atoms) or unsaturated (containing one or more double bonds between carbon atoms). • Monounsaturated fatty acids contain one double bond • Polyunsaturated fatty acids contain more than one double bond o Saturated fatty acids = 0 double bonds
 o Monounsaturated fatty acids (MUFAs) = 1 double bond
 o Polyunsaturated fatty acids (PUFAs) = 2 or more double bonds • The double bonds of unsaturated fatty acids usually have a cis configuration: • Saturated fatty acids can pack together tightly, but the double bonds of unsaturated fatty acids create kinks or bends that prevent tight packing. • Thus, unsaturated fatty acids are typically liquid at room temperature whereas saturated fatty acids are typically solid. Nomenclature for fatty acids: • Different systems of nomenclature are used to identify fatty acids. The Greek letter omega (ω) indicates the location of the double bond closest to the methyl (-CH3) end of the chain. • For example, linolenic acid is an omega-3 (ω -3) fatty acid, meaning the last double bond (omega=last) is positioned 3 carbons from the methyl end (-CH ) of the chain: 3 • The example of linolenic acid above would be designated as (18:3 ω -3). “18:3” indicates that linolenic acid has 18 carbon atoms and 3 double bonds 23 Saturday, September 24, 2016 • ω -3 tells us the last double bond is 3 carbons from the methyl end of the molecule Essential fatty acids: • Our bodies can synthesize all of the fatty acids we need except for two: linoleic acid (18:2 ω-6) and lenolenic acid (18:3 ω-3). • Notice that linolenic acid is an omega-3 fatty acid, and linoleic acid is an omega-6 fatty acid. • They are called essential fatty acids because we must obtain these fatty acids from food. The RDA for essential fatty acids is 1-2% of total energy intake. Fortunately, linoleic acid and lenolenic acid are widespread in vegetable oils. Most people consume much more than the RDA, so essential fatty acid deficiencies are rare. • The essential fatty acids linoleic acid and linolenic acid can be converted to other fatty acids by elongation and desaturation reactions. For example, linoleic acid (18:2 ω-6) can be elongated and desaturated to form arachidonic acid (20:4 ω-6). Omega-3 fatty acids: •  Omega-3 fatty acids have received considerable media attention. Research suggests that these particular fatty acids have anti- inflammatory, antithrombotic, and vasodilatory properties. When they replace other fats in the diet, it also appears that ω-3 fatty 24 Saturday, September 24, 2016 acids may decrease circulating triglyceride levels. 
 •  As mentioned previously, lenolenic acid (18:3 ω-3) is one example of an omega-3 fatty acid. It is an essential FA found in walnuts, flaxseed, canola oil, and soybean oils. Triglycerides: • Triglyceride = a glycerol molecule esterfied to 3 fatty acids • Triglycerides are also commonly called “triacylglycerols” by biochemists. • Triglycerides may be solid or liquid at room temperature, depending on the degree of saturation among its fatty acids. • Oils = liquid triglycerides. •  Triglycerides can be hydrolyzed to glycerol and free fatty acids. •  Lipases are enzymes that catalyze such hydrolysis reactions. •  Triglycerides are the main storage form of energy in the body. Triglyceride molecules are stored in adipocytes (fat cells). • When the body needs fuel, triglycerides are hydrolyzed to glycerol and free fatty acids. Then fatty acids are oxidized to yield large amounts of energy. Trans fatty acids: Trans fatty acids are naturally present in very small amounts in animal foods. The vast majority of trans-fatty acids are produced by an industrial process called hydrogenation. 25 Saturday, September 24, 2016 Phospholipids (phosphoglycerides) • Phospholipids are another class of lipid molecule. Phospholipids are similar in structure to triglycerides except one of the three carbon atoms of the glycerol backbone is esterfied to phosphate rather than a third fatty acid. • Phospholipids are the main component of cell membranes. Sphingolipids • Sphingolipids are lipids that contain an aminoalcohol called sphingosine. Like phospholipids, sphingolipids are often part of cell membranes. • The brain and other tissues of the nervous system are rich in sphingolipids. Steroids: • Steroids are lipids that are structurally very different from triglycerides. Steroids have a characteristic structure of 3 six- member rings and 1 five- member ring fused together. Steroids • Cholesterol is the most abundant steroid in the human body. 26 Saturday, September 24, 2016 • Cholesterol is consumed in the diet and synthesized de novo in the liver from acetyl CoA. On average, ~1/3 of the cholesterol in one’s body comes from diet, and ~2/3 is synthesized endogenously. Cholesterol plays several important roles in the human body: • • Essential component of the plasma membrane of cells
 • Component of bile salts that are necessary to emulsify dietary lipids so that they can be digested and absorbed • • Precursor for vitamin D and other steroid hormones (e.g., sex hormones and adrenocorticoid hormones) Steroid hormones: • Lipid-soluble steroid hormones can cross the plasma membrane of cells to bind to receptors inside cells. • The steroid-receptor complex can then bind to specific regions of DNA (promoter regions) to either stimulate or inhibit gene transcription. Eicosanoids • Eicosanoids are a family of signaling molecules synthesized in the body from the 20-C unsaturated fatty acid arachidonic acid. 
 • Eicosanoids include thromboxanes, leukotrienes, and prostaglandins. 27


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