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INSTRUCTORS MANUAL for Advanced Nutrition and Human Metabolism 8th Edition by Sareen Gropper, Jack Smith & Timothy Carr Complete Elaborated & Latest . ALL Chapters[114]Included & Updated

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

Instructor Manual Gropper/Smith/Carr, Advanced Nutrition and Human Metabolism, c2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

Table of Contents Purpose and Perspective of the Chapter..................................................................................... 2 Chapter Objectives ........................................................................................................................ 2 Chapter Outline ............................................................................................................................. 2 Discussion Questions .................................................................................................................... 9 Activities and Assignments ......................................................................................................... 11 Additional Resources................................................................................................................... 14 Internet Resources .................................................................................................................................. 14 Appendix ...................................................................................................................................... 15 Standard Writing Rubric .......................................................................................................................... 15 Standard Discussion Rubric ..................................................................................................................... 16

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

Purpose and Perspective of the Chapter This chapter introduces the basic functions of the human cell to serve as background as students proceed to learn about nutrition and metabolism within the human body.

Chapter Objectives The following objectives are addressed in this chapter: 1.1

Identify cellular components and their functions.

1.2

Describe the roles of cell receptors and enzymes.

1.3

Explain the mechanisms by which enzymatic reactions are regulated.

1.4

Discuss the need for and pathways involved in apoptosis.

1.5

Describe how energy is released and utilized in chemical reactions.

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Chapter Outline I.

Introduction 1. This chapter provides a brief review of the basics of a cell, including cellular components, biological energy, and an overview of a cell’s natural life span. 2. Key Terms a. Cells—basic living, structural, and functional units of the human body b. Eukaryotic cells—multicellular organisms c. Prokaryotic cells—primitive cells d. Plasma membrane—sheetlike structure that encapsulates and surrounds the cell, allowing it to exist as a distinct unit 3. Figures and Tables a. Figure 1.1—three-dimensional depiction of a typical mammalian liver cell II. Components of Cells A. Plasma Membrane 1. Sheetlike structure that encapsulates and surrounds the cell. It is asymmetrical and considered to be a fluid structure 2. Key Terms a. Hydrophobic—molecule or part of molecule that repels water but has strong affinity for nonpolar substances b. Receptors—macromolecules that bind a signal molecule with a high degree of specificity that triggers intracellular events

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

c. Enzymes—protein catalysts that increase the rate of a chemical reaction in the body 3. Figures and tables a. Figure 1.2—lipid bilayer structure of biological membranes b. Figure 1.3—fluid model of cell membrane. Lipids and proteins are mobile and can move laterally in the membrane B. Cytosol and Cytoskeleton 1. The cytoplasm includes a. Cytosol—a gel-like liquid inside the plasma membrane but not in the nucleus b. Cytoskeleton—made up of microtubules, intermediate filaments, and microfilaments 2. Organelles Key Terms a. Microtubules—hollow, cylindrical cytoskeletal structures composed of the protein tubulin that act to support the cell structure b. Intermediate filaments—strong, ropelike cytoskeletal fibers that are made of protein and that function to provide mechanical stability to cells c. Microfilaments—solid cytoskeletal structures made of a double-helix polymer of the protein actin that play a role in cell motility 3. Microtubules, intermediate filaments, and microfilaments—make up the cytoskeleton 4. Structural arrangement of the cell influences metabolic pathways a. Hexose monophosphate shunt—pentose phosphate pathway 5. Figures and tables a. Figure 1.4—the cytoskeleton provides a structure for cell organelles, microvilli, and large molecules C. Mitochondrion 1. Cellular organelle that is the site of energy production by oxidative phosphorylation and the site of tricarboxylic acid cycle 2. Key terms a. Mitochondria—primary sites of oxygen use and ATP production in cells b. Oxidative phosphorylation—pathway in the mitochondria that makes ATP from ADP and Pi c. Electron transport chain—sequential transfer of electrons from reduced coenzymes to oxygen that is coupled with ATP formation and occurs within the mitochondria 3. Mitochondrial membrane—a double membrane that surrounds the mitochondrial matrix; the inner membrane is less permeable than the porous outer membrane 4. Mitochondrial matrix—the interior space in which metabolic enzyme systems catalyze reactions of the tricarboxylic acid and fatty acid oxidation 5. Figures and tables

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

a. Figure 1.5—the mitochondrion b. Figure 1.6—overview of a cross section of a mitochondrion D. Nucleus 1. Largest organelle within the cell, regulating most cellular activities 2. Key terms a. Nuclear envelope—composed of an inner and an outer membrane; surrounds the cell nucleus b. Nucleolus—region of the nucleus containing condensed chromatin and sites for synthesizing ribosomal RNA c. Genes—section of chromosomal DNA that codes for a single protein d. Genome—sum of all the chromosomal genes of a cell e. Nucleotides—phosphate esters of the 5ʹ-phosphate of a purine or pyrimidine in N-glycosidic linkage with ribose or deoxyribose; occurs in nucleic acids f. Complementary base pairing—pairing of nucleotide bases in two strands ofnucleic acids; A pairs with T or U, while G pairs with C g. Replication—synthesis of a daughter duplex DNA molecule identical to the parental duplex DNA h. Transcription factors—auxiliary proteins that bind to specific sites in the DNA and alter the transcription of nearby genes i. Sense strand—the strand of DNA that serves as a template for mRNA j. Introns—noncoding regions of a gene k. Exons—coding regions of a gene l. Anticodons—three-base sequences of nucleotides within transfer RNA molecules m. Elongation—extension of the polypeptide chain of the protein product during protein synthesis n. Signal transduction—cascade of events that leads to translocation of a transcription factor into the nucleus o. Translocation—movement of a transcription factor into the nucleus, where it can bind to DNA p. MicroRNAs—small noncoding RNAs that silence gene expression by binding to mRNA to inhibit its translation and/or promote its degradation 3. Nucleic acids—macromolecules of nucleotides; consist of a nitrogenous core, a pentose sugar, and a phosphate 4. Cell replication—synthesis of daughter DNA identical to the parental DNA 5. Transcription—taking genetic information in a single strand of DNA and making a specific sequence of bases in a messenger RNA chain 6. Translation—process by which genetic information in an mRNA molecule is turned into the sequence of amino acids in the protein 7. Control of gene expression—controlled through transcription, processing-level control mechanisms determine the path by which mRNA is translated into

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

polypeptide, and translation-level control mechanisms determine which mRNA is translated 8. Figures and tables a. Figure 1.7—steps of protein synthesis b. Figure 1.8—DNA replication E. Endoplasmic Reticulum and Golgi Apparatus 1. The organelles function together to create a mechanism for communication from the innermost part of the cell to its exterior 2. Key terms a. Endoplasmic reticulum—network of membranous channels pervading the cytosol and providing continuity between the nuclear envelope, the Golgi apparatus, and the plasma membrane b. Sarcoplasmic reticulum—smooth endoplasmic reticulum that is found in muscle cells and is the site of the calcium pump c. Cytochromes—heme-containing proteins that serve as electron carriers, such as in the P450 system d. Oxidation—enzymatic reaction in which oxygen is added to, or hydrogen and its electrons are removed from the reactant e. Lipophilic—attraction to lipids and thus repelled by water f. Hydrophilic—attraction to water and other polar substances g. Golgi apparatus—the part of the cell responsible for modifying macromolecules synthesized in the endoplasmic reticulum and packaging them to be transported to the cell surface or cytosol F. Lysosomes and Peroxisomes 1. Aid in cell’s digestion and oxidative catabolic reactions 2. Key terms a. Lysosomes—cell organelles that contain digestive enzymes b. Peroxisomes—cell organelles containing enzymes that perform oxidative catabolic reactions c. Catabolism—process by which organic molecules are broken down III. Selected Cellular Proteins A. Receptors 1. Highly specific proteins located in the plasma membrane and act as recognition markers 2. Key terms a. Ligands—small molecules or minerals that bind to a receptor on the plasma membrane b. Protein kinases—enzymes that add a phosphate group to an enzyme, generally activating the enzyme 3. Receptors that generate internal chemical signals—an internal chemical signal is generated following interaction between some receptors and ligands

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

4. Receptors that function as ion channels—in some cases, the binding of the ligand to its receptor causes a voltage change, which then becomes the signal for a cellular response 5. Receptors that internalize stimuli—a stimulus is internalized through a stimulus 6. Receptor’s role in homeostasis—receptors that respond to changes in the external conditions 7. Figures and tables a. Figure 1.9—example of an internal chemical signal by a second messenger b. Figure 1.10—internalization of a stimulus into a cell via its receptor B. Catalytic Proteins (Enzymes) 1. Enzymes catalyze reactions, taking part in reactions, but they are not part of the final product of that reaction 2. Key terms a. Oxidoreductases—enzymes that catalyze reactions in which one compound is oxidized and another is reduced b. Transferases—enzymes that catalyze reactions not involving oxidation and reduction in which a functional group is transferred from one substrate to another c. Hydrolases—enzymes that catalyze cleavage of bonds between carbon atoms and some other kind of atom by the addition of water d. Lyases—enzymes that catalyze cleavage of carbon–carbon, carbon–sulfur, and certain carbon–nitrogen bonds without hydrolysis or oxidation-reduction e. Isomerases—enzymes that catalyze the interconversion of optical or geometric isomers f. Ligases—enzymes that catalyze the formation of bonds between carbon and other atoms g. Ischemia—deficiency of blood in a tissue h. Oncogenes—mutated genes capable of causing a normal cell to convert to a cancerous cell 3. Reversibility—the ability of an enzyme to catalyze a reaction in both directions 4. Regulation—control of anabolic and catabolic reactions to maintain balance a. Covalent modification—enzyme is inactive until it is posttranslationallymodified (a change is made after the protein was synthesized). b. Allosteric enzyme modulation—a secondary regulatory mechanism present in certain enzymes called allosteric enzymes. These enzymes possess another specific site besides the catalytic site c. Induction—creates changes in the concentration of certain inducible enzymes by increasing enzyme synthesis 5. Examples of enzyme types—enzymes are classified by the type of reaction they influence (see a–f under Key Terms) 6. Clinical applications of cellular enzymes—enzymes are synthesized

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

intracellularly, and most function within the cell in which they are formed. The concentration of some enzymes in the serum is used clinically to diagnose medical disorders. In order to be clinically useful, enzymes must a. Have high degree of organ or tissue specificity b. Have a steep concentration gradient of enzyme activity between the interior and exterior of cells c. Function in the cytosol of the cell so that it leaks out when cell is damaged d. Be stable for a reasonable time period in the vascular compartment IV. Apoptosis 1. Programmed cell death 2. Key terms a. Apoptosis—programmed cell death b. Caspases—family of cysteine proteases involved in the degradative events during apoptosis c. Tumor necrosis factor—a cytokine released by immune cells and mast cells that causes destruction of tumors and migration of neutrophils toward the site of bacterial infections d. Oncosis—a prelethal pathway accompanied by cellular swelling, organelle swelling, and increased membrane permeability that lead to cell death e. Motility—movement V. Biological Energy A. Energy Release and Consumption in Chemical Reactions 1. Energy is derived from macronutrients 2. Key terms a. Macronutrients—dietary nutrients that supply energy, including fats, carbohydrates, and proteins 3. Figures and tables a. Figure 1.11—adenosine triphosphate b. Figure 1.12—a comparison of the simple combustion and the metabolic oxidation of the fatty acid palmitate B. Units and Expressions of Energy 1. Units of energy—calories are the unit of energy used throughout this text. Kcal is used to represent 1,000 calories, as would be present in food. 2. Key terms a. Free energy—the potential energy inherent in the chemical bonds of nutrients b. Exothermic—a reaction in which the reactants have more free energy than the products; it therefore gives off energy as heat c. Endothermic—a reaction in which the products have more free energy than the reactants; it therefore requires energy d. Transition state—energy level at which reactant molecules have been

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

activated and can undergo an exothermic reaction e. Activation energy—energy introduced into the reactant molecules to activate them to the transition state so that an exothermic reaction can take place 3. Free energy—potential energy inherent in the chemical bonds of nutrients that is released if the molecules undergo oxidation 4. Exothermic and endothermic reactions—reactions either requiring energy or releasing energy 5. Activation energy—energy required for a reaction to occur. Exothermic reactions are favored since they do not require external energy input 6. Cellular energy—how the cell derives its energy from a series of chemical reactions 7. Reversibility of chemical reactions—most cellular reactions are reversible, meaning an enzyme can catalyze in both directions 8. Standard free energy change—a temperature of 25°C (298 K), a pressure of 1.0 atm, and the presence of both the reactants and the products at their standard concentrations, namely 1.0 mol/L 9. Equilibrium constant and standard free energy change—the equilibrium constant of a reaction determines the sign and magnitude of the standard free energy change 10. Standard pH—7.0 is the adopted standard pH value, near neutral for biochemical reactions 11. Nonstandard physiological conditions—physiological standard conditions do not often exist, which may explain why reactions proceed when the conditions are not standard 12. Figures and tables a. Figure 1.13—the uphill–downhill concept illustrating energy-releasing and energy-demanding processes b. Figure 1.14—example of a shift in the equilibrium by changing from standard conditions to physiological conditions C. The Role of High-Energy Phosphate in Energy Storage 1. ATP can be used as a universal source of energy through the hydrolysis of the phosphate bonds 2. Figures and tables a. Figure 1.15—examples of very high-energy phosphate compounds b. Figure 1.16—an illustration of how ATP is generated from the coupling of ADP and phosphate through the oxidative catabolism of nutrients and in turn, is used for energy-requiring processes D. Coupled Reactions in the Transfer of Energy 1. Reactions that require energy and reactions that yield energy 2. Figures and tables a. Figure 1.17—examples of high-energy phosphate bonds being transferred

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

b. Figure 1.18—exothermic reactions E. Reduction Potentials 1. Ability of a compound to be reduced by accepting an electron or electrons 2. Key terms a. Standard reduction potential—tendency of a molecule to donate or receive electrons b. Hydrogen atoms—electrically neutral element of hydrogen containing one proton and one electron VI. Summary A. Plasma Membrane 1. Ability to protect the cell while adjusting to the environment B. Communication of the Cell 1. Cell’s ability to use the cytosol, microtrabecular network, and the endoplasmic reticulum and Golgi apparatus to communicate between the nucleus and plasma membrane C. Division of Labor among Cell Components 1. Each organelle has a unique function, with little overlap D. Nucleus 1. Ability to ensure all needed proteins are synthesized E. Apoptosis 1. Programmed cell death F. External Needs of the Cell 1. Energy from macronutrients 2. Nutrients that serve as building blocks 3. Vitamins, minerals and water as regulatory nutrients [return to top]

Discussion Questions You can assign these questions several ways: in a discussion forum in your LMS, as wholeclass discussions in person, or as a partner or group activity in class. 1. Discussion: When the Cell Goes Awry a. Some individuals have high levels of cholesterol in their blood, hypercholesterolemia, that is associated with coronary heart disease. Let’s consider some differences in the cells of different people that could contribute to higher or lower levels of blood cholesterol. One type of receptor on the membrane of liver cells is the LDL receptor. The ligand for that receptor is circulating LDL. b. What might happen if someone’s cells were not able to make LDL receptors? i. Answer: If there were no LDL receptors, the ligand LDL could not bind to a receptor on the plasma membrane of the cell. It would have no

2022, 9780357449813; Chapter 1: The Cell: A Microcosm of Life

way to enter cells, causing the LDL-associated cholesterol in the blood to become very high, which can eventually lead to a heart attack. c. Another genetic difference is a patient who does not synthesize the protein PCSK9. Normally, PCSK9 binds to LDL receptors, preventing LDL from binding. d. For patients who do not make PCSK9, what might their blood cholesterol levels be? i. Answer: Their blood cholesterol levels would be low because they would have many LDL receptors available to take LDL cholesterol from the blood into cells. 2. Discussion: Regulation of Enzyme Activity a. Enzyme activity is regulated by three major mechanisms. b. Name each of the three mechanisms, and explain how each one works. i. Answer: 1. In covalent modification, after the enzyme has been synthesized, a post-translational change can occur, likely adding or removing a phosphate group. 2. In allosteric enzyme modulation, the enzyme has an allosteric site in addition to the catalytic site. Another compound (a modulator) can bind to the allosteric site, changing the activity of the enzyme (either increasing or decreasing depending on the specific enzyme and modulator). 3. In enzyme induction, the concentration of the available enzyme is increased by increased synthesis of the protein, depending upon cellular conditions. 3. Discussion: Oxidation and Reduction a. What serves as the electron acceptor and donor throughout the oxidation and reduction of glucose? i. Answer: NADH; when NAD+, it is able to accept the hydrogen; when NADH, it is able to donate the hydrogen. 4. Discussion: Genetic Differences in the ER—You may pose this question when discussing the Perspectives section of this chapter. a. The endoplasmic reticulum has multiple roles, including translation and protein regulation. What are some disorders that the endoplasmic reticulum plays a role in? i. Answer: Cystic fibrosis, type 1 diabetes, neonatal diabetes. [return to top]