Chapter 4: Cell Metabolism Chapter 4: Cell Metabolism

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2 Lesson 4.1 Objectives Define metabolism, anabolism, and catabolism. Explain the use of carbohydrates, proteins, and fats in the body. Differentiate between the anaerobic and aerobic metabolism of carbohydrates. Define metabolism, anabolism, and catabolism. Explain the use of carbohydrates, proteins, and fats in the body. Differentiate between the anaerobic and aerobic metabolism of carbohydrates.

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3 Metabolism Metabolism: the series of chemical reactions necessary for the use of raw material –Anabolism: reactions that build larger, more complex substances from simpler substances –Catabolism: reactions that break down larger, more complex substances into simpler substances Metabolism: the series of chemical reactions necessary for the use of raw material –Anabolism: reactions that build larger, more complex substances from simpler substances –Catabolism: reactions that break down larger, more complex substances into simpler substances

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4 Metabolism (cont’d.)

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5 Carbohydrates Carbohydrates: organic compounds composed of carbon (C), hydrogen (H), and oxygen (O) –Monosaccharides: single-sugar compounds –Disaccharides: double-sugars –Polysaccharides: many-sugar compounds Carbohydrates: organic compounds composed of carbon (C), hydrogen (H), and oxygen (O) –Monosaccharides: single-sugar compounds –Disaccharides: double-sugars –Polysaccharides: many-sugar compounds

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6 Carbohydrates (cont’d.) NameFunction Monosaccharides Glucose Fructose Galactose Deoxyribose Ribose Most important energy source Converted to glucose Sugar in DNA Sugar in RNA

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7 Carbohydrates (cont’d.) NameFunction Disaccharides Sucrose Maltose Lactose Split into monosaccharides

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8 Carbohydrates (cont’d.) NameFunction Polysaccharides Starches Glycogen Cellulose Split into monosaccharides Digested into monosaccharides Forms dietary fiber or roughage

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9 Carbohydrates (cont’d.) Uses of glucose: –Burned immediately for fuel –Stored as glycogen and burned as fuel later –Stored as fat and burned as fuel later Uses of glucose: –Burned immediately for fuel –Stored as glycogen and burned as fuel later –Stored as fat and burned as fuel later

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10 Carbohydrates (cont’d.) Breakdown of glucose: –Anaerobic catabolism: oxygen absent Glycolysis: occurs in the cytoplasm; chemical reactions break down glucose into pyruvic acid and then lactic acid –Aerobic catabolism: oxygen present Glucose is completely broken down into pyruvic acid and then down into carbon dioxide, water, and ATP Breakdown of glucose: –Anaerobic catabolism: oxygen absent Glycolysis: occurs in the cytoplasm; chemical reactions break down glucose into pyruvic acid and then lactic acid –Aerobic catabolism: oxygen present Glucose is completely broken down into pyruvic acid and then down into carbon dioxide, water, and ATP

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11 Carbohydrates (cont’d.)

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12 Lipids (Fats) Lipids: organic compounds commonly called fats and oils Most common: –Triglycerides –Phospholipids –Steroids Other relatives of lipids: –Lipoid substances Lipids: organic compounds commonly called fats and oils Most common: –Triglycerides –Phospholipids –Steroids Other relatives of lipids: –Lipoid substances

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13 Lipids (Fats) (cont’d.)

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14 Lipids (Fats) (cont’d.) Uses of lipids: –Energy source –Component of cell membranes and myelin sheath –Synthesis of steroids –Long-term energy storage Uses of lipids: –Energy source –Component of cell membranes and myelin sheath –Synthesis of steroids –Long-term energy storage

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15 Lipids (Fats) (cont’d.) NameFunction TriglyceridesIn adipose tissue; protect and insulate body organs; major source of stored energy PhospholipidsFound in cell membranes

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16 Lipids (Fats) (cont’d.) NameFunction Steroids: CholesterolUsed in synthesis of steroids Bile saltsAssist in digestion of fats Vitamin DSynthesized in skin on exposure to ultraviolet radiation; contributes to calcium and phosphate homeostasis HormonesAdrenal cortical hormones are necessary for life and affect every body system; ovaries and testes secrete sex hormones

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17 Lipids (Fats) (cont’d.) NameFunction Lipoid substances: Fat-soluble vitamins Various functions ProstaglandinsFound in cell membranes; affect smooth muscle contraction LipoproteinsHelp transport fatty acids; HDL “good”; LDL “bad”

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18 Proteins Most abundant organic matter in the body Participate in every body function –Enzymes are proteins –Most hormones are proteins –Hemoglobin is a protein –Contractile muscle proteins enable movement Most abundant organic matter in the body Participate in every body function –Enzymes are proteins –Most hormones are proteins –Hemoglobin is a protein –Contractile muscle proteins enable movement

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19 Amino Acids Amino acids: building blocks of protein –Essential amino acids: cannot be synthesized by the body –Nonessential amino acids: can be synthesized by the liver Amino acids: building blocks of protein –Essential amino acids: cannot be synthesized by the body –Nonessential amino acids: can be synthesized by the liver

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20 Amino Acids (cont’d.) Common amino acids: AlanineGlycineProline ArginineHistidine*Serine AsparagineIsoleucine*Threonine* Aspartic acidLeucine*Tryptophan* CysteineLysine*Tyrosine Glutamic acidMethionine*Valine* GlutaminePhenylalanine* *Essential amino acids Common amino acids: AlanineGlycineProline ArginineHistidine*Serine AsparagineIsoleucine*Threonine* Aspartic acidLeucine*Tryptophan* CysteineLysine*Tyrosine Glutamic acidMethionine*Valine* GlutaminePhenylalanine* *Essential amino acids

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21 Types of Protein Structural proteins: –Components of cell membranes: determine pore size; allow hormones to “recognize” cell –Collagen: structural component of muscle and tendons –Keratin: part of skin and hair Peptide hormones: many hormones are proteins and have widespread effects on many organ systems Structural proteins: –Components of cell membranes: determine pore size; allow hormones to “recognize” cell –Collagen: structural component of muscle and tendons –Keratin: part of skin and hair Peptide hormones: many hormones are proteins and have widespread effects on many organ systems

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22 Types of Protein (cont’d.) Hemoglobin: transport of oxygen Antibodies: protect body from disease-causing microorganisms Plasma proteins: blood clotting; fluid balance Muscle proteins: enable muscle to contract Enzymes: regulate the rates of chemical reactions Hemoglobin: transport of oxygen Antibodies: protect body from disease-causing microorganisms Plasma proteins: blood clotting; fluid balance Muscle proteins: enable muscle to contract Enzymes: regulate the rates of chemical reactions

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23 Uses of Proteins Three uses of proteins: –Synthesis of hormones, enzymes, antibodies, plasma and muscle proteins, hemoglobin, and most cell membranes –If needed, can be broken down as source of energy for ATP production –If needed, can be broken down and converted to glucose (gluconeogenesis) Three uses of proteins: –Synthesis of hormones, enzymes, antibodies, plasma and muscle proteins, hemoglobin, and most cell membranes –If needed, can be broken down as source of energy for ATP production –If needed, can be broken down and converted to glucose (gluconeogenesis)

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24 Uses of Proteins (cont’d.) Nitrogen: waste product of amino acid breakdown –Most nitrogen is recycled for new amino acids –Extra nitrogen forms ammonia (NH 3 ) –Liver pulls NH 3 from blood and converts it to urea –Kidneys excrete urea in urine Nitrogen: waste product of amino acid breakdown –Most nitrogen is recycled for new amino acids –Extra nitrogen forms ammonia (NH 3 ) –Liver pulls NH 3 from blood and converts it to urea –Kidneys excrete urea in urine

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25 Lesson 4.2 Objectives Describe the structure of a nucleotide. Describe the roles of DNA and RNA in protein synthesis. Describe protein synthesis. Describe the structure of a nucleotide. Describe the roles of DNA and RNA in protein synthesis. Describe protein synthesis.

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 26 Protein Synthesis and DNA Nucleotide: three parts composed of a sugar, a phosphate group, and a base Nucleic acids: composed of nucleotides –DNA: two strands of nucleotides arranged in a twisted ladder formation; stores genetic code –RNA: resembles the structure of DNA; copies and delivers code for protein synthesis Nucleotide: three parts composed of a sugar, a phosphate group, and a base Nucleic acids: composed of nucleotides –DNA: two strands of nucleotides arranged in a twisted ladder formation; stores genetic code –RNA: resembles the structure of DNA; copies and delivers code for protein synthesis

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27 Protein Synthesis and DNA (cont’d.) DNA structures: –Base-pairing: how strands are linked together –Base-sequencing: order of three- base amino acid sequences along a single strand –Genetic information stored in sequences of bases DNA structures: –Base-pairing: how strands are linked together –Base-sequencing: order of three- base amino acid sequences along a single strand –Genetic information stored in sequences of bases

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 28 Protein Synthesis and DNA (cont’d.) DNARNA SugarDeoxyriboseRibose BaseAdenine Guanine Cytosine Thymine Adenine Guanine Cytosine Uracil StrandsDouble (2)Single (1) Comparison of DNA and RNA structures:

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 29 Protein Synthesis and DNA (cont’d.) Five steps in protein synthesis: 1. Strands of DNA in the nucleus separate; DNA strand is copied onto mRNA 2. mRNA leaves nucleus; travels to ribosomes 3. Code determines which amino acids attach 4. Amino acids are lined up in proper sequence along ribosome; peptide bonds form 5. Protein chain terminates when all amino acids have been assembled in sequence Five steps in protein synthesis: 1. Strands of DNA in the nucleus separate; DNA strand is copied onto mRNA 2. mRNA leaves nucleus; travels to ribosomes 3. Code determines which amino acids attach 4. Amino acids are lined up in proper sequence along ribosome; peptide bonds form 5. Protein chain terminates when all amino acids have been assembled in sequence

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30 Protein Synthesis and DNA (cont’d.)