Chapter 4: Cell Metabolism
Jan 21, 2016
Chapter 4: Cell Metabolism
Chapter 4: Cell Metabolism
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Lesson 4.1 ObjectivesLesson 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.
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MetabolismMetabolism
• 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
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Metabolism (cont’d.)Metabolism (cont’d.)
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CarbohydratesCarbohydrates
• 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
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Carbohydrates (cont’d.)Carbohydrates (cont’d.)
Name Function
MonosaccharidesGlucoseFructoseGalactoseDeoxyriboseRibose
Most important energy sourceConverted to glucoseConverted to glucoseSugar in DNASugar in RNA
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Carbohydrates (cont’d.)Carbohydrates (cont’d.)
Name Function
DisaccharidesSucroseMaltoseLactose
Split into monosaccharidesSplit into monosaccharidesSplit into monosaccharides
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Carbohydrates (cont’d.)Carbohydrates (cont’d.)
Name Function
PolysaccharidesStarchesGlycogenCellulose
Split into monosaccharidesDigested into monosaccharidesForms dietary fiber or roughage
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Carbohydrates (cont’d.)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
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Carbohydrates (cont’d.)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
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Carbohydrates (cont’d.)Carbohydrates (cont’d.)
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Lipids (Fats)Lipids (Fats)
• Lipids: organic compounds commonly calledfats and oils
• Most common:– Triglycerides– Phospholipids– Steroids
• Other relatives of lipids:– Lipoid substances
• Lipids: organic compounds commonly calledfats and oils
• Most common:– Triglycerides– Phospholipids– Steroids
• Other relatives of lipids:– Lipoid substances
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Lipids (Fats) (cont’d.)Lipids (Fats) (cont’d.)
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Lipids (Fats) (cont’d.)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
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Lipids (Fats) (cont’d.)Lipids (Fats) (cont’d.)
Name Function
Triglycerides In adipose tissue; protect and insulate body organs; major source of stored energy
Phospholipids Found in cell membranes
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Lipids (Fats) (cont’d.)Lipids (Fats) (cont’d.)
Name Function
Steroids:
Cholesterol Used in synthesis of steroids
Bile salts Assist in digestion of fats
Vitamin D Synthesized in skin on exposure to ultraviolet radiation; contributes to calcium and phosphate homeostasis
Hormones Adrenal cortical hormones are necessary for life and affect every body system; ovaries and testes secrete sex hormones
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Lipids (Fats) (cont’d.)Lipids (Fats) (cont’d.)
Name Function
Lipoid substances:
Fat-soluble vitamins
Various functions
Prostaglandins Found in cell membranes; affect smooth muscle contraction
Lipoproteins Help transport fatty acids; HDL “good”; LDL “bad”
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ProteinsProteins
• 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
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Amino AcidsAmino 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
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Amino Acids (cont’d.)Amino Acids (cont’d.)
• Common amino acids:Alanine Glycine Proline
Arginine Histidine* Serine
Asparagine Isoleucine* Threonine*
Aspartic acid Leucine* Tryptophan*
Cysteine Lysine* Tyrosine
Glutamic acid Methionine* Valine*
Glutamine Phenylalanine*
*Essential amino acids
• Common amino acids:Alanine Glycine Proline
Arginine Histidine* Serine
Asparagine Isoleucine* Threonine*
Aspartic acid Leucine* Tryptophan*
Cysteine Lysine* Tyrosine
Glutamic acid Methionine* Valine*
Glutamine Phenylalanine*
*Essential amino acids
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Types of ProteinTypes 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
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Types of Protein (cont’d.)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
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Uses of ProteinsUses 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)
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Uses of Proteins (cont’d.)Uses of Proteins (cont’d.)
• Nitrogen: waste product of amino acid breakdown
– Most nitrogen is recycled for new amino acids
– Extra nitrogen forms ammonia (NH3)
– Liver pulls NH3 from blood and converts it to urea
– Kidneys excrete ureain urine
• Nitrogen: waste product of amino acid breakdown
– Most nitrogen is recycled for new amino acids
– Extra nitrogen forms ammonia (NH3)
– Liver pulls NH3 from blood and converts it to urea
– Kidneys excrete ureain urine
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Lesson 4.2 ObjectivesLesson 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.
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Protein Synthesis and DNAProtein 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
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Protein Synthesis and DNA (cont’d.)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
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Protein Synthesis and DNA (cont’d.)Protein Synthesis and DNA (cont’d.)
DNA RNA
Sugar Deoxyribose
Ribose
Base AdenineGuanineCytosineThymine
AdenineGuanineCytosineUracil
Strands Double (2) Single (1)
• Comparison of DNA and RNA structures:• Comparison of DNA and RNA structures:
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Protein Synthesis and DNA (cont’d.)Protein Synthesis and DNA (cont’d.)
• Five steps in protein synthesis:1. Strands of DNA in the nucleus separate; DNA
strand is copied onto mRNA2. 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 form5. 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 mRNA2. 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 form5. Protein chain terminates when all amino acids
have been assembled in sequence
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Protein Synthesis and DNA (cont’d.)Protein Synthesis and DNA (cont’d.)