chapter 4: cell metabolism chapter 4: cell metabolism

Chapter 4: Cell Metabolism

Chapter 4: Cell Metabolism

Copyright © 2007 by Saunders, an imprint of Elsevier Inc.

All rights reserved.

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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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Name Function

DisaccharidesSucroseMaltoseLactose

Split into monosaccharidesSplit into monosaccharidesSplit into monosaccharides



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Name Function

PolysaccharidesStarchesGlycogenCellulose

Split into monosaccharidesDigested into monosaccharidesForms dietary fiber or roughage



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• 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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• 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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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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• 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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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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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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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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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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• 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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chapter 4: cell metabolism chapter 4: cell metabolism

Documents

imprint of elsevier

lipids fats contd

metabolism contd

roughagecarbohydrates

rnacarbohydrates contd

lipids fatslipids

use of carbohydrates

anaerobic catabolism