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Chapter 4 Energy and Cellular Metabolism. About this Chapter Energy in biological systems Chemical reactions Enzymes Metabolism ATP production Synthetic.

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Presentation on theme: "Chapter 4 Energy and Cellular Metabolism. About this Chapter Energy in biological systems Chemical reactions Enzymes Metabolism ATP production Synthetic."— Presentation transcript:

1 Chapter 4 Energy and Cellular Metabolism

2 About this Chapter Energy in biological systems Chemical reactions Enzymes Metabolism ATP production Synthetic pathways

3 Figure 4-1 Energy: Biological Systems Energy transfer in the environment Photosynthesis takes place in plant cells, yielding: Radiant energy Energy lost to environment Heat energy Energy stored in biomolecules Sun Respiration takes place in human cells, yielding: Energy for work Energy stored in biomolecules H2OH2O + + Transfer of radiant or heat energy Transfer of energy in chemical bonds KEY CO 2 CO 2 + H2OH2O N2N2

4 Energy: Capacity to Do Work Chemical work Making and breaking of chemical bonds Transport work Moving ions, molecules, and larger particles Can create concentration gradients Mechanical work Used for movement

5 Kinetic and Potential Energy Figure 4-2

6 Thermodynamic Energy First law of Thermodynamics Total amount of energy in the universe is constant Second law of Thermodynamics Processes move from state of order to disorder

7 Figure 4-3 Chemical Reactions: Overview Activation energy is the energy that must be put into reactants before a reaction can proceed A + B  C + D

8 Chemical Reactions: Exergonic and endergonic Figure 4-4 KEY Activation energy Net free energy change C+D A+B G+H Net free energy change E+F Reactants Activation of reaction Reaction process Products (a) Exergonic reactions (b) Endergonic reactions

9 Chemical Reactions: Coupling Figure 4-5

10 Enzymes: Overview Isozymes Catalyze same reaction, but under different conditions May be activated, inactivated, or modulated Coenzymes  vitamins Chemical modulators  temperature and pH

11 Enzymes: Lower activation energy Figure 4-6 KEY Net free energy change Activation energy C+D Reactants Activation of reaction Reaction process Products A+B

12 Enzymes: Law of Mass Action Figure 4-9a

13 Enzymes: Law of Mass Action Figure 4-9b

14 Enzymes: Types of Reactions Table 4-4

15 Figure 4-10 Metabolism: Overview A group of metabolic pathways resembles a road map

16 Metabolism: Cell Regulation 1.Controlling enzyme concentrations 2.Producing allosteric and covalent modulators 3.Using different enzymes for reversible reactions 4.Isolating enzymes within organelles 5.Maintaining optimum ratio of ATP to ADP

17 Metabolism: Cell Regulation Figure 4-11 Feedback inhibition enzyme 3enzyme 2enzyme 1

18 Metabolism: Cell Regulation Figure 4-12 H2OH2O CO 2 PO 4 (a) Carbonic acid Glucose 6-phosphate Glucose ++ Glucose 6-phosphate (c)(b) carbonic anhydrase carbonic anhydrase glucose 6- phosphatase hexokinase +

19 Figure 4-13 ATP Production: Overview Overview of aerobic pathways for ATP production Glycerol Fatty acids Amino acids Amino acids Amino acids CO 2 ADP Cytosol Mitochondrion ATP ADP GLYCOLYSISGLYCOLYSIS Pyruvate Acetyl CoA Glucose H2OH2OO2O2 High-energy electrons and H + ELECTRON TRANSPORT SYSTEM ATP ADP CITRIC ACID CYCLE ATP High-energy electrons Acetyl CoA Citric acid cycle

20 Figure 4-14 ATP Production: Glycolysis Glucose + 2 NAD ADP + P  2 Pyruvate + 2 ATP + 2 NADH + 2 H H 2 0 Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Dihydroxyacetone phosphate ATP ADP ATP ADP This section happens twice for each glucose molecule that begins glycolysis = Carbon = Oxygen = Phosphate group (side groups not shown) Glyceraldehyde 3-phosphate 1, 3-Bisphosphoglycerate 3-Phosphoglycerate 2-Phosphoglycerate Phosphoenol pyruvate Pyruvate ADP Glucose H2OH2O NADH KEY ATP NAD+ ADP

21 Figure 4-15 ATP Production: Pyruvate Metabolism Pyruvate can be converted into lactate or acetyl CoA Pyruvate Acetyl CoA H and –OH not shown = Carbon = Oxygen = Coenzyme A KEY Acetyl CoA Acyl unit CoA Cytosol Mitochondrial matrix Pyruvate Lactate NAD + CO 2 NADH NAD + AnaerobicAerobic CITRIC ACID CYCLE CoA

22 Figure 4-16 ATP Production: Citric Acid Cycle Acetyl CoA enters the citric acid cycle producing 3 NADH, 1 FADH 2, and 1 ATP KEY High-energy electrons Acetyl CoA Citric acid cycle Fumarate (4C) Malate (4C) Oxaloacetate (4C) H2OH2O Side groups not shown FADH 2 NADH NAD + Acetyl CoA CoA = Carbon = Oxygen = Coenzyme A Citrate (6C)  Ketoglutarate (5C) Succinyl CoA (4C) Succinate (4C) ATP CO 2 NADH FAD NAD + ADP CITRIC ACID CYCLE CoA GDP + P i GTP CoA NAD + Isocitrate (6C) CoA

23 ATP Production: Electron Transport Figure 4-17 H+H+ H+H+ H+H+ H+H+ Mitochondrial matrix Matrix pool of H + 4e – e–e– Inner mitochondrial membrane ADP + P i CITRIC ACID CYCLE High-energy electrons O2O2 + 2 H 2 O ATP H+H+ H+H+ Cytosol Outer mitochondrial membrane High-energy electrons from glycolysis H+H+ Intermembrane space Energy released during metabolism is captured by high-energy electrons carried by NADH and FADH 2. Energy from high-energy electrons moving along the electron transport system pumps H + from the matrix into the intermembrane space. Electrons at the end of the electron transport system are back to their normal energy state. They combine with H + and oxygen to form water. Potential energy captured in the H + concentration gradient is converted to kinetic energy when H + ions pass through the ATP synthase. Some of the kinetic energy is captured as ATP ATP synthase ELECTRON TRANSPORT SYSTEM

24 ATP Production: Electron Transport Figure 4-17, step 1 Mitochondrial matrix e–e– Inner mitochondrial membrane CITRIC ACID CYCLE High-energy electrons Cytosol Outer mitochondrial membrane High-energy electrons from glycolysis Intermembrane space Energy released during metabolism is captured by high-energy electrons carried by NADH and FADH ELECTRON TRANSPORT SYSTEM

25 ATP Production: Electron Transport Figure 4-17, steps 1–2 H+H+ H+H+ H+H+ Mitochondrial matrix e–e– e–e– Inner mitochondrial membrane CITRIC ACID CYCLE High-energy electrons H+H+ H+H+ Cytosol Outer mitochondrial membrane High-energy electrons from glycolysis H+H+ Intermembrane space Energy released during metabolism is captured by high-energy electrons carried by NADH and FADH 2. Energy from high-energy electrons moving along the electron transport system pumps H + from the matrix into the intermembrane space ELECTRON TRANSPORT SYSTEM

26 ATP Production: Electron Transport Figure 4-17, steps 1–3 H+H+ H+H+ H+H+ Mitochondrial matrix Matrix pool of H + 4e – e–e– Inner mitochondrial membrane CITRIC ACID CYCLE High-energy electrons O2O2 + 2 H 2 O H+H+ H+H+ Cytosol Outer mitochondrial membrane High-energy electrons from glycolysis H+H+ Intermembrane space Energy released during metabolism is captured by high-energy electrons carried by NADH and FADH 2. Energy from high-energy electrons moving along the electron transport system pumps H + from the matrix into the intermembrane space. Electrons at the end of the electron transport system are back to their normal energy state. They combine with H + and oxygen to form water ELECTRON TRANSPORT SYSTEM

27 H+H+ H+H+ H+H+ H+H+ Mitochondrial matrix Matrix pool of H + 4e – e–e– Inner mitochondrial membrane ADP + P i CITRIC ACID CYCLE High-energy electrons O2O2 + 2 H 2 O ATP H+H+ H+H+ Cytosol Outer mitochondrial membrane High-energy electrons from glycolysis H+H+ Intermembrane space Energy released during metabolism is captured by high-energy electrons carried by NADH and FADH 2. Energy from high-energy electrons moving along the electron transport system pumps H + from the matrix into the intermembrane space. Electrons at the end of the electron transport system are back to their normal energy state. They combine with H + and oxygen to form water. Potential energy captured in the H + concentration gradient is converted to kinetic energy when H + ions pass through the ATP synthase. Some of the kinetic energy is captured as ATP ATP synthase ELECTRON TRANSPORT SYSTEM Figure 4-17, steps 1–4 ATP Production: Electron Transport NADH and FADH2  ATP by oxidative phosphorylation

28 ATP Production: Energy Yield Figure Acetyl CoA Citric acid cycle NADHATPCO 2 FADH 2 2* +4 –2 22 NADHATPCO 2 FADH – ATP 6H2O6H2O 6 CO 2 2 ATP 0 NADH 4 AEROBIC METABOLISM C 6 H 12 O O 2 6 CO H 2 O ANAEROBIC METABOLISM C 6 H 12 O 6 2 C 3 H 6 O 3 (Lactic acid) * Cytoplasmic NADH sometimes yield only 1.5 ATP/NADH instead of 2.5 ATP/NADH. TOTALS GLYCOLYSISGLYCOLYSIS ELECTRON TRANSPORT SYSTEM 2 Pyruvate 1 Glucose High-energy electrons and H + 6 O 2 2 Pyruvate 2 Lactic acid 1 Glucose GLYCOLYSISGLYCOLYSIS

29 ATP Production: Large Biomolecules Glycogenolysis Glycogen Storage form of glucose in liver and skeletal muscle Converted to glucose or glucose 6-phosphate

30 Figure 4-20 ATP Production: Protein Catabolism and Deamination (a) Protein catabolism NADH + H + NAD + H 2 O H2OH2O Hydrolysis of peptide bond Peptide Protein or Peptide Amino acid Deamination NH 3 Organic acid Ammonia Amino acid (b) Deamination Glycolysis or citric acid cycle NH 4 + H+H+ Urea Ammonia Ammonium (c) + + NH 3

31 ATP Production: Lipolysis Figure 4-21 Triglyceride Fatty acid Cytosol Lipases digest triglycerides into glycerol and 3 fatty acids. Glycerol becomes a glycolysis substrate.  -oxidation chops 2-carbon acyl units off the fatty acids. Glucose Glycerol GLYCOLYSISGLYCOLYSIS Pyruvate Mitochondrial matrix CoA Acetyl CoA CO 2 CITRIC ACID CYCLE Acyl units become acetyl CoA and can be used in the citric acid cycle. Acyl unit  -oxidation

32 Synthesis: Gluconeogenesis Figure 4-22 Pyruvate Glucose Liver, kidney GLYCEROL AMINO ACIDS Glucose 6- phosphate GLUCONEOGENESISGLUCONEOGENESIS Glucose synthesis LACTATE

33 Synthesis: Lipids Figure 4-23 CoA Fatty acid synthetase Glycerol Fatty acids Triglyceride G L Y C O L Y S I S Glucose Acyl unit Glycerol can be made from glucose through glycolysis. Two-carbon acyl units from acetyl CoA are linked together by fatty acid synthetase to form fatty acids. One glycerol plus 3 fatty acids make a triglyceride. Pyruvate Acetyl CoA

34 Synthesis: Lipids Figure 4-23, steps 1 CoA Glycerol G L Y C O L Y S I S Glucose Acyl unit Glycerol can be made from glucose through glycolysis. Pyruvate Acetyl CoA 1 1

35 Synthesis: Lipids Figure 4-23, steps 1–2 Fatty acid synthetase Glycerol Fatty acids Acyl unit Two-carbon acyl units from acetyl CoA are linked together by fatty acid synthetase to form fatty acids. 2 2 CoA G L Y C O L Y S I S Glucose Acyl unit Glycerol can be made from glucose through glycolysis. Pyruvate Acetyl CoA 1 1

36 Synthesis: Lipids Figure 4-23, steps 1–3 CoA Fatty acid synthetase Glycerol Fatty acids Triglyceride G L Y C O L Y S I S Glucose Acyl unit Glycerol can be made from glucose through glycolysis. One glycerol plus 3 fatty acids make a triglyceride. Pyruvate Acetyl CoA Two-carbon acyl units from acetyl CoA are linked together by fatty acid synthetase to form fatty acids.

37 Synthesis: DNA to Protein Figure GENE ACTIVATION TRANSCRIPTION mRNA PROCESSING TRANSLATION POST-TRANSLATIONAL MODIFICATION GeneRegulatory proteins Constitutively active Induction Alternative splicing Processed mRNA Interference mRNA Protein chain Repression Regulated activity siRNA mRNA “silenced” rRNA in ribosomes tRNA Amino acids Folding and cross-links Assembly into polymeric proteins Addition of groups: sugars lipids -CH 3 phosphate Cleavage into smaller peptides Cytoplasm Nucleus

38 Synthesis: DNA to Protein Figure 4-25, steps 1 1 GENE ACTIVATION GeneRegulatory proteins Constitutively active InductionRepression Regulated activity Cytoplasm Nucleus

39 Synthesis: DNA to Protein Figure 4-25, steps 1–2 1 GENE ACTIVATION TRANSCRIPTION GeneRegulatory proteins Constitutively active Induction mRNA Repression Regulated activity Cytoplasm Nucleus 2

40 Synthesis: DNA to Protein Figure 4-25, steps 1–3 1 GENE ACTIVATION TRANSCRIPTION mRNA PROCESSING GeneRegulatory proteins Constitutively active Induction Alternative splicing Processed mRNA Interference mRNA Repression Regulated activity siRNA mRNA “silenced” Cytoplasm Nucleus 2 3

41 Synthesis: DNA to Protein Figure 4-25, steps 1–4 1 GENE ACTIVATION TRANSCRIPTION mRNA PROCESSING TRANSLATION GeneRegulatory proteins Constitutively active Induction Alternative splicing Processed mRNA Interference mRNA Protein chain Repression Regulated activity siRNA mRNA “silenced” rRNA in ribosomes tRNA Amino acids Cytoplasm Nucleus 2 3 4

42 Synthesis: DNA to Protein Figure 4-25, steps 1–5 1 GENE ACTIVATION TRANSCRIPTION mRNA PROCESSING TRANSLATION POST-TRANSLATIONAL MODIFICATION GeneRegulatory proteins Constitutively active Induction Alternative splicing Processed mRNA Interference mRNA Protein chain Repression Regulated activity siRNA mRNA “silenced” rRNA in ribosomes tRNA Amino acids Folding and cross-links Assembly into polymeric proteins Addition of groups: sugars lipids -CH 3 phosphate Cleavage into smaller peptides Cytoplasm Nucleus

43 Protein: Transcription Figure 4-26 RNA polymerase binds to DNA. The section of DNA that contains the gene unwinds. RNA bases bind to DNA, creating a single strand of mRNA. mRNA and the RNA polymerase detach from DNA, and the mRNA goes to the cytoplasm. RNA polymerase RNA polymerase mRNA strand released mRNA transcript RNA polymerase DNA Sense strand Antisense strand Site of nucleotide assembly Leaves nucleus after processing Lengthening mRNA strand RNA bases

44 Protein: Transcription Figure 4-27 Introns removed Transcribed sectionPromoter DNA Unprocessed mRNA Exons for protein #1Exons for protein #2 Gene Antisense strand Sense strand TRANSCRIPTION

45 Protein: Transcription and Translation Figure Translation Termination Outgoing “empty” tRNA tRNA mRNA Amino acid Ribosomal subunits Completed peptide Growing peptide chain mRNA Ribosome Incoming tRNA bound to an amino acid Anticodon Transcription mRNA processing Attachment of ribosomal subunits RNA polymerase DNA Nuclear membrane

46 Protein: Transcription and Translation Figure 4-28, steps 1 1 RNA polymerase DNA Nuclear membrane Transcription

47 Protein: Transcription and Translation Figure 4-28, steps 1–2 1 RNA polymerase DNA Nuclear membrane 2 Transcription mRNA processing

48 Protein: Transcription and Translation Figure 4-28, steps 1–3 1 RNA polymerase DNA Nuclear membrane 2 3 Transcription mRNA processing Attachment of ribosomal subunits

49 Protein: Transcription and Translation Figure 4-28, steps 1–4 1 Outgoing “empty” tRNA tRNA Amino acid Growing peptide chain mRNA Ribosome Incoming tRNA bound to an amino acid Anticodon RNA polymerase DNA Nuclear membrane Translation Transcription mRNA processing Attachment of ribosomal subunits

50 Protein: Transcription and Translation Figure 4-28, steps 1–5 1 Translation Termination Outgoing “empty” tRNA tRNA mRNA Amino acid Ribosomal subunits Completed peptide Growing peptide chain mRNA Ribosome Incoming tRNA bound to an amino acid Anticodon Transcription mRNA processing Attachment of ribosomal subunits RNA polymerase DNA Nuclear membrane

51 Protein: Post-Translational Modification Protein folding Cross-linkage Cleavage Addition of other molecules or groups Assembly into polymeric proteins

52 Figure 4-29 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Transport vesicles move the proteins from the ER to the Golgi complex. Gogli cisternae migrate from the cis-face toward the cell membrane. Some vesicles bud off the cisterna and move in a retrograde fashion. At the trans-face, some vesicles bud off to form lysosomes. Other vesicles become secretory vesicles that release their contents outside the cell. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

53 mRNA is transcribed from the genes in the DNA. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore Figure 4-29, steps 1 Protein: Post-Translational Modification and the Secretory Pathway 1 1

54 Figure 4-29, steps 1–2 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

55 Figure 4-29, steps 1–3 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

56 Figure 4-29, steps 1–4 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

57 Figure 4-29, steps 1–5 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

58 Figure 4-29, steps 1–6 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Transport vesicles move the proteins from the ER to the Golgi complex. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

59 Figure 4-29, steps 1–7 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Transport vesicles move the proteins from the ER to the Golgi complex. Gogli cisternae migrate from the cis-face toward the cell membrane. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

60 Figure 4-29, steps 1–8 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Transport vesicles move the proteins from the ER to the Golgi complex. Gogli cisternae migrate from the cis-face toward the cell membrane. Some vesicles bud off the cisterna and move in a retrograde fashion. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

61 Figure 4-29, steps 1–9 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Transport vesicles move the proteins from the ER to the Golgi complex. Gogli cisternae migrate from the cis-face toward the cell membrane. Some vesicles bud off the cisterna and move in a retrograde fashion. At the trans-face, some vesicles bud off to form lysosomes. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

62 Figure 4-29, steps 1–10 Protein: Post-Translational Modification and the Secretory Pathway mRNA is transcribed from the genes in the DNA. mRNA leaves the nucleus and attaches to cytosolic ribosomes, initiating translation and protein synthesis. Some proteins are released by free ribosomes into the cytosol or are targeted to specific organelles. Ribosomes attached to the rough endoplasmic reticulum direct proteins destined for packaging into the lumen of the RER. Proteins are modified as they pass through the lumen of the ER. Transport vesicles move the proteins from the ER to the Golgi complex. Gogli cisternae migrate from the cis-face toward the cell membrane. Some vesicles bud off the cisterna and move in a retrograde fashion. At the trans-face, some vesicles bud off to form lysosomes. Other vesicles become secretory vesicles that release their contents outside the cell. Cytosolic protein Endoplasmic reticulum Transport vesicle Retrograde Golgi-ER transport Cis-Golgi complex Lysosome or storage vesicle Trans-Golgi complex Secretory vesicle Cell membrane Extracellular space Cytosol Cisterna Nucleus mRNA DNA Ribosome Growing amino-acid chain Targeted proteins Peroxisome Mitochondrion Nuclear pore

63 Summary Energy Chemical Transport Mechanical Kinetic energy Potential energy

64 Summary Chemical reactions Reactants Products Reaction rate Free energy and activation energy Exergonic versus endergonic reactions Reversible versus irreversible reactions

65 Summary Enzymes Definition Characteristics Law of mass action Type of reactions

66 Summary Metabolism Catabolic versus anabolic reactions Control of metabolic pathways Aerobic versus anaerobic pathways

67 Summary ATP production Glycolysis Pyruvate metabolism Citric acid cycle Electron transport chain Glycogen, protein, and lipid metabolism

68 Summary Synthetic pathways Gluconeogenesis Lipid synthesis Protein synthesis Transcription Translation Post-translational modification


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