Questions and Answers
What is a consequence of introducing water and oxygen to sulfide-oxidizing bacteria during mining processes?
What is the primary source of energy for eukaryotic organisms such as plants and animals?
What is the role of nitrogen-fixing bacteria in root nodules of plants?
What is a characteristic of prokaryotic metabolism?
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What is an example of an inorganic molecule that can be metabolized by prokaryotes?
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What is a consequence of microbial metabolism in some cases?
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What is the term used to describe all the chemical reactions inside a cell?
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What has been the role of microbial metabolism in earth's history?
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Which type of reaction releases energy and occurs spontaneously?
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What is an example of an organic molecule that can be metabolized by prokaryotes?
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What is the term for the metabolic pathways involved in biosynthesis?
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What is the term for the metabolic pathways that break down complex molecules into simpler ones?
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What is the primary source of energy for anabolic reactions?
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What is the term for the building or breaking down of complex molecules through a series of stepwise, interconnected chemical reactions?
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What type of molecule is converted into a more complex molecule during anabolic reactions?
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What is the expected outcome of an exergonic reaction?
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Why is glycolysis not oxygen dependent?
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What is the net yield of glycolysis?
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What happens to the three-carbon pyruvate molecules produced in glycolysis?
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What is the net yield of the Krebs cycle?
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What is a potential use of intermediate carbon molecules produced in the Krebs cycle?
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Why is studying metabolism in bacteria like E. coli useful?
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Why is carbohydrate catabolism often used as an example of metabolism in chemoheterotrophs?
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What is a benefit of learning about chemoheterotrophic metabolism?
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What is the function of enzymes such as amylase and cellulases?
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Which type of glycolysis is found in animals and most common in microbes?
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What is the endpoint of glycolysis?
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In which part of the cell does glycolysis take place?
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What is the purpose of the energy investment phase of glycolysis?
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What is the net energy yield of the energy payoff phase of glycolysis?
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What is the source of electrons used in the reduction of NAD+ to NADH in glycolysis?
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What is the primary function of glycolysis in some organisms?
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Study Notes
Metabolic Diversity of Prokaryotes
- Prokaryotes have great metabolic diversity, with important consequences for other forms of life.
- They can metabolize a wide range of organic and inorganic matter, including complex organic molecules and inorganic molecules and ions such as atmospheric nitrogen, molecular hydrogen, sulfide, manganese ions, ferrous iron, and ferric iron.
Acidic Mine Drainage
- Acidic mine drainage is a serious environmental problem resulting from the introduction of water and oxygen to sulfide-oxidizing bacteria during mining processes.
- These bacteria produce large amounts of sulfuric acid as a byproduct of their metabolism, resulting in a low-pH environment that can kill many aquatic plants and animals.
Nitrogen-Fixing Bacteria
- Some prokaryotes are essential to other life forms, such as nitrogen-fixing bacteria that convert atmospheric nitrogen into ammonia, providing a usable nitrogen source for plants.
- These bacteria live in root nodules of many plants.
Importance of Microbial Metabolism
- Microbial metabolism has been a driving force behind the development and maintenance of the planet's biosphere throughout earth's history.
- Microbes chemically convert substances into other forms, producing chemicals that can be harmful to other organisms or essential to the metabolism and survival of other life forms.
Metabolism
- Metabolism refers to all the chemical reactions inside a cell.
- It involves series of stepwise, interconnected chemical reactions called metabolic pathways.
- Metabolic pathways can be either anabolic (endergonic, energy-requiring, and involved in biosynthesis) or catabolic (exergonic, energy-releasing, and involved in breakdown of complex molecules).
Learning Objectives
- Describe why glycolysis is not oxygen dependent
- Define and describe the net yield of three-carbon molecules, ATP, and NADH from glycolysis
- Explain how three-carbon pyruvate molecules are converted into two-carbon acetyl groups that can be funneled into the Krebs cycle
- Define and describe the net yield of CO2, GTP/ATP, FADH2, and NADH from the Krebs cycle
- Explain how intermediate carbon molecules of the Krebs cycle can be used in a cell
Importance of Studying Metabolic Processes
- Extensive enzyme pathways exist for breaking down carbohydrates to capture energy in ATP bonds
- Catabolic pathways produce intermediate molecules used as building blocks for anabolism
- Studying metabolism in bacteria like E. coli helps understand human metabolism
- Learning about bacterial metabolism is useful for diagnosing pathogens and discovering antimicrobial therapies
- Understanding chemoheterotrophic metabolism serves as a basis for comparing other metabolic strategies used by microbes
Carbohydrate Catabolism
- Glycogen, starch, or cellulose are broken down into glucose by enzymes like amylase and cellulases
- Glucose is then catabolized through glycolysis, producing energy, reduced electron carriers, and precursor molecules for cellular metabolism
Glycolysis
- Glycolysis is the most common pathway for catabolizing glucose
- It produces energy, reduced electron carriers, and precursor molecules for cellular metabolism
- Glycolysis does not use oxygen, but can be coupled with aerobic or anaerobic respiration
- Glycolysis takes place in the cytoplasm of prokaryotic and eukaryotic cells
- The process begins with a single six-carbon glucose molecule and ends with two molecules of a three-carbon sugar called pyruvate
Embden-Meyerhof-Parnas (EMP) Pathway
- The EMP pathway is the most common type of glycolysis found in animals and microbes
- It consists of two distinct phases: energy investment and energy payoff
- The energy investment phase uses energy from two ATP molecules to modify a glucose molecule
- The energy payoff phase extracts energy by oxidizing glyceraldehyde 3-phosphate (G3P) to pyruvate, producing four ATP molecules and reducing two molecules of NAD+ to two molecules of NADH
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Description
Learn about the diverse metabolic processes of prokaryotes, specifically their role in acidic mine drainage and its effects on the environment.