Prokaryotes and Environmental Impact

Questions and Answers

What is a consequence of introducing water and oxygen to sulfide-oxidizing bacteria during mining processes?

Creation of a high-pH environment

Production of ammonia for plant use

Production of large amounts of sulfuric acid (correct)

Fixation of atmospheric nitrogen

What is the primary source of energy for eukaryotic organisms such as plants and animals?

Ferrous iron ions

Molecular hydrogen

Organic molecules (correct)

Inorganic molecules

What is the role of nitrogen-fixing bacteria in root nodules of plants?

To convert atmospheric nitrogen into ammonia (correct)

To break down cellulose

To oxidize sulfide ions

To produce sulfuric acid

What is a characteristic of prokaryotic metabolism?

Ability to metabolize a wide range of organic and inorganic matter Signup and view all the answers

What is an example of an inorganic molecule that can be metabolized by prokaryotes?

Molecular hydrogen Signup and view all the answers

What is a consequence of microbial metabolism in some cases?

Production of chemicals that can be harmful to other organisms Signup and view all the answers

What is the term used to describe all the chemical reactions inside a cell?

Metabolism Signup and view all the answers

What has been the role of microbial metabolism in earth's history?

A driving force behind the development and maintenance of the planet's biosphere Signup and view all the answers

Which type of reaction releases energy and occurs spontaneously?

Exergonic reaction Signup and view all the answers

What is an example of an organic molecule that can be metabolized by prokaryotes?

Cellulose Signup and view all the answers

What is the term for the metabolic pathways involved in biosynthesis?

Anabolism Signup and view all the answers

What is the term for the metabolic pathways that break down complex molecules into simpler ones?

Catabolism Signup and view all the answers

What is the primary source of energy for anabolic reactions?

Cellular energy Signup and view all the answers

What is the term for the building or breaking down of complex molecules through a series of stepwise, interconnected chemical reactions?

Metabolic pathways Signup and view all the answers

What type of molecule is converted into a more complex molecule during anabolic reactions?

Simple molecular building block Signup and view all the answers

What is the expected outcome of an exergonic reaction?

Energy is released Signup and view all the answers

Why is glycolysis not oxygen dependent?

Because it does not require electron transport chains Signup and view all the answers

What is the net yield of glycolysis?

Three-carbon molecules, ATP, and NADH Signup and view all the answers

What happens to the three-carbon pyruvate molecules produced in glycolysis?

They are converted into two-carbon acetyl groups Signup and view all the answers

What is the net yield of the Krebs cycle?

CO2, GTP/ATP, FADH2, and NADH Signup and view all the answers

What is a potential use of intermediate carbon molecules produced in the Krebs cycle?

They can be used as building blocks for anabolism Signup and view all the answers

Why is studying metabolism in bacteria like E. coli useful?

Because it helps us understand human metabolism Signup and view all the answers

Why is carbohydrate catabolism often used as an example of metabolism in chemoheterotrophs?

Because it is a common metabolic pathway Signup and view all the answers

What is a benefit of learning about chemoheterotrophic metabolism?

It serves as a basis for comparing other metabolic strategies Signup and view all the answers

What is the function of enzymes such as amylase and cellulases?

To break down glycosidic bonds between glucose monomers Signup and view all the answers

Which type of glycolysis is found in animals and most common in microbes?

Embden-Meyerhof-Parnas (EMP) pathway Signup and view all the answers

What is the endpoint of glycolysis?

Pyruvate Signup and view all the answers

In which part of the cell does glycolysis take place?

Cytoplasm Signup and view all the answers

What is the purpose of the energy investment phase of glycolysis?

To modify a glucose molecule for splitting Signup and view all the answers

What is the net energy yield of the energy payoff phase of glycolysis?

4 ATP molecules Signup and view all the answers

What is the source of electrons used in the reduction of NAD+ to NADH in glycolysis?

Glucose Signup and view all the answers

What is the primary function of glycolysis in some organisms?

To generate ATP and precursor molecules for cellular metabolism Signup and view all the answers

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.