Microbiology Chapter 7: Microbial Metabolism

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Questions and Answers

What is the resulting molecule from the decarboxylation of pyruvate?

Pyruvate

Acetyl group (correct)

Glucose

NADH

What is the byproduct of glycolysis that yields energy?

FADH₂

NADH

2 ATP (correct)

Acetyl group

What is the role of NAD+ in glycolysis?

Electron donor

Electron acceptor (correct)

Carrier compound

Energy source

What is the final electron acceptor in aerobic respiration?

Oxygen Signup and view all the answers

Where do electron transfers take place in eukaryotic cells?

Mitochondria Signup and view all the answers

How many ATP molecules are produced during anaerobic respiration?

0 Signup and view all the answers

What is the purpose of fermentation?

To regenerate NAD⁺ from NADH Signup and view all the answers

How many ATP molecules are produced during glycolysis?

2 Signup and view all the answers

What is the primary role of enzymes in biochemical reactions?

To accelerate the rate of a reaction without being changed Signup and view all the answers

What is the effect of increasing the amount of enzyme or substrate on a biochemical reaction?

It increases the rate of the reaction Signup and view all the answers

What is the function of cofactors in enzyme activity?

To provide a non-protein component necessary for enzyme activity Signup and view all the answers

What is the effect of inhibitors on enzyme activity?

They decrease the rate of the reaction Signup and view all the answers

What is the primary source of organic molecules for heterotrophs?

Autotrophs Signup and view all the answers

What is the source of energy for chemoautotrophs?

Various molecules as a source of high energy electrons Signup and view all the answers

What type of organisms convert solar energy into chemical energy?

Phototrophic organisms Signup and view all the answers

What is the primary source of chemical energy for heterotrophic organisms?

Carbohydrates Signup and view all the answers

What is the purpose of phospholipases in microbial degradation?

To release fatty acids and phosphorylated head groups Signup and view all the answers

What is the result of catabolic pathways for lipids and proteins?

They are connected to the Krebs cycle Signup and view all the answers

What is the role of extracellular lipases in microbial degradation?

To release fatty acids from triglycerides Signup and view all the answers

What is the significance of microbial photosynthesis?

It is a significant supplier of chemical energy Signup and view all the answers

What are the six most common elements associated with organic molecules?

Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur Signup and view all the answers

What is the direction of energy flow in ecosystems?

From phototrophs to heterotrophic organisms Signup and view all the answers

What is the primary function of microbial metabolism?

To obtain energy and nutrients required for viability and reproduction Signup and view all the answers

What is anabolic reaction?

A type of endergonic reaction involved in biosynthesis Signup and view all the answers

What is the purpose of exergonic reactions?

To provide energy for endergonic reactions Signup and view all the answers

What is the result of glycolysis?

Formation of ATP through substrate-level phosphorylation Signup and view all the answers

What is the difference between respiration and fermentation?

Respiration produces ATP through oxygen-dependent reactions, while fermentation produces ATP through oxygen-independent reactions Signup and view all the answers

What is the role of enzymes in metabolic pathways?

To catalyze each reaction in a metabolic pathway Signup and view all the answers

What is the relationship between catabolic and anabolic reactions?

Catabolic reactions are the opposite of anabolic reactions Signup and view all the answers

What is the result of catabolic reactions?

Breakdown of complex molecules into simple molecular building blocks Signup and view all the answers

Study Notes

Microbial Metabolism

Microbial metabolism is a complex system of interwoven pathways coordinated by an intricate, multilayered regulatory network.
Microbes use various metabolic strategies to obtain energy and nutrients required for viability and reproduction.
There are two types of metabolic reactions: catabolic and anabolic reactions.

Metabolic Pathways

Cellular processes, such as building or breaking down complex molecules, occur through series of stepwise, interconnected chemical reactions called metabolic pathways.
Anabolism refers to endergonic metabolic pathways involved in biosynthesis, converting simple molecular building blocks into more complex molecules, and fueled by the use of cellular energy.

Energy and ATP

Energy is required to fuel anabolic reactions.
Exergonic reactions provide energy for endergonic reactions.
ATP is produced through cellular respiration and fermentation.

Fermentation

Fermentation is a metabolic process that produces ATP with a low ATP yield.
Fermentation uses an organic molecule as a final electron acceptor to regenerate NAD⁺ from NADH.
Fermentation does not involve an electron transport system, and no ATP is made by the fermentation process directly.

Respiration

Respiration is a metabolic process that produces ATP with a high ATP yield.
Cellular respiration begins when electrons are transferred from NADH and FADH₂ to a final inorganic electron acceptor (either oxygen in aerobic respiration or non-oxygen inorganic molecules in anaerobic respiration).

Glycolysis

Glycolysis is the first step in the breakdown of glucose, resulting in the formation of ATP, NADH, and two pyruvate molecules.
Glycolysis catalyzes the conversion of glucose to pyruvic acid (pyruvate).
Glycolysis releases energy to yield 2 ATP per glucose and transfers high-energy electrons (+H) to NAD⁺ to yield 2 NADH.

Catabolism of Carbohydrates, Lipids, and Proteins

Catabolic pathways for carbohydrates, lipids, and proteins eventually connect into glycolysis and the Krebs cycle.
Microbes can degrade a wide variety of carbon sources, including lipids and proteins.

Photosynthesis and the Importance of Light

Photosynthesis is the biochemical process by which phototrophic organisms convert solar energy (sunlight) into chemical energy.
Microbial photosynthesis is a significant supplier of chemical energy, fueling many diverse ecosystems.

Biogeochemical Cycles

Energy flows directionally through ecosystems, entering as sunlight for phototrophs or as inorganic molecules for chemoautotrophs.
The six most common elements associated with organic molecules (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur) take a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath earth's surface.

Enzymes

Almost all biochemical reactions are catalyzed by a specific enzyme: proteins that accelerate the rate of a reaction without being changed themselves.
Enzymes lower the activation energy (Ea) and provide a way to control or regulate biochemical reactions.

Control of Enzyme Activity

Biochemical reactions can be controlled by changes in enzyme activity, which can be influenced by:
1. Changes in the amount of enzyme or substrate.
2. Changes in temperature, pH, or salt.
3. Availability of any necessary cofactors.
4. Effect of inhibitors.

Principles of Energy Generation

All organisms depend on autotrophs, which can produce organic molecules from CO2, an inorganic carbon source.
The source of energy for autotrophic processes can be:
1. Light: photoautotrophs that carry out photosynthesis.
2. Chemical: chemoautotrophs that use various molecules as a source of high-energy electrons.

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Description

This quiz covers the complex system of microbial metabolism, including the various strategies microbes use to obtain energy and nutrients, and the biochemical reactions that occur in a cell or organism.