Textbook Question
How do organisms control the rate of metabolic activities in their cells?
Ch. 5 - Microbial Metabolism
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302
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Table of contents
- Ch. 1 - A Brief History of Microbiology31
- Ch. 2 - The Chemistry of Microbiology28
- Ch. 3 - Cell Structure and Function39
- Ch. 4 - Microscopy, Staining, and Classification25
- Ch. 5 - Microbial Metabolism51
- Ch. 6 - Microbial Nutrition and Growth37
- Ch. 7 - Microbial Genetics51
- Ch. 8 - Recombinant DNA Technology21
- Ch. 9 - Controlling Microbial Growth in the Environment36
- Ch. 10 - Controlling Microbial Growth in the Body: Antimicrobial Drugs21
- Ch. 11 - Characterizing and Classifying Prokaryotes29
- Ch. 12 - Characterizing and Classifying Eukaryotes34
- Ch. 13 - Characterizing and Classifying Viruses, Viroids, and Prions23
- Ch. 14 - Infection, Infectious Diseases, and Epidemiology35
- Ch. 15 - Innate Immunity34
- Ch. 16 - Adaptive Immunity21
- Ch. 17 - Immunization and Immune Testing29
- Ch. 18 - Immune Disorders22
- Ch. 19 - Pathogenic Gram-Positive Bacteria25
- Ch. 20 - Pathogenic Gram-Negative Cocci and Bacilli28
- Ch. 21 - Rickettsias, Chlamydias, Spirochetes, and Vibrios25
- Ch. 22 - Pathogenic Fungi47
- Ch. 23 - Parasitic Protozoa, Helminths, and Arthropod Vectors44
- Ch. 24 - Pathogenic DNA Viruses23
- Ch. 25 - Pathogenic RNA Viruses30
- Ch. 26 - Applied and Industrial Microbiology29
- Ch. 27 - Microbial Ecology and Microbiomes22
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
Chapter 5, Problem 3
Examine the biosynthetic pathway for the production of the amino acids tryptophan, tyrosine, and phenylalanine in the figure. Where do the initial reactants (erythrose 4-phosphate and PEP) originate?
Verified step by step guidance1
Step 1: Identify the initial reactants in the biosynthetic pathway. According to the diagram, the pathway begins with erythrose 4-phosphate and phosphoenolpyruvic acid (PEP).
Step 2: Understand the metabolic origin of erythrose 4-phosphate. Erythrose 4-phosphate is an intermediate of the pentose phosphate pathway, which is a metabolic pathway parallel to glycolysis that generates NADPH and pentoses.
Step 3: Understand the metabolic origin of phosphoenolpyruvic acid (PEP). PEP is an intermediate in glycolysis, the central pathway for glucose catabolism, where it is formed from 2-phosphoglycerate and then converted to pyruvate.
Step 4: Recognize that these two molecules (erythrose 4-phosphate from the pentose phosphate pathway and PEP from glycolysis) combine to form 3-deoxy-D-arabino-heptulosonic acid 7-phosphate (DAHAP), the first committed step in the biosynthesis of aromatic amino acids.
Step 5: Conclude that the initial reactants originate from two distinct but interconnected metabolic pathways: erythrose 4-phosphate from the pentose phosphate pathway and PEP from glycolysis, linking central carbon metabolism to amino acid biosynthesis.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Origin of Erythrose 4-Phosphate
Erythrose 4-phosphate is an intermediate of the pentose phosphate pathway, a metabolic route parallel to glycolysis. It is derived from the rearrangement of sugar phosphates and serves as a precursor for aromatic amino acid biosynthesis.
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Pentose-Phosphate Pathway
Origin of Phosphoenolpyruvic Acid (PEP)
Phosphoenolpyruvic acid (PEP) is a high-energy intermediate produced in the glycolytic pathway. It is formed from 2-phosphoglycerate and plays a key role in energy transfer and as a substrate for biosynthetic reactions, including aromatic amino acid synthesis.
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02:45Acids
Biosynthesis of Aromatic Amino Acids and Feedback Inhibition
The biosynthesis of tryptophan, tyrosine, and phenylalanine begins with DAHAP, formed from erythrose 4-phosphate and PEP. Each amino acid regulates its own synthesis through feedback inhibition, where the end product inhibits the synthetase enzyme to maintain metabolic balance.
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Related Practice
Textbook Question
For the phrase given below, indicate the type of metabolism referred to, using the following choices:
a. Anabolism only
b. Both anabolism and catabolism (amphibolic)
c. Catabolism only
Is endergonic
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Textbook Question
For the phrase given below, indicate the type of metabolism referred to, using the following choices:
a. Anabolism only
b. Both anabolism and catabolism (amphibolic)
c. Catabolism only
Is exergonic
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Textbook Question
Indian tradition holds that storing water in brass pitchers prevents disease. Scientists have discovered that there is some truth in the tradition. The researchers collected river water samples and found fecal bacterial counts as high as 1 million bacteria per milliliter. However, they could detect no bacteria in the water after it had been stored for two days in traditional brass pitchers. Bacterial levels in plastic or earthenware containers remained high over the same period. How can brass, which is an alloy of copper mixed with zinc, make water safer to drink?
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Textbook Question
The initial catabolism of glucose occurs by glycolysis and/or the ________ and ________pathways.
Textbook Question
How does a noncompetitive inhibitor at a single allosteric site affect a whole pathway of enzymatic reactions?
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