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Questions and Answers
What is the approximate percentage of genes that encode regulatory proteins in a typical cell?
What is the approximate percentage of genes that encode regulatory proteins in a typical cell?
Which of the following statements about typical cellular protein production is correct?
Which of the following statements about typical cellular protein production is correct?
What is one way isoenzymes can differ from one another?
What is one way isoenzymes can differ from one another?
Which categories contain the majority of regulatory proteins in a typical cell?
Which categories contain the majority of regulatory proteins in a typical cell?
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How does compartmentation in eukaryotic cells assist metabolic control?
How does compartmentation in eukaryotic cells assist metabolic control?
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Which of the following is a function of protein kinases?
Which of the following is a function of protein kinases?
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What is the primary role of metabolites in cellular metabolism?
What is the primary role of metabolites in cellular metabolism?
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Which enzyme is involved in the process of regulating gene expression through histone acetylation?
Which enzyme is involved in the process of regulating gene expression through histone acetylation?
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Which function does GAPDH perform outside of its metabolic role?
Which function does GAPDH perform outside of its metabolic role?
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Why is it important for metabolic enzymes to have different responses to allosteric modification?
Why is it important for metabolic enzymes to have different responses to allosteric modification?
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What is a primary goal of regulating interlocking metabolic processes?
What is a primary goal of regulating interlocking metabolic processes?
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How do hormones affect enzyme activity?
How do hormones affect enzyme activity?
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Which of the following correctly describes allosteric control?
Which of the following correctly describes allosteric control?
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Which organ is characterized as the most adaptable tissue?
Which organ is characterized as the most adaptable tissue?
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What is the role of insulin in gene regulation?
What is the role of insulin in gene regulation?
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What does the constant supply of ATP primarily help to protect?
What does the constant supply of ATP primarily help to protect?
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How many general types of insulin response elements are found in humans?
How many general types of insulin response elements are found in humans?
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What is the approximate concentration range of ATP that cells strive to maintain?
What is the approximate concentration range of ATP that cells strive to maintain?
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What does AMP-activated protein kinase (AMPK) do when activated?
What does AMP-activated protein kinase (AMPK) do when activated?
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Which of these is a critical indicator of a cell's energy status?
Which of these is a critical indicator of a cell's energy status?
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What occurs if the concentration of ATP drops significantly in a cell?
What occurs if the concentration of ATP drops significantly in a cell?
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How does AMPK affect metabolism?
How does AMPK affect metabolism?
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Which regulatory mechanism prevents glycolysis and gluconeogenesis from occurring simultaneously?
Which regulatory mechanism prevents glycolysis and gluconeogenesis from occurring simultaneously?
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What role do kinases and phosphatases play in metabolic regulation?
What role do kinases and phosphatases play in metabolic regulation?
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Which factor does NOT influence the distribution of different isozymes of a given enzyme?
Which factor does NOT influence the distribution of different isozymes of a given enzyme?
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What is the consequence of accumulating products of a biosynthetic pathway?
What is the consequence of accumulating products of a biosynthetic pathway?
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In what situations is AMPK activated?
In what situations is AMPK activated?
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What describes allosteric regulation in metabolic pathways?
What describes allosteric regulation in metabolic pathways?
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Study Notes
Metabolic Regulation
- Metabolic pathways are interconnected, and many metabolites are shared by multiple pathways.
- A typical cell makes approximately 30,000 proteins that catalyze thousands of different reactions.
- About 4,000 genes (~12% of all genes) encode regulatory proteins, including receptors and regulators of gene expression, as well as 500 different protein kinases.
- Cells must regulate interlocking metabolic processes simultaneously, handling fluctuating external conditions (e.g., nutrient and oxygen supply) without producing waste products.
- Time scales for metabolic regulation vary:
- Allosteric control occurs over seconds to hours.
- Covalent modification and changes in enzyme numbers take place over hours to days.
- Enzyme synthesis and degradation occurs hours to days.
- Regulation of enzyme activity can occur through changes in enzyme numbers, rate of synthesis and rate of degradation of molecules, or their activity.
- The liver is a highly adaptable tissue, capable of adjusting to dietary changes ranging from high carbohydrate to high fat diets, impacting gene transcription and protein expression.
- ATP is crucial to cellular function, and cells prioritize maintaining a constant level of ATP.
- Adenine nucleotides, such as ATP and AMP, are sensitive indicators of metabolic energy status.
- The ratio of ATP, ADP, NADH, NAD+, and NADPH, NADP+ are parameters for cellular function.
- Metabolic pathways are regulated through several mechanisms including coordination of pathways, partitioning metabolites, using fuel according to need, and shutting down biosynthetic pathways, and compartmentation.
- Coordinated regulation prevents futile cycles, where opposite pathways operate simultaneously, wasting cellular energy.
- Allosteric regulation is a very fast, local process triggered by changes in metabolites (substrates, products, or key cofactors). Examples include glycolysis, TCA cycle, fatty acid synthesis, and β-oxidation.
- Covalent modification through processes such as phosphorylation-dephosphorylation is another regulatory mechanism.
- Isoenzymes, different forms of an enzyme, vary in their kinetic or regulatory properties (e.g., Km values for hexokinase).
- Isoenzymes differ in cofactor usage (NADH/NADPH), cellular location (soluble or membrane-bound), and amino acid sequences. Examples include hexokinase and lactate dehydrogenase (LDH).
- Compartmentation through physical separation allows cells to control and regulate reactions and environments (e.g., pH, and potential gradients).
- Metabolic enzymes can have additional roles that are dependent upon location within the cell.
Insulin Regulation
- Insulin regulates the expression of over 150 genes.
- Humans have at least 7 general types of insulin response elements (REs or IREs) in promoters.
- The regulatory input into genes is complex and involves various transcription factors and response elements.
AMPK signaling Pathway
- An overview of AMPK pathway regulation is available in a YouTube video.
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Description
Explore the intricate world of metabolic regulation, where interconnected pathways and shared metabolites play a crucial role. Learn how cells manage to regulate numerous metabolic processes in response to varying conditions while maintaining efficiency and minimizing waste. This quiz encompasses key concepts of enzyme control and adaptation in metabolic pathways.
