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Questions and Answers
What is the minimum requirement for enzyme activity?
What is the minimum requirement for enzyme activity?
How does the velocity of an enzyme reaction change with an increase in enzyme concentration?
How does the velocity of an enzyme reaction change with an increase in enzyme concentration?
What is the shape of the curve obtained when velocity is plotted against substrate concentration?
What is the shape of the curve obtained when velocity is plotted against substrate concentration?
What is the order of the reaction when the velocity of the reaction is almost proportional to the substrate concentration?
What is the order of the reaction when the velocity of the reaction is almost proportional to the substrate concentration?
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What happens to the velocity of an enzyme reaction when the temperature increases up to a maximum?
What happens to the velocity of an enzyme reaction when the temperature increases up to a maximum?
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What is the name of the graph that shows the effect of substrate concentration on enzyme velocity?
What is the name of the graph that shows the effect of substrate concentration on enzyme velocity?
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What happens to the rate of reaction when the substrate concentration is much greater than Km?
What happens to the rate of reaction when the substrate concentration is much greater than Km?
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What is the term used to describe the rate of reaction when the velocity of the reaction is almost proportional to the substrate concentration?
What is the term used to describe the rate of reaction when the velocity of the reaction is almost proportional to the substrate concentration?
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What is the primary reason for the existence of an active site in an enzyme?
What is the primary reason for the existence of an active site in an enzyme?
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Which of the following amino acids is most frequently found at the active site?
Which of the following amino acids is most frequently found at the active site?
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What is the role of the catalytic site in the active site?
What is the role of the catalytic site in the active site?
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What is the type of bonds involved in the binding of substrate to the active site?
What is the type of bonds involved in the binding of substrate to the active site?
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What is the term for the small region in a big enzyme molecule where the active site is located?
What is the term for the small region in a big enzyme molecule where the active site is located?
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Why are enzymes specific in their function?
Why are enzymes specific in their function?
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What is the purpose of coenzymes in enzyme-catalyzed reactions?
What is the purpose of coenzymes in enzyme-catalyzed reactions?
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What is the result of the substrate binding to the active site?
What is the result of the substrate binding to the active site?
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What information does an enzyme's name typically indicate?
What information does an enzyme's name typically indicate?
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Which class of enzymes catalyzes the reaction of oxidation and reduction?
Which class of enzymes catalyzes the reaction of oxidation and reduction?
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What is the reaction catalyzed by the enzyme hexokinase?
What is the reaction catalyzed by the enzyme hexokinase?
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Which enzyme class includes lipase and choline esterase?
Which enzyme class includes lipase and choline esterase?
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What is the reaction catalyzed by the enzyme aldolase?
What is the reaction catalyzed by the enzyme aldolase?
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What is the EC number of the enzyme cytochrome oxidase?
What is the EC number of the enzyme cytochrome oxidase?
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Which enzyme class catalyzes the reaction of hydrolysis?
Which enzyme class catalyzes the reaction of hydrolysis?
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What is the reaction catalyzed by the enzyme alcohol dehydrogenase?
What is the reaction catalyzed by the enzyme alcohol dehydrogenase?
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What is the term applied to a substrate or an intermediate or a product in metabolic reactions?
What is the term applied to a substrate or an intermediate or a product in metabolic reactions?
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What is the primary purpose of catabolism?
What is the primary purpose of catabolism?
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What is the term for the degradative processes concerned with the breakdown of complex molecules to simpler ones?
What is the term for the degradative processes concerned with the breakdown of complex molecules to simpler ones?
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What is the term for the biosynthetic reactions involving the formation of complex molecules from simple precursors?
What is the term for the biosynthetic reactions involving the formation of complex molecules from simple precursors?
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What is the collective term for the entire spectrum of chemical reactions occurring in a living system?
What is the collective term for the entire spectrum of chemical reactions occurring in a living system?
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How many stages does catabolism occur in?
How many stages does catabolism occur in?
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What is the result of catabolic reactions?
What is the result of catabolic reactions?
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What is the term for a series of enzymatic reactions to produce specific products?
What is the term for a series of enzymatic reactions to produce specific products?
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What is the end result of the final oxidation of acetyl CoA in stage 3 of catabolism?
What is the end result of the final oxidation of acetyl CoA in stage 3 of catabolism?
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What is the primary function of Krebs cycle in catabolism?
What is the primary function of Krebs cycle in catabolism?
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What is the primary source of energy for anabolic reactions?
What is the primary source of energy for anabolic reactions?
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What is the main difference between anabolic and catabolic pathways?
What is the main difference between anabolic and catabolic pathways?
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What is the purpose of the first stage of catabolism?
What is the purpose of the first stage of catabolism?
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What type of reaction is catalyzed by specific enzymes in metabolic reactions?
What type of reaction is catalyzed by specific enzymes in metabolic reactions?
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What is the primary function of the citric acid cycle?
What is the primary function of the citric acid cycle?
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What is the role of NADH and FADH2 in catabolism?
What is the role of NADH and FADH2 in catabolism?
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Study Notes
Enzyme Classification
- Enzymes are given specific names indicating the substrate, coenzyme (if any), and the type of reaction catalyzed
- There are six main classes of enzymes: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases
- Each class has specific examples, such as:
- Oxidoreductases: alcohol dehydrogenase, cytochrome oxidase
- Transferases: hexokinase, transaminases
- Hydrolases: lipase, choline esterase, pepsin, urease
- Lyases: aldolase, fumarase, histidase
Factors Affecting Enzyme Activity
- The contact between the enzyme and substrate is essential for enzyme activity
- Factors that influence enzyme activity include:
- Concentration of enzyme: increasing enzyme concentration increases reaction velocity
- Concentration of substrate: increasing substrate concentration increases reaction velocity, but only up to a certain point
- Temperature: increasing temperature increases reaction velocity up to a maximum, then declines
- Active site: the specific region on the enzyme where the substrate binds
Active Site
- The active site is formed by the tertiary structure of the protein
- The active site is made up of amino acids (catalytic residues) that are distant from each other in the linear sequence
- The active site is flexible to promote specific substrate binding
- The active site has a substrate binding site and a catalytic site
- Coenzymes or cofactors are present at the active site
Vitamins and Coenzymes
- Coenzymes are non-protein molecules that assist enzymes in catalysis
- Examples of coenzymes include:
- Coenzyme A (CoA)
- Tetrahydrofolate (FH4)
- Biocytin
- Methyl cobalamin; Deoxyadenosyl cobalamin
Metabolism
- Metabolism is the collective term for all chemical reactions occurring in a living cell
- Metabolism is divided into two categories: catabolism and anabolism
- Catabolism is the breakdown of complex molecules to simpler ones, releasing energy
- Anabolism is the synthesis of complex molecules from simpler ones, requiring energy
Catabolism
- Catabolism occurs in three stages:
- Conversion of complex molecules into building blocks
- Formation of simple intermediates
- Final oxidation of acetyl CoA to CO2, releasing energy
- The Krebs cycle (or citric acid cycle) is a common metabolic pathway involved in the final oxidation of energy-rich molecules
Anabolism
- Anabolism requires the availability of precursors, energy, and reducing equivalents
- Anabolic reactions are dependent on the supply of energy and reducing equivalents
- The anabolic and catabolic pathways are not reversible and operate independently
Types of Metabolic Reactions
- There are four main types of biochemical reactions:
- Oxidation-reduction
- Group transfer
- Rearrangement and isomerization
- Make and break of carbon-carbon bonds
- These reactions are catalyzed by specific enzymes
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Description
This quiz covers the classification of enzymes, including their specific names, substrates, and reaction types. Learn about the different enzyme classes and their functions.
