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Questions and Answers
Which type of reaction is catalyzed by oxidoreductases?
Which type of reaction is catalyzed by oxidoreductases?
What is the primary function of transferases?
What is the primary function of transferases?
Which enzyme is classified as a hydrolase?
Which enzyme is classified as a hydrolase?
What type of bond does a hydrolase act upon?
What type of bond does a hydrolase act upon?
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Hexokinase catalyzes the transfer of a phosphate group from ATP to glucose, producing glucose-6-phosphate and ADP. To what class of enzymes does hexokinase belong?
Hexokinase catalyzes the transfer of a phosphate group from ATP to glucose, producing glucose-6-phosphate and ADP. To what class of enzymes does hexokinase belong?
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Which of the following enzymes is involved in oxidation-reduction reactions?
Which of the following enzymes is involved in oxidation-reduction reactions?
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Which of the following is an example of a transferase?
Which of the following is an example of a transferase?
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What distinguishes hydrolases from other enzyme classes?
What distinguishes hydrolases from other enzyme classes?
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Which characteristic is NOT typically associated with enzymes?
Which characteristic is NOT typically associated with enzymes?
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What was a key early misconception regarding enzymes, before Buchner's experiment?
What was a key early misconception regarding enzymes, before Buchner's experiment?
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Which scientist's work directly contradicted Louis Pasteur's initial view on fermentation?
Which scientist's work directly contradicted Louis Pasteur's initial view on fermentation?
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Which statement best describes the role of the active site in an enzyme?
Which statement best describes the role of the active site in an enzyme?
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Which amino acid contains a sulfur atom in its side chain?
Which amino acid contains a sulfur atom in its side chain?
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Which of the following amino acids has a hydroxyl-containing side chain?
Which of the following amino acids has a hydroxyl-containing side chain?
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Which of the following contains an aromatic side chain?
Which of the following contains an aromatic side chain?
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Which of the following amino acids contains a basic side chain at pH 7?
Which of the following amino acids contains a basic side chain at pH 7?
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Which of the following exemplifies the catalytic efficiency property of enzymes?
Which of the following exemplifies the catalytic efficiency property of enzymes?
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Urease catalyzing the hydrolysis of urea into carbon dioxide and ammonia is an example of what kind of specificity?
Urease catalyzing the hydrolysis of urea into carbon dioxide and ammonia is an example of what kind of specificity?
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An enzyme that acts on molecules containing amino, methyl, or phosphate groups exhibits what type of specificity?
An enzyme that acts on molecules containing amino, methyl, or phosphate groups exhibits what type of specificity?
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Esterase, which cleaves ester bonds regardless of the molecular structure, is an example of which type of specificity?
Esterase, which cleaves ester bonds regardless of the molecular structure, is an example of which type of specificity?
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Fumarate hydratase acting on fumarate to produce malate demonstrates which type of specificity?
Fumarate hydratase acting on fumarate to produce malate demonstrates which type of specificity?
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Which of the following best describes the reaction conditions under which enzymes typically operate?
Which of the following best describes the reaction conditions under which enzymes typically operate?
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What is the rate enhancement range that characterizes the catalytic efficiency of enzymes?
What is the rate enhancement range that characterizes the catalytic efficiency of enzymes?
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Which of the following is NOT considered a key property of enzymes?
Which of the following is NOT considered a key property of enzymes?
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Flashcards
Hexokinase
Hexokinase
An enzyme that converts glucose and ATP into glucose-6-phosphate and ADP.
ATP
ATP
A molecule that provides energy for cellular processes.
Glucose-6-Phosphate
Glucose-6-Phosphate
The phosphorylated form of glucose, important for metabolism.
Oxidoreductases
Oxidoreductases
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Transferases
Transferases
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Hydrolases
Hydrolases
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Phosphotransferase
Phosphotransferase
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Deaminases
Deaminases
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Catalytic efficiency
Catalytic efficiency
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Specificity of enzymes
Specificity of enzymes
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Mild reaction conditions
Mild reaction conditions
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Absolute specificity
Absolute specificity
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Relative specificity
Relative specificity
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Group specificity
Group specificity
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Bond specificity
Bond specificity
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Stereospecificity
Stereospecificity
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Enzymes
Enzymes
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Active Site
Active Site
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Amino Acids
Amino Acids
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Hydrophobic Amino Acids
Hydrophobic Amino Acids
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Basic Amino Acids
Basic Amino Acids
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Acidic Amino Acids
Acidic Amino Acids
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Globular Proteins
Globular Proteins
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Ferments
Ferments
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Study Notes
Enzyme Introduction
- Enzymes are proteins
- They catalyze biochemical reactions
- They have a globular shape
- Enzymes are complex 3-D structures
Historical Perspectives
- Biochemistry history intertwined with enzyme research
- Enzymes first recognized in animal food digestion, sugar fermentation, and yeast processes
- Enzymes initially thought to be inseparable from living cells, like yeast.
- Eduard Buchner discovered that yeast extracts could ferment sugar to alcohol (demonstrating the concept of non-living enzymes)
- James Sumner and John Northrop later established that all enzymes are proteins and won the Nobel Prize.
- Later, catalytic RNA, also known as ribozymes, were discovered in the 1980s.
Enzyme Nomenclature
- Enzyme names often end in "-ase"
- Enzyme names often describe the enzyme's function (e.g., sucrase catalyzes sucrose hydrolysis)
- Some enzyme names describe both substrate and function (e.g., alcohol dehydrogenase oxidizes ethanol)
- Some enzymes use common names (e.g. pepsin, trypsin)
Enzyme Classification
- Enzymes classified into six classes by the International Union of Biochemists (IUB)
- Classification based on reactions catalyzed.
- Classes include:
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases
- Each enzyme has a unique classification number (e.g., EC:(2.7.1.1) HEXOKINASE)
Enzyme Properties
- Catalytic Efficiency: Enzymes are highly efficient, significantly speeding up reactions compared to uncatalyzed reactions.
- Specifity: Highly specific, interacting with particular substrates and catalyzing a single type of reaction
- Absolute specificity: catalyze only one reaction
- Relative specificity: includes Group (e.g, amino), Bond (e.g., type of bond), Stereospecificity (e.g., specific isomer)
- Mild Reaction Conditions: Operate under mild conditions (e.g., 37°C, physiological pH).
Enzyme Active Site
- The shape and chemical environment of the active site determine catalytic function
Enzyme Examples and Functions
- Oxidoreductases: Involved in oxidation-reduction reactions (e.g., lactate dehydrogenase). Examples include oxidases, peroxidases, and dehydrogenases
- Transferases: Transfer functional groups between molecules (e.g., transaminases, kinases).
- Hydrolases: Hydrolyze various chemical bonds by adding water atoms across chemical bonds (e.g. amylases, phosphatases). This includes peptidases, carbohydrases (like amylase, maltase, lactase), lipid hydrolyzing enzymes, deaminases.
- Lyases: Cleave various bonds by means that are not hydrolysis and oxidation. This includes fumarase, carbonic anhydrase.
- Isomerases: Catalyze isomerization changes within a single molecule by isomerizations(e.g. L-to-D).
- Lyases: Many other examples including aldehydes, alcohols, and other types of functional groups.
- Ligases/Synthases: Join two molecules through covalent bonds, using energy from ATP (e.g. glutamine synthetase)
- Synthases: Biosynthetic reactions that don't use energy from ATP
Enzyme Purification
- Preparation for further study.
Additional Notes
- Enzymes are essential for life, and their specific role and function are crucial in numerous biochemical processes.
- Many enzymes are called synthetases; however, some enzymes that catalyze biosynthetic reactions belong to classes other than ligases, called synthases.
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Description
This quiz covers the fundamental aspects of enzymes, including their structure, function, and historical significance in biochemistry. It highlights the discovery of enzymes and key figures in the field, such as Eduard Buchner and Nobel laureates James Sumner and John Northrop. Additionally, it explores the nomenclature of enzymes based on their activity and substrate interactions.