Enzyme Function and Classification Flashcards
What is the primary role of enzymes in biological systems?
To catalyze biochemical reactions by lowering the activation energy.
True or False: Enzymes are consumed in the reactions they catalyze.
False
Fill in the blank: Enzymes are typically __________ made from amino acids.
proteins
What is the term for the specific region on an enzyme where the substrate binds?
Active site
What happens to the enzyme after the reaction is complete?
It remains unchanged and can catalyze further reactions.
Multiple choice: Which factor does NOT affect enzyme activity? A) Temperature B) pH C) Color of the enzyme D) Substrate concentration
C) Color of the enzyme
What is the effect of temperature on enzyme activity?
Enzyme activity generally increases with temperature up to an optimal point, after which it decreases.
True or False: All enzymes function best at the same pH.
False
What are enzyme inhibitors?
Substances that decrease enzyme activity by binding to the enzyme.
Fill in the blank: The __________ model describes how enzymes and substrates fit together.
lock and key
Multiple choice: Which of the following is an example of a cofactor? A) Vitamin C B) Hemoglobin C) Glucose D) RNA
A) Vitamin C
What is a coenzyme?
A non-protein molecule that assists enzymes in catalyzing reactions.
True or False: Enzymes increase the rate of a reaction without changing the equilibrium of the reaction.
True
What is substrate specificity?
The ability of an enzyme to choose exact substrate from a group of similar chemical molecules.
Fill in the blank: Enzymes lower the __________ energy of a reaction.
activation
Multiple choice: Which of the following factors can denature an enzyme? A) High temperature B) Low pH C) Heavy metal ions D) All of the above
D) All of the above
What is the role of the enzyme’s active site?
To bind the substrate and facilitate the chemical reaction.
True or False: Enzymes can catalyze reactions in both directions.
True
What is the term for a molecule that increases enzyme activity?
Activator
Fill in the blank: The __________ theory suggests that the active site undergoes a conformational change upon substrate binding.
induced fit
What is the significance of enzyme kinetics?
It studies the rates of enzyme-catalyzed reactions to understand their efficiency and regulation.
Multiple choice: Which of the following best describes enzyme saturation? A) All enzymes are active B) All substrates are used up C) Enzyme activity is maximized D) Enzymes are denatured
C) Enzyme activity is maximized
What is feedback inhibition?
A regulatory mechanism where the end product of a metabolic pathway inhibits an enzyme involved in its synthesis.
Fill in the blank: Enzymes can be classified into __________ categories based on their function.
six
What is enzyme kinetics?
The study of the rates of enzyme-catalyzed reactions.
True or False: Enzyme kinetics can help to determine the mechanism of enzyme action.
True
What is the Michaelis-Menten equation used for?
To describe the rate of enzyme-catalyzed reactions.
Fill in the blank: The maximum rate of reaction is known as _____.
Vmax
What does Km represent in enzyme kinetics?
The substrate concentration at which the reaction rate is half of Vmax.
What is the relationship between Km and enzyme affinity for its substrate?
A lower Km indicates a higher affinity for the substrate.
True or False: Enzymes can catalyze reactions without any substrate.
False
What effect does increasing substrate concentration have on enzyme activity?
It increases the reaction rate until Vmax is reached.
What is a competitive inhibitor?
A substance that competes with the substrate for binding to the active site of the enzyme.
Fill in the blank: Non-competitive inhibitors bind to the enzyme at a site _____ from the active site.
different
What does the term ‘turnover number’ (kcat) refer to?
The number of substrate molecules converted to product per enzyme molecule per unit time.
What are allosteric enzymes?
Enzymes that undergo a conformational change upon binding of an effector, affecting their activity.
True or False: Enzyme activity can be affected by temperature and pH.
True
What happens to enzyme activity at extreme pH levels?
Enzyme activity typically decreases and can lead to denaturation.
What is the significance of enzyme saturation?
It indicates that all active sites of the enzyme are occupied by substrate.
Fill in the blank: The _____ model describes how substrates bind to enzymes.
lock-and-key
What term describes the effect of temperature on enzyme activity?
Thermal stability
What is the effect of a temperature increase on enzyme activity up to a certain point?
It generally increases the reaction rate.
True or False: Enzymes can only function in narrow pH ranges.
True
What does a Lineweaver-Burk plot represent?
A double-reciprocal plot of the Michaelis-Menten equation used to determine Km and Vmax.
What is an enzyme’s active site?
The region of the enzyme where substrate molecules bind and undergo a chemical reaction.
Fill in the blank: The _____ hypothesis suggests that the enzyme changes shape to fit the substrate.
induced fit
What is the role of cofactors in enzyme activity?
Cofactors assist enzymes in catalyzing reactions, often by stabilizing the enzyme-substrate complex.
What does the term ‘enzyme specificity’ refer to?
The ability of an enzyme to select for a specific substrate among many possible molecules.
What is the difference between reversible and irreversible inhibition?
Reversible inhibition can be overcome by increasing substrate concentration, while irreversible inhibition permanently inactivates the enzyme.
How do temperature and pH affect enzyme denaturation?
Extreme conditions can lead to structural changes that render the enzyme inactive.
What are enzymes?
Biological catalysts that speed up chemical reactions in living organisms.
True or False: Enzymes are consumed in the reactions they catalyze.
False
What is the primary classification of enzymes based on their function?
Enzymes are classified into six main categories: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases.
Fill in the blank: Enzymes that catalyze oxidation-reduction reactions are called ______.
oxidoreductases
Which class of enzymes transfers functional groups between molecules?
Transferases
What type of enzyme breaks down substrates by adding water?
Hydrolases
True or False: Lyases are enzymes that add or remove groups to form double bonds.
True
What is the function of isomerases?
They catalyze the rearrangement of molecular structures.
Which enzymes are responsible for joining two molecules together?
Ligases
Multiple Choice: Which of the following is NOT a class of enzymes? A) Oxidoreductases B) Transferases C) Amplifiers D) Ligases
C) Amplifiers
Fill in the blank: Enzymes can be affected by factors such as temperature, pH, and ______.
substrate concentration
What is the role of cofactors in enzyme activity?
Cofactors assist enzymes in catalyzing reactions.
True or False: All enzymes are proteins.
False
What are the two main types of cofactors?
Metal ions and coenzymes.
Short Answer: What are coenzymes?
Organic molecules that serve as cofactors.
Multiple Choice: Which enzyme class includes enzymes like pepsin and trypsin? A) Hydrolases B) Ligases C) Isomerases D) Lyases
A) Hydrolases
What is an enzyme’s active site?
The region where substrate molecules bind and undergo a chemical reaction.
True or False: Enzymes can only catalyze one type of reaction.
True
What is enzyme specificity?
The ability of an enzyme to select for a particular substrate.
Fill in the blank: The model that describes how enzymes and substrates interact is known as the ______ model.
lock and key
What is the effect of temperature on enzyme activity?
Enzyme activity typically increases with temperature up to an optimal point, after which it decreases.
Multiple Choice: Which factor does NOT affect enzyme activity? A) pH B) Temperature C) Color of the enzyme D) Substrate concentration
C) Color of the enzyme
Short Answer: What is enzyme inhibition?
A process where a molecule decreases an enzyme’s activity.
What are the two main types of enzyme inhibition?
Competitive and non-competitive inhibition.
True or False: Enzymes can be reused multiple times.
True
What is the significance of enzymes in biological reactions?
They lower the activation energy needed for reactions, thus speeding up the process.
What are enzyme inhibitors?
Substances that decrease the activity of enzymes.
True or False: Enzyme inhibitors can be used therapeutically.
True
Name one common type of enzyme inhibitor.
Competitive inhibitor
What is the mechanism of action for competitive inhibitors?
They bind to the active site of the enzyme, preventing substrate binding.
Fill in the blank: __________ inhibitors bind to an enzyme at a site other than the active site.
Non-competitive
What is the clinical relevance of ACE inhibitors?
They are used to treat hypertension and heart failure.
Name one example of a statin and its use.
Atorvastatin; it is used to lower cholesterol levels.
What is the role of MAO inhibitors in clinical practice?
They are used to treat depression by inhibiting monoamine oxidase.
True or False: All enzyme inhibitors are harmful.
False
What type of inhibitor is allopurinol?
It is a competitive inhibitor of xanthine oxidase.
Fill in the blank: __________ inhibitors are often used in cancer therapy.
Tyrosine kinase
What is the significance of beta-lactam antibiotics?
They inhibit bacterial cell wall synthesis.
What is the mechanism of action for irreversible inhibitors?
They permanently bind to the enzyme, leading to loss of activity.
Name a clinical condition treated with protease inhibitors.
HIV/AIDS
True or False: Enzyme inhibition can lead to drug interactions.
True
What is the effect of a competitive inhibitor on Vmax?
Vmax remains unchanged.
What is the primary function of cyclooxygenase (COX) inhibitors?
They reduce inflammation and pain.
Fill in the blank: __________ are used to inhibit blood clotting.
Anticoagulants
What is the function of angiotensin receptor blockers (ARBs)?
They block the action of angiotensin II, lowering blood pressure.
Name an example of a non-competitive inhibitor.
Phenylbutazone
What is the significance of sulfonamide antibiotics?
They inhibit bacterial folic acid synthesis.
True or False: Enzyme inhibitors can also act as substrates.
True
What type of enzyme inhibitor is used in the treatment of Alzheimer’s disease?
Acetylcholinesterase inhibitors
What is the effect of non-competitive inhibitors on Km?
Km increases.
What is the role of DPP-4 inhibitors in diabetes management?
They enhance insulin secretion and lower blood sugar levels.
Fill in the blank: __________ inhibitors are crucial in managing hypertension.
ACE
What is the mechanism of action of carbonic anhydrase inhibitors?
They decrease the production of bicarbonate and reduce fluid retention.
What is a coenzyme?
A coenzyme is a non-protein compound that is necessary for the functioning of an enzyme.
True or False: Coenzymes are typically made of proteins.
False
Fill in the blank: Coenzymes often serve as _____ for enzymes.
carriers
Which vitamin is a precursor to the coenzyme NAD+?
Niacin (Vitamin B3)
What role do coenzymes play in metabolic reactions?
They assist enzymes in catalyzing biochemical reactions.
Multiple Choice: Which of the following is a coenzyme? A) Hemoglobin B) NAD+ C) DNA
B) NAD+
What is the relationship between coenzymes and vitamins?
Many coenzymes are derived from vitamins.
True or False: Coenzymes can be permanently altered during a reaction.
False
Name one example of a coenzyme involved in energy metabolism.
Coenzyme A (CoA)
What is the function of coenzyme A?
It plays a critical role in the synthesis and oxidation of fatty acids and the metabolism of carbohydrates.
Multiple Choice: Which of the following is NOT a function of coenzymes? A) Act as a substrate B) Assist in enzyme activity C) Participate in electron transfer
A) Act as a substrate
Fill in the blank: Coenzymes often participate in _____ transfer reactions.
electron
What is the difference between coenzymes and cofactors?
Cofactors are non-protein molecules that assist enzymes, while coenzymes are a specific type of cofactor that are organic molecules.
True or False: Coenzymes are only required by a few enzymes.
False
What is FAD and what is its role?
FAD (flavin adenine dinucleotide) is a coenzyme involved in redox reactions.
Multiple Choice: Which coenzyme is involved in the transfer of acyl groups? A) NAD+ B) Coenzyme A C) ATP
B) Coenzyme A
Fill in the blank: The coenzyme _____ is essential for the metabolism of amino acids.
Pyridoxal phosphate (PLP)
What is the function of biotin as a coenzyme?
Biotin acts as a coenzyme in carboxylation reactions.
Multiple Choice: Which coenzyme is derived from riboflavin? A) NAD+ B) FAD C) CoA
B) FAD
What is the primary role of coenzymes in enzymatic reactions?
They help in the transfer of functional groups or electrons.
True or False: Coenzymes can be reused in multiple enzymatic reactions.
True
Name a coenzyme that is important in the synthesis of nucleotides.
NADPH
What is the role of tetrahydrofolate (THF) as a coenzyme?
THF is involved in one-carbon transfer reactions.
Multiple Choice: Which vitamin is associated with the coenzyme thiamine pyrophosphate (TPP)? A) Vitamin B1 B) Vitamin B2 C) Vitamin B3
A) Vitamin B1
Fill in the blank: The coenzyme _____ plays a critical role in the citric acid cycle.
NAD+
What are cofactors?
Cofactors are non-protein chemical compounds that are required for the biological activity of a protein, often an enzyme.
True or False: Cofactors can be organic or inorganic.
True
Fill in the blank: Cofactors that are organic molecules are known as ______.
coenzymes
Name a common example of an inorganic cofactor.
Zinc, iron, or magnesium
What role do cofactors play in enzymatic reactions?
Cofactors assist enzymes in catalyzing biochemical reactions.
Multiple choice: Which of the following is NOT a function of cofactors? A) Stabilizing enzyme structure B) Participating in chemical reactions C) Storing genetic information
C) Storing genetic information
What is the difference between a cofactor and a coenzyme?
A cofactor is a broader category that includes both organic and inorganic molecules, while a coenzyme specifically refers to organic cofactors.
True or False: All enzymes require cofactors to function.
False
Fill in the blank: The absence of a necessary cofactor can lead to ______ of an enzyme’s activity.
loss
What is a prosthetic group?
A prosthetic group is a type of cofactor that is tightly bound to an enzyme and is essential for its activity.
Multiple choice: Which vitamin acts as a coenzyme in various metabolic processes? A) Vitamin C B) Vitamin D C) Vitamin B12
C) Vitamin B12
What are metal ions, and how do they function as cofactors?
Metal ions are inorganic cofactors that help in stabilizing enzyme structures and participate in the catalytic process.
True or False: Cofactors can be permanently attached to enzymes.
True
Fill in the blank: Cofactors can increase the rate of reaction by providing a ______ environment.
favorable
What is the role of coenzymes in metabolism?
Coenzymes facilitate the transfer of specific atoms or functional groups from one molecule to another.
Multiple choice: Which cofactor is often involved in redox reactions? A) NAD+ B) ATP C) H2O
A) NAD+
What is an apoenzyme?
An apoenzyme is the protein part of an enzyme without its cofactor.
True or False: All cofactors are essential for enzyme activity.
False
Fill in the blank: The combination of an apoenzyme and its cofactor is called a ______.
holoenzyme
What happens to enzyme activity when cofactors are removed?
Enzyme activity typically decreases or ceases.
Multiple choice: Which of the following vitamins is a precursor for coenzymes? A) Vitamin A B) Vitamin B3 C) Vitamin E
B) Vitamin B3
What is an example of a cofactor involved in DNA synthesis?
Folic acid (Vitamin B9)
True or False: Cofactors can only be derived from dietary sources.
False
Fill in the blank: Some cofactors can be synthesized by the body, while others must be obtained from ______.
diet
What is the significance of cofactors in clinical biochemistry?
Cofactors are important in understanding enzyme function and the effects of deficiencies or excesses on health.
