4.1 - Enzyme Action Flashcards
Why are enzymes important in living organisms?
Enzymes are essential because they catalyze chemical reactions, allowing them to occur at a much faster rate without the need for extreme temperatures or pressures that would damage cells.
What would happen if enzymes were not present in living organisms?
Without enzymes, many of the chemical reactions necessary for life would not occur at the required speeds, making life processes impossible.
What are enzymes?
Enzymes are biological catalysts that are globular proteins. They interact with substrate molecules, speeding up reactions without needing harsh environmental conditions.
Why can’t living cells use extreme temperatures or pressures for chemical reactions?
Extreme temperatures and pressures would damage cell components, making them unsuitable for catalyzing reactions within living cells.
How do enzymes help chemical reactions occur in living organisms?
Enzymes lower the activation energy of reactions, allowing them to occur more quickly and efficiently under the mild conditions present in living cells.
What is the role of enzymes in anabolic reactions?
Enzymes catalyze anabolic reactions, which are building-up reactions, necessary for the synthesis and assembly of cell components like cellulose in plant cells and contractile proteins in muscles.
What are catabolic reactions and how are they related to enzymes?
Catabolic reactions are breaking-down reactions that release energy, such as the breakdown of glucose. These reactions are also catalyzed by enzymes.
How are large organic molecules obtained in living organisms?
Large organic molecules are obtained through the digestion of food, which is broken down by enzymes into smaller molecules like glucose.
What is metabolism and how do enzymes contribute to it?
Metabolism is the sum of all chemical reactions in a cell or organism. Enzymes control and organize these reactions, allowing them to proceed in an efficient and coordinated manner.
How do environmental conditions affect the rate of enzyme-catalyzed reactions?
Environmental conditions such as temperature, pressure, and pH can affect the rate of enzyme-catalyzed reactions, influencing the speed of cellular processes.
What is Vmax in the context of enzyme-catalyzed reactions?
Vmax is the maximum initial velocity or rate of an enzyme-catalyzed reaction, which is the highest rate at which the enzyme can operate, beyond which increasing the substrate concentration no longer increases the reaction rate.
Why do molecules need to collide in the right orientation for a reaction to occur?
For a reaction to happen, molecules must collide with the correct orientation so that the reactants can form products effectively. This increases the chances of a successful reaction.
How does increasing temperature and pressure affect the rate of reaction?
Increasing temperature and pressure speeds up the movement of molecules, leading to more frequent and successful collisions, which increases the overall rate of reaction.
What does the specificity of an enzyme refer to?
The specificity of an enzyme refers to the fact that each enzyme catalyzes only one specific type of chemical reaction, despite there being thousands of reactions in any given cell.
What is activation energy?
Activation energy is the minimum energy required for a chemical reaction to occur. It is the energy needed to start a reaction.
How do enzymes help reduce the activation energy of a reaction?
Enzymes help molecules collide successfully by lowering the activation energy needed, which makes reactions occur more easily under normal cellular conditions.
What are the two hypotheses for how enzymes reduce activation energy?
- The Lock and Key Hypothesis – the enzyme’s active site fits precisely with the substrate.
- The Induced Fit Hypothesis – the enzyme’s active site undergoes a conformational change when it binds to the substrate.
What is the active site of an enzyme?
The active site is a specific area within the tertiary structure of an enzyme that has a shape complementary to a particular substrate molecule, allowing the enzyme to catalyze a reaction.
What does the Lock and Key Hypothesis suggest about enzyme-substrate interaction?
The Lock and Key Hypothesis suggests that only a specific substrate will fit into the active site of an enzyme, just like a key fits into a lock. This forms an enzyme-substrate complex, leading to the formation of products.
What happens after the enzyme-substrate complex forms in the Lock and Key Hypothesis?
Once the enzyme-substrate complex forms, the substrate reacts, and the product or products are formed. These products are then released, leaving the enzyme unchanged and able to catalyze subsequent reactions.
How does the enzyme hold the substrate in the Lock and Key Hypothesis?
The enzyme holds the substrate in a way that the correct atom groups are close enough to react. The R groups in the active site form temporary bonds with the substrate, putting strain on its bonds, which helps the reaction proceed.
Describe the whole process of the Lock of Key Hypothesis.
- Enzymes + Substrates have specific shapes (complementary to each other)
- Active site of the enzymes is specific to the substrate.
- Bind forming enzyme-substrate complex.
- R groups of the amino acids in the active site interact with the substrate forming temporary bonds, and put strains on bonds in the substrate.
- Reaction occurs and new product(s) are made, forming an enzyme-product complex.
- A new product is released.
What is the Induced Fit Hypothesis?
The Induced Fit Hypothesis suggests that the enzyme’s active site changes shape slightly when the substrate enters, inducing strain on the substrate molecule. This change in shape lowers the activation energy required for the reaction to occur.
How does the Induced Fit Hypothesis differ from the Lock and Key Hypothesis?
Unlike the Lock and Key Hypothesis, where the enzyme’s active site is rigid, the Induced Fit Hypothesis proposes that the enzyme’s active site undergoes a slight shape change upon substrate binding, which helps weaken bonds in the substrate and lowers activation energy.
What happens during the initial interaction between the enzyme and substrate in the Induced Fit Hypothesis?
The initial interaction is weak, but it quickly induces changes in the enzyme’s tertiary structure. This strain weakens specific bonds in the substrate, facilitating the reaction and lowering the activation energy.
What are intracellular enzymes?
Intracellular enzymes are enzymes that act within cells to catalyze various metabolic reactions, such as the synthesis of polymers from monomers.
Why are enzymes essential for the synthesis of polymers from monomers?
Enzymes catalyze reactions that join monomers together to form polymers, such as making polysaccharides from glucose, which is crucial for the structure and function of cells.
What is the role of the enzyme catalase in cells?
Catalase breaks down hydrogen peroxide, a toxic by-product of metabolic reactions, into harmless oxygen and water, preventing the accumulation of this toxin in cells.
Where is the enzyme catalase found?
Catalase is found in both plant and animal tissues, where it helps protect cells from the toxic effects of hydrogen peroxide.
What are extracellular enzymes?
Extracellular enzymes are enzymes that are released from cells to catalyze the break down of large nutrient molecules outside the cells, making them small enough for absorption.
Why do large molecules, like proteins and polysaccharides, need to be broken down before entering cells?
Large molecules cannot enter cells directly through the cell surface membrane, so they must be broken down into smaller components to be absorbed by cells.
How are nutrients supplied to cells?
Nutrients, which are necessary for survival and growth, are found in the diet or environment of organisms and need to be continuously supplied to cells.
How do extracellular enzymes contribute to digestion?
Extracellular enzymes, such as amylase and trypsin, break down large nutrient molecules (like proteins and polysaccharides) outside the cell, allowing smaller molecules (like glucose and amino acids) to be absorbed by cells for nutrition.
How do single-celled organisms use extracellular enzymes?
Single-celled organisms, like bacteria and yeast, release enzymes into their environment to break down large molecules, such as proteins, into smaller molecules. The smaller products, such as glucose and amino acids, are then absorbed back into the cells.
How do multicellular organisms use extracellular enzymes?
In multicellular organisms, extracellular enzymes are used in the digestive system to break down large molecules from food so that smaller molecules can be absorbed into the bloodstream for use by cells.
What is the 2 examples of extracellular enzymes in human digestion?
Examples of extracellular enzymes involved in digestion in humans are amylase (for starch digestion) and trypsin (for protein digestion).
What is the role of amylase in digestion?
Amylase breaks down starch polymers into maltose, a disaccharide. It is produced by the salivary glands and pancreas and works in the mouth and small intestine.
What happens to maltose during digestion?
Maltose is further broken down into glucose, a monosaccharide, by the enzyme maltase, which is present in the small intestine. Glucose is small enough to be absorbed by the digestive system lining and enters the bloodstream.
What is the role of trypsin in protein digestion?
Trypsin is a protease that catalyzes the hydrolysis of peptide bonds in proteins, breaking them down into smaller peptides in the small intestine. Trypsin is produced in the pancreas and released into the small intestine, in pancreatic juice.
How are amino acids absorbed after protein digestion?
After trypsin and other proteases break down proteins into smaller peptides and amino acids, these amino acids are absorbed by the cells lining the digestive system and then enter the bloodstream.
