Chapter 8 And 7

You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely. What can you do to regain the activity of the enzyme?

You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down. What can you do to speed the reaction up again?

Consider a situation in which the enzyme is operating at optimum temperature and , and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

The Haber process is typically carried out at a temperature of approximately 500. What would happen to the rate of the forward reaction if the temperature were lowered to 100?

In general, enzymes are what kinds of molecules?

Enzymes work by _____.

An enzyme _____.

What name is given to the reactants in an enzymatically catalyzed reaction?

As a result of its involvement in a reaction, an enzyme _____.

The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of _____.

Which of these is exhibiting kinetic energy? 1. a rock on a mountain ledge 2. a space station orbiting Earth 3. the high-energy phosphate bonds of a molecule of ATP 4. an archer with a flexed bow 5. a person sitting on a couch while watching TV

"Conservation of energy" refers to the fact that _____.

Chemical energy is a form of _____ energy.

In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?

Which of these are by-products of cellular respiration?

Energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy?

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is correct?

Which of the following statements about equilibrium of chemical reactions is correct? 1. A reaction that is at equilibrium is not capable of doing any work. 2. Reactions can only go in the direction toward equilibrium. 3. Most reactions in a living cell are close to equilibrium. 4. The equilibrium point is where the system has the highest free energy 5. The equilibrium point of a reaction represents the least stable configuration for that reaction.

The reaction A --> B + C + heat is released in a(n) _____ reaction.

A(n) _____ reaction occurs spontaneously.

Which of these reactions requires a net input of energy from its surroundings?

In cells, what is usually the immediate source of energy for an endergonic reaction?

The reaction ADP + P --> ATP is a(n) _____ reaction.

The energy for an endergonic reaction comes from a(n) _____ reaction.

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

Select the INCORRECT association. 1. exergonic ... uphill 2 enzyme ... protein 3 potential energy ... positional energy 4 kinetic energy ... motion 5 exergonic ... spontaneous

What is energy coupling?

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation? 1. The compound is a negative allosteric regulator. 2.The compound is a competitive inhibitor. 3. The compound forms a covalent bond with one of the amino acid residues needed for enzyme activity. 4. The compound reduces disulfide bonds, causing the enzyme molecules to partially unfold. 5 The compound causes a cofactor to be lost from the enzyme.

Which of the following is NOT a way in which an enzyme can speed up the reaction that it catalyzes? 1.The enzyme binds a cofactor that interacts with the substrate to facilitate the reaction. 2. The active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction. 3. The binding of two substrates in the active site provides the correct orientation for them to react to form a product. 4 Binding of the substrate to the active site can stretch bonds in the substrate that need to be broken. 5 The active site can provide heat from the environment that raises the energy content of the substrate.

Which of the following would be unlikely to contribute to the substrate specificity of an enzyme? 1 The enzyme has an allosteric regulatory site. 2 A positive charge on the substrate is attracted to a negative charge in the active site of the enzyme. 3 The enzyme has the ability to change its configuration in response to the substrate binding. 4 A hydrophobic group on the substrate interacts with several hydrophobic amino acids on the enzyme. 5 A similar shape exists between a pocket on the surface of the enzyme and a functional group on the substrate.

Enzymes are described as catalysts, which means that they _____.

Which of the following statements about feedback regulation of a metabolic pathway is correct? 1 Accumulation of the product of the pathway increases further formation of that product. 2 The final product of a metabolic pathway is usually the compound that regulates the pathway. 3 The compound that regulates the pathway acts as a competitive inhibitor or a positive allosteric regulator. 4 The products of the pathway become the reactants for a different reaction, and thus products are unable to accumulate. 5 The enzyme that is regulated by feedback inhibition is usually the last enzyme in the metabolic pathway.

Select the correct statement about chemical energy, a term used by biologists to refer to potential energy available for release in a chemical reaction. 1 Light energy is converted to chemical energy during photosynthesis. 2 When a glucose molecule is catabolized to CO2 and H2O, chemical energy is lost. 3 A photosynthetic cell within a plant leaf produces chemical energy, stored within glucose molecules.

Which of the following statements about the role of ATP in cell metabolism is true? 1 The free energy released by ATP hydrolysis has a much more negative value than the hydrolysis of phosphate groups from other phosphorylated molecules. 2 The hydrolysis of the terminal phosphate group of ATP is associated with an exceptionally high release of free energy. 3 The energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule.

Which of the following statements about ATP (adenosine triphosphate) is correct? 1 The hydrolysis of ATP can supply energy needed for catabolic pathways. 2 The energy release on hydrolysis of ATP is the result of breaking a high-energy bond. 3 The hydrolysis of ATP is an endergonic process. 4 The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. 5 Almost all of the free energy released on the hydrolysis of ATP is released as heat.

Which of the following statements is true concerning catabolic pathways? 1. They build up complex molecules such as protein from simpler compounds. 2 They combine molecules into more energy-rich molecules. 3 They supply energy, primarily in the form of ATP, for the cell's work. 4 They are spontaneous and do not need enzyme catalysis. 5 They are endergonic.

Which of the following statements about a typical plasma membrane is correct? 1 Carbohydrates on the membrane surface are important in determining the overall bilayer structure. 2 The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell. 3 Phospholipids are the primary component that determines which solutes can cross the plasma membrane. 4 The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids. 5 The two sides of the plasma membrane have different lipid and protein composition.

Which of the following best describes the structure of a biological membrane? 1. two layers of phospholipids with proteins embedded between the two layers 2 a fluid structure in which phospholipids and proteins move freely between sides of the membrane 3 two layers of phospholipids with proteins either crossing the layers or on the surface of the layers 4 two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins 5 a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot

The permeability of a biological membrane to a specific polar solute may depend on which of the following? 1 the amount of cholesterol in the membrane 2 the types of transport proteins in the membrane 3 the phospholipid composition of the membrane 4 the presence of unsaturated fatty acids in the membrane 5 the types of polysaccharides present in the membrane

Which of the following is least likely to be important in holding the components of a biological membrane together? 1. polar interactions among the phospholipid head groups on the same surface of the membrane 2 hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane 3 hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane 4 covalent interactions between the phospholipid and protein components of the membrane 5 hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane

hich of the following factors does not affect membrane permeability? 1.The saturation of hydrocarbon tails in membrane phospholipids 2 The polarity of membrane phospholipids 3 The amount of cholesterol in the membrane 4 Temperature

How can a lipid be distinguished from a sugar?

True or false? Osmosis is a type of diffusion.

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

Which of the following particles could diffuse easily through a cell membrane? 1. Sodium ion (Na+) 2 Oxygen (O2) 3 Hydrogen ion (H+) 4 Glucose

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

What name is given to the process by which water crosses a selectively permeable membrane?

Which of the following statements about osmosis is correct? 1 If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell. 2 Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration. 3 If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis. 4 The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis. 5 Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment.

1n facilitated diffusion, what is the role of the transport protein?

What distinguishes facilitated diffusion from simple diffusion?

Which of the following transporters does not use passive transport to move molecules across a membrane? 1 Gramicidin ion channel 2 GLUT-1 glucose transporter 3 Valinomycin 4 Sodium-potassium pump

True or false? Active transport differs from passive transport in that active transport does not require an input of energy.

Which membrane protein would be used to move glucose across a membrane from a region of higher concentration to a region of lower concentration?

Which of the following statements is true about the net movement of an ion across a membrane by passive diffusion through a membrane channel? 1 For every ion that diffuses through the membrane, a different ion diffuses in the opposite direction. 2 There is a higher concentration of ions on the side of the membrane toward which the ion diffuses. 3 The charge on the other side of the membrane is generally the opposite of the ion's charge. 4 The cell expends energy as the ion passes through the membrane.

True or false? During active transport through the sodium-potassium pump, ATP hydrolysis provides the energy to pump three sodium ions into the cell for every two potassium ions pumped out of the cell.

Lactose transport by membrane proteins occurs under conditions in which the concentration of lactose inside the cell is higher than the concentration outside the cell. What type of transport is used to move lactose into the cell?

If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol?

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? 1. receptor-mediated endocytosis 2 passive diffusion of the glucose through the lipid bilayer 3 cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis 4 facilitated diffusion of the glucose using a carrier protein 5 movement of glucose into the cell through a glucose channel

Active and passive transport of solutes across a membrane typically differ in which of the following ways? 1 Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute. 2 Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. 3 Active transport is always faster than passive transport. 4 Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers. 5 Active transport is used for ions, passive transport is used for uncharged solutes.

Endocytosis moves materials _____ a cell via _____.

A white blood cell engulfing a bacterium is an example of _____.

Which of the following correctly describes some aspect of exocytosis or endocytosis? 1 Exocytosis and endocytosis change the surface area of the plasma membrane. 2 These two processes require the participation of mitochondria. 3 The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane. 4 Endocytosis and exocytosis involve active transport. 5 Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol.

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

Which of the following factors would tend to increase membrane fluidity? 1 a relatively high protein content in the membrane 2 a greater proportion of saturated phospholipids 3 a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses 4 a greater proportion of unsaturated phospholipids 5 a lower temperature

Which of the following processes includes all others? 1 transport of an ion down its electrochemical gradient 2 osmosis 3 diffusion of a solute across a membrane 4 facilitated diffusion 5 passive transport