BS 161 Chapter 5 Homework Questions

The movement of water into or out of a cell is an example of: a. osmosis. b. active transport. c. passive diffusion. d. lysis. e. osmosis and passive diffusion.

A protein that is temporarily associated with a biological membrane is a(n): a. transmembrane protein. b. peripheral membrane protein. c. integral membrane protein. d. transmembrane protein and an integral membrane protein.

Which part of a cholesterol molecule is polar? a. The OH group b. Both the four interconnected planar rings and the hydrocarbon tail c. The four interconnected planar rings d. The hydrocarbon tail

What factors are required for net movement of a substance to occur by facilitated diffusion? All of these choices are correct. a plasma membrane a transport protein a concentration gradient

A single molecule is always either hydrophobic or hydrophilic, and can never possess (at the same time) a region that is hydrophobic and a region that is hydrophilic. true false

Which one of the following is an example of secondary active transport? the use of more than one type of transport protein for the movement of a molecule the use of an electrochemical gradient of one molecule to move a second molecule the movement of potassium ions following the initial movement of sodium ions the use of a chemical gradient to generate an electrical gradient

If cells had single-layer membranes like micelles, how would the structures of transmembrane proteins be affected? The structures of transmembrane proteins would remain the same as if cells had lipid bilayers. Transmembrane proteins would possess a hydrophilic region in the cell interior and a hydrophobic region in the extracellular space. Transmembrane proteins would only possess hydrophobic regions. Transmembrane proteins would possess a hydrophobic region in the cell interior and a hydrophilic region in the extracellular space. Transmembrane proteins would only possess hydrophilic regions.

ow is a carrier protein different from a channel protein? Transport through carrier proteins depends on concentration gradients, but transport through channel proteins does not. Carrier proteins undergo conformational change so that they are open alternately to one side of the membrane or the other. Transport through a carrier does not depend on the random motion of molecules. Carrier proteins use ATP, but channel proteins do not.

Imagine a cell that has a membrane composed mostly of lipids with saturated fatty acid tails, and that this membrane also has low cholesterol content. What are the characteristics of this cell membrane? The lipids would be able to easily transition between the inner and outer layers of the bilayer constituting the cell membrane. The lipids contained in such a membrane would be highly mobile, and in near constant flux. Due to its cholesterol content, the cell membrane would remain fluid even at cold temperatures. The characteristics of this cell membrane will closely mirror those of a membrane composed of only unsaturated fatty acids. None of the other answer options is correct.

A researcher is using a modified version of FRAP. She has devised a technique that allows her to label all the peripheral membrane proteins with a fluorescent tag, and has bleached a specific area of the cell membrane. After 24 hours, she notices that fluorescence has returned to the bleached area. What can she deduce from this experiment? Peripheral membrane proteins can both move freely within the cell membrane and are akin to integral membrane proteins. Peripheral membrane proteins—like transmembrane proteins—are located within the cell membrane. Peripheral membrane proteins can move freely within the cell membrane. Peripheral membrane proteins may not be permanently associated with the cell membrane. Peripheral membrane proteins are akin to integral membrane proteins.

An amphipathic molecule is one that: has a head and tail domain. makes up a membrane. can fully dissolve in water. contains both polar and nonpolar regions.

During osmosis, water moves from a region of ______ to a region of ______. high solvent concentration; low solvent concentration high solute concentration; low solute concentration low solute concentration; high solute concentration "high solvent concentration; low solvent concentration" AND "low solute concentration; high solute concentration" are both correct answers.

What would be the outcome if the pump protein shown in Fig. 5.13a instead acted as a carrier that allowed protons to move from the extracellular fluid into the cytoplasm? Click to view full size. The number of protons on either side of the membrane would equalize. ATP could be synthesized from ADP + Pi and the number of protons on either side of the membrane would equalize. ATP could be synthesized from ADP + Pi. The proton electrochemical gradient would be reversed.

Predict how phospholipids arrange themselves when they are placed in a nonpolar solution. The phospholipid tails would orient toward the solution. The phospholipid heads would orient toward the solution. The phospholipid would form a liposome. The phospholipids would form a bilayer.

Which one of the following describes the hydrophilic component of cholesterol? a single hydrocarbon tail a phosphate group only a phosphate group and a chemical group called choline a hydroxyl group only a group of four planar rings and a hydroxyl group

Which one of the following is considered an integral membrane protein? a protein attached to a transmembrane protein via hydrogen bonding a protein attached to a phospholipid via ionic bonding with the head group of the lipid molecule a protein with its N-terminus in the cytoplasm and its C-terminus in the extracellular space a protein capable of diffusing throughout the cytoplasm of a cell

The sodium-potassium pump is an example of: channel-mediated diffusion. an antiporter. passive transport. a symporter. None of the answer options is correct.

RNA molecules are transported from the nucleus to the cytoplasm in eukaryotes through: aquaporins. sodium-potassium pumps. nuclear pores. budding off of the nuclear envelope. passive diffusion.

In intestinal epithelial cells, a transport protein moves glucose into the cytoplasm against its concentration gradient at the same time that it transports Na+ into the cell down its electrochemical gradient. Which of the following CORRECTLY describes this cotransport of glucose and sodium? Secondary active transport by an antiporter. Secondary active transport by a symporter. Primary active transport by an antiporter. Primary active transport by a symporter.

The lipid components of cellular membranes often include: phospholipids. phospholipids and cholesterol. fatty acids and cholesterol. phospholipids and fatty acids.

In response to seasonal changes in temperature, many organisms must alter the composition of their plasma membranes to maintain the proper degree of fluidity. As summer turns to fall and eventually into winter, which of the following would you predict you would observe in the plasma membranes of organisms that are unable to regulate their body temperature? an increase in phospholipid fatty acid chain length and a decrease in chain saturation an increase in phospholipid fatty acid chain length and an increase in chain saturation a decrease in phospholipid fatty acid chain length and an increase in chain saturation a decrease in phospholipid fatty acid chain length and a decrease in chain saturation

Which component of a phospholipid is found in the interior of a lipid bilayer? phosphate group glycerol fatty acids

Why does a phospholipid on the cytoplasmic side of the cell membrane rarely flip to the extracellular side if both environments are polar? The cholesterol does not allow lipids to move. The two sides have different functions and thus the phospholipid would not function properly. The cytoplasmic phospholipid is too big to pass through the membrane. The polar head group cannot pass through the nonpolar interior.

Long, saturated fatty acid tails _____ lipid mobility and _____ membrane fluidity. enhance; increase reduce; decrease maintain; decrease enhance; maintain reduce; increase

In lab, a dialysis tube is filled with a 15% sucrose solution, sealed, and placed in an unlabeled beaker filled with clear liquid. The dialysis tube is made of a semipermeable membrane that allows the free passage of water, but is not permeable to sucrose. After 2 hours, the bag in the beaker decreases in size and becomes flaccid. This observation suggests that at the beginning of the experiment, the solution in the bag was __________________ compared to the solution in the beaker. hypotonic hypertonic isotonic

Based on this observation, the contents of the beaker could have been: 25% sucrose. 5% sucrose. 15% sucrose.

How is the energy stored in a molecule of ATP used by the sodium-potassium pump? It is used to transport sodium ions into the cell. It is used to transport potassium ions out of the cell. All of these choices are correct. It is used to alter the conformation of the pump protein.

How is a carrier protein different from a channel protein? Carrier proteins use ATP, but channel proteins do not. Transport through a carrier does not depend on the random motion of molecules. Transport through carrier proteins depends on concentration gradients, but transport through channel proteins does not. Carrier proteins undergo conformational change so that they are open alternately to one side of the membrane or the other.

Which one of the following molecules would MOST likely require a transport protein to cross the plasma membrane of a red blood cell? CO2 O2 H2O C6H12O6

The beaker in the illustration below contains two solutions of salt with different concentrations (measured by molarity, M). The two solutions are separated by a membrane that is permeable to both salt and water. Which of the following will occur in this container? Net diffusion of water across the membrane, but not of salt. Diffusion of salt across the membrane, but not of water. Net diffusion of water from A to B and of salt from B to A. Net diffusion of salt from B to A, but no net diffusion of water. Net diffusion of water from B to A and of salt from A to B.

A beaker contains two solutions of glucose dissolved in water. The two solutions have different concentrations (measured by molarity, M) and are separated by a membrane that is permeable to water, but not to glucose. Which of the following statements is TRUE? The system will not reach equilibrium. There will be net movement of water from B to A. There will be net movement of glucose from B to A. The volume will increase in side B of the beaker.

In certain cells, a transport protein moves one calcium ion out of the cell against its concentration gradient while allowing the movement of three sodium ions into the cell down sodium's electrochemical gradient. Which of the following CORRECTLY describes this cotransport of calcium and sodium? primary active transport by an antiporter primary active transport by a symporter secondary active transport by a symporter secondary active transport by an antiporter

Why does active transport require ATP? An input of energy is needed to speed up the rate of facilitated diffusion. An input of energy is needed to allow the movement of molecules from an area of low concentration to one of higher concentration. An input of energy is needed to maintain the conformation of transport proteins. An input of energy is needed to both speed up the rate of facilitated diffusion and maintain the conformation of transport proteins.

Molecular oxygen (O2), which is required for the production of ATP by mitochondria, must pass through at least three membranes to get to the enzymes where it is used. O2 is also produced in chloroplasts and must pass through at least four membranes to be released from the plant. How does O2 move across biological membranes? O2 is hydrophilic and travels with water across the membranes. O2 is nonpolar and very small, so it can move by simple diffusion across the membrane. O2 undergoes a chemical reaction that binds it to other substances that are transported across the membranes. There are numerous protein transporters that allow O2 to travel across membranes.

Which of the following is not considered to be a part of the endomembrane system? Choice A., endoplasmic reticulum Choice B., mitochondria Choice C., Golgi Choice D., lysosome Choice E., plasma membrane

Most elements of the endomembrane system are connected by: Choice A., continuous membranes. Choice B., cytoskeleton. Choice C., vesicular trafficking.

Consider a protein that is targeted to be excreted to the outside of the plasma membrane. Where would this protein be located in the endoplasmic reticulum? Choice A., in the lumen (inside) of the E.R. Choice B., embedded as an integral membrane protein in the E.R. membrane Choice C., outside the E.R. as a peripheral membrane protein

Consider a protein that is targeted to be excreted to the outside of the plasma membrane. Where would this protein be located in the Golgi? Question 4 choices Choice A., in the lumen (inside) of the Golgi Choice B., embedded as an integral membrane protein in the Golgi membrane Choice C., outside the Golgi as a peripheral membrane protein

Consider a protein that is targeted to be an integral membrane protein on the surface of a cell. It has a specific functional domain (domain X) facing the external environment of the cell. How will this protein be oriented in the E.R.? Question 5 choices Choice A., It will be embedded in the E.R. membrane with domain X facing the lumen of the E.R. Choice B., It will be embedded in the E.R. membrane with domain X facing the cytoplasm of the cell. Choice C., It will be outside the E.R. as a peripheral membrane protein. Choice D., It will be completely within the E.R. lumen, not embedded in the membrane.

Consider a protein that is targeted to be an integral membrane protein on the surface of a cell. It has a specific functional domain (domain Y) facing the cytoplasm of the cell. How will this protein be oriented in the Golgi? Question 6 choices Choice A., It will be embedded in the Golgi membrane with domain Y facing the lumen of the E.R. Choice B., It will be embedded in the Golgi membrane with domain Y facing the cytoplasm of the cell. Choice C., It will be outside the Golgi as a peripheral membrane protein. Choice D., It will be completely within the Golgi lumen, not embedded in the membrane.

Many cell functions involve communication between cells via molecular signals that must be sent from one cell to be received by a target cell. Suppose the signal to be sent is a small protein. Where would you expect to find the protein in the Golgi? Question 7 choices Choice A., It would be an integral membrane protein with its functional domain on the lumen side of the membrane. Choice B., It would be an integral membrane protein with its functional domain on the cytoplasmic side of the membrane. Choice C., It would be in the lumen of the Golgi. Choice D., It would be on the exterior of the Golgi.

Which of the following would be synthesized in and processed by the rough endoplasmic reticulum and Golgi apparatus? fatty acids and phospholipids cytoskeletal proteins, actin and tubulin, which are found in the cytoplasm DNA polymerase and RNA polymerase lysosomal enzymes

Which of the following is TRUE about the presence or absence of plasma membranes? Plant cells and animal cells have a plasma membrane, but bacterial cells do not. Plant cells and bacterial cells have a plasma membrane, but animal cells do not. Only animal cells have a plasma membrane. Plant cells and bacterial cells have a cell wall. All cells have a plasma membrane.

Which one of the following is NOT considered part of the cytoplasm? the endoplasmic reticulum the cytoskeleton the nucleus None of the answer options is correct. the Golgi apparatus

Which one of the following organisms organizes its genome into a nucleoid? fungi archaea animals plants

Which eukaryotic organelle is associated with the breakdown of macromolecules? mitochondria lysosome endoplasmic reticulum the Golgi apparatus

How do eukaryotic plant and animal cells differ from one another? Animal cells have mitochondria but not chloroplasts, and plant cells have chloroplasts but not mitochondria. Animal cells have a plasma membrane and plant cells have a cell wall. Animal cells do not have chloroplasts and cell walls, and plant cells do. Animal cells have endoplasmic reticulum and plant cells don't.

Which of the following eukaryotic cell structures plays a role in protein trafficking and sorting? the Golgi apparatus lysosomes vacuoles mitochondria the endoplasmic reticulum

Which of the following sequences of events correctly describes the progress of a protein that will be secreted from the cell? 1. SRP binds to the growing polypeptide chain and to the ribosome. 2. Translation resumes. 3. SRP binds to its receptor. 4. The signal sequence is cleaved. 5. Protein synthesis begins in the cytosol. 6. Translation pauses. 3 → 6 → 1 → 2 → 4 → 5 5 → 6 → 1 → 3 → 2 → 4 5 → 1 → 6 → 3 → 2 → 4

If a mutation rendered the signal recognition particle nonfunctional, what would be the MOST obvious effect on the cell? All proteins normally secreted by the cell would remain partially formed and attached to the endoplasmic reticulum. All proteins normally secreted by the cell would remain in the cytosol. No proteins would arrive at their proper destinations within the cell. Proteins destined for the nucleus would remain in the cytosol. Translation would not be completed for most proteins.

Some diseases, such as Tay-Sachs, are caused by the defective breakdown of cellular components. Which of the following organelles is defective? ribosome plasma membrane lysosome endoplasmic reticulum Golgi apparatus

Insulin is a protein hormone that helps to control the level of glucose in the blood. It is secreted from specialized cells in the pancreas. Based on this information, which path does insulin take out of the cell? ER → Golgi apparatus → vesicle → exterior of cell ER → nucleus → cytosol → exterior of cell ER membrane → vesicle membrane → plasma membrane → exterior of cell nucleus → ER → Golgi apparatus → vesicle → exterior of cell vesicle → ER → Golgi apparatus → exterior of cell

During the translation of mRNA molecules, the new polypeptides are often directed to specific parts of the cell by the presence or absence of short sequences of amino acids called signal peptides. Which of the following would you expect to find in the polypeptides that will eventually fold to become enzymes important in photosynthesis, such as NADP+ reductase? no signal peptide a mitochondrial signal peptide a nuclear localization signal peptide a chloroplast signal peptide

Which of the following is TRUE of lysosomes? (Select all that apply.) The concentration of protons in the lysosome is often higher than in the cytoplasm. The pH is often higher inside the lysosome than in the cytoplasm. Lysosomal membranes often contain proteins that transport amino acids, simple sugars, and nucleotides. Proton pumps are sometimes found in the lysosomal membranes. Lysosomes fuse with other vesicles that contain macromolecules targeted for breakdown.

Where are ribosomes found inside a cell? both in the cytosol and attached to the rough endoplasmic reticulum attached to the rough endoplasmic reticulum attached to the Golgi apparatus in the cytosol

Individuals with a condition known as exercise intolerance suffer extreme fatigue from minimal exertion. Defects in which of the following structures are MOST likely responsible for this condition? lysosome Golgi apparatus endoplasmic reticulum mitochondria ribosomes