BIO 202 test 2

Which of the following is both in eukaryotic and prokaryotic cells? A. nucleus B. mitochondrion C. vacuole D. ribosomesd. ribosomesTay-Sachs disease is a genetic disorder that results in the destruction of neurons due to buildup of sphingolipids in the cells. Which organelle is malfunctioning in Tay-Sachs? A. lysosomes B. endoplasmic reticulum C. peroxisome D. mitochondrialysosomeWhich of the following is not a component of the endomembrane system? A. mitochondion B. golgi apparatus C. endoplasmic reticulum D. lysosomemitochondrionThe process by which cell engulfs a foreign particle is known as: A. endosymiosis B. phagosytosis C. hydrolysis D. membrane synthesisphagocytosisWhich of the following is most likely to have the greatest concentration of smooth endoplasmic reticulum? A. a cell that secrets enzymes B. a cell that destroys pathogens C. a cell that makes steroids hormones D. a cell that engages in photosynthesisa cell that makes steroid hormonesWhich of the following sequences correctly lists in order the steps involved in the incorporation of a proteinaceous molecule within a cell? a. protein synthesis of the protein on the ribosome; modification in the Golgi apparatus; packaging in the endoplasmic reticulum; tagging in the vesicle b. synthesis of the protein on the lysosome; tagging in the Golgi; packaging in the vesicle; distribution in the endoplasmic reticulum c. synthesis of the protein on the ribosome; modification in the endoplasmic reticulum; tagging in the Golgi; distribution via the vesicle d. synthesis of the protein on the lysosome; packaging in the vesicle; distribution via the Golgi; tagging in the endoplasmic reticulumsynthesis of the protein on the ribosome; modification in the endoplasmic reticulum; tagging in the Golgi; distribution via the vesicleCongenital disorders of glycosylation are a growing class of rare diseases. Which organelle would be most commonly involved in the glycoprotein disorder portion of the group? a. RER b. ribosomes c. endosomes d. Golgi apparatusGolgi apparatusWhich of the following have the ability to disassemble and reform quickly? a. microfilaments and intermediate filaments b. microfilaments and microtubules c. intermediate filaments and microtubules d. only intermediate filamentsmicrofilaments and microtubulesWhich of the following do not play a role in intracellular movement? a. microfilaments and intermediate filaments b. microfilaments and microtubules c. intermediate filaments and microtubules d. only intermediate filamentsonly intermediate filamentsIn humans, _____ are used to move a cell within its environment while _____ are used to move the environment relative to the cell. a. cilia, pseudopodia b. flagella; cilia c. microtubules; flagella d. microfilaments; microtubulesflagella; ciliaWhich of the following are only in plant cells? a. gap junctions b. desmosomes c. plasmodesmata d. tight junctionsplasmodesmataThe key components of desmosomes are cadherins and __________. a. actin b. microfilaments c. intermediate filaments d. microtubulesintermediate filamentsDiseased animal cells may produce molecules that activate death cascades to kill the cells in a controlled manner. Why would neighboring healthy cells also die? a. The death molecule is passed through desmosomes. b. The death molecule is passed through plasmodesmata. c. The death molecule disrupts the extracellular matrix. d. The death molecule passes through gap junctions.The death molecule passes through gap junctions.In your everyday life, you have probably noticed that certain instruments are ideal for certain situations. For example, you would use a spoon rather than a fork to eat soup because a spoon is shaped for scooping, while soup would slip between the tines of a fork. The use of ideal instruments also applies in science. In what situation(s) would the use of a light microscope be ideal, and why?A light microscope would be ideal when viewing a small living organism, especially when the cell has been stained to reveal details.In what situation(s) would the use of a scanning electron microscope be ideal, and why?A scanning electron microscope would be ideal when you want to view the minute details of a cell's surface, because its beam of electrons moves back and forth over the surface to convey the image.In what situation(s) would a transmission electron microscope be ideal, and why?A transmission electron microscope would be ideal for viewing the cell's internal structures, because many of the internal structures have membranes that are not visible by the light microscope.What are the advantages and disadvantages of each of these types of microscopes?The advantages of light microscopes are that they are easily obtained, and the light beam does not kill the cells. However, typical light microscopes are somewhat limited in the amount of detail they can reveal. Electron microscopes are ideal because you can view intricate details, but they are bulky and costly, and preparation for the microscopic examination kills the specimen.Explain how the formation of an adult human follows the cell theory.The cell theory states:1. All living things are made of cells.2. Cells are the most basic unit of life.3. New cells arise from existing cells.All humans are multicellular organisms whose smallest building blocks are cells. Adult humans begin with the fusion of a male gamete cell with a female gamete cell to form a fertilized egg (single cell). That cell then divides into two cells, which each divides into two more cells, and so forth until all the cells of a human embryo are made. As the embryo passes through all the developmental stages to make an adult human, the cells that are added arise from division of existing cells.Antibiotics are medicines that are used to fight bacterial infections. These medicines kill prokaryotic cells without harming human cells. What part or parts of the bacterial cell do you think antibiotics target? Why?The cell wall would be targeted by antibiotics as well as the bacteria's ability to replicate. This would inhibit the bacteria's ability to reproduce, and it would compromise its defense mechanisms.Explain why not all microbes are harmful.Some microbes are beneficial. For instance, E. coli bacteria populate the human gut and help break down fiber in the diet. Some foods such as yogurt are formed by bacteria.You already know that ribosomes are abundant in red blood cells. In what other cells of the body would you find them in great abundance? Why?Ribosomes are abundant in muscle cells as well because muscle cells are constructed of the proteins made by the ribosomes.What are the structural and functional similarities and differences between mitochondria and chloroplasts?Both are similar in that they are enveloped in a double membrane, both have an intermembrane space, and both make ATP. Both mitochondria and chloroplasts have DNA, and mitochondria have inner folds called cristae and a matrix, while chloroplasts have chlorophyll and accessory pigments in the thylakoids that form stacks (grana) and a stroma.Why are plasma membranes arranged as a bilayer rather than a monolayer?The plasma membrane is a bilayer because the phospholipids that create it are amphiphilic (hydrophilic head, hydrophobic tail). If the plasma membrane was a monolayer, the hydrophobic tails of the phospholipids would be in direct contact with the inside of the cell. Since the cytoplasm is largely made of water, this interaction would not be stable, and would disrupt the plasma membrane of the cell as the tails were repulsed by the cytoplasm (in water, phospholipids spontaneously form spherical droplets with the hydrophilic heads facing outward to isolate the hydrophobic tails from the water). By having a bilayer, the hydrophilic heads are exposed to the aqueous cytoplasm and extracellular space, while the hydrophobic tails interact with each other in the middle of the membrane.In the context of cell biology, what do we mean by form follows function? What are at least two examples of this concept?"Form follows function" refers to the idea that the function of a body part dictates the form of that body part. As an example, compare your arm to a bat's wing. While the bones of the two correspond, the parts serve different functions in each organism and their forms have adapted to follow that function.In your opinion, is the nuclear membrane part of the endomembrane system? Why or why not? Defend your answer.Since the external surface of the nuclear membrane is continuous with the rough endoplasmic reticulum, which is part of the endomembrane system, then it is correct to say that it is part of the system.What are the similarities and differences between the structures of centrioles and flagella?Centrioles and flagella are alike in that they are made up of microtubules. In centrioles, two rings of nine microtubule "triplets" are arranged at right angles to one another. This arrangement does not occur in flagella.How do cilia and flagella differ?Cilia and flagella are alike in that they are made up of microtubules. Cilia are short, hair-like structures that exist in large numbers and usually cover the entire surface of the plasma membrane. Flagella, in contrast, are long, hair-like structures; when flagella are present, a cell has just one or two.Describe how microfilaments and microtubules are involved in the phagocytosis and destruction of a pathogen by a macrophage.A macrophage engulfs a pathogen by rearranging its actin microfilaments to bend the plasma membrane around the pathogen. Once the pathogen is sealed in an endosome inside the macrophage, the vesicle is walked along microtubules until it combines with a lysosome to digest the pathogen.Compare and contrast the boundaries that plant, animal, and bacteria cells use to separate themselves from their surrounding environment.All three cell types have a plasma membrane that borders the cytoplasm on its interior side. In animal cells, the exterior side of the plasma membrane is in contact with the extracellular environment. However, in plant and bacteria cells, a cell wall surrounds the outside of the plasma membrane. In plants, the cell wall is made of cellulose, while in bacteria the cell wall is made of peptidoglycan. Gram-negative bacteria also have an additional capsule made of lipopolysaccharides that surrounds their cell wall.How does the structure of a plasmodesma differ from that of a gap junction?They differ because plant cell walls are rigid. Plasmodesmata, which a plant cell needs for transportation and communication, are able to allow movement of really large molecules. Gap junctions are necessary in animal cells for transportation and communication.Explain how the extracellular matrix functions.The extracellular matrix functions in support and attachment for animal tissues. It also functions in the healing and growth of the tissue.Pathogenic E. coli have recently been shown to degrade tight junction proteins during infection. How would this provide an advantage to the bacteria?E. coli infections generally cause food poisoning, meaning that the invading bacteria cross from the lumen of the gut into the rest of the body. Tight junctions hold the epithelial layer that lines the digestive tract together so that the material that crosses into the body is tightly regulated. One way E. coli can avoid this regulation is to destroy the tight junctions so that it can enter the body between the epithelial cells, rather than having to go through the cells.A doctor injects a patient with what the doctor thinks is an isotonic saline solution. The patient dies, and an autopsy reveals that many red blood cells have been destroyed. Do you think the solution the doctor injected was really isotonic?No, it must have been hypotonic as a hypotonic solution would cause water to enter the cells, thereby making them burst.Injecting a potassium solution into a person's blood is lethal. Capital punishment and euthanasia utilize this method in their subjects. Why do you think a potassium solution injection is lethal?Cells typically have a high concentration of potassium in the cytoplasm and are bathed in a high concentration of sodium. Injection of potassium dissipates this electrochemical gradient. In heart muscle, the sodium/potassium potential is responsible for transmitting the signal that causes the muscle to contract. When this potential is dissipated, the signal can't be transmitted, and the heart stops beating. Potassium injections are also used to stop the heart from beating during surgery.If the pH outside the cell decreases, would you expect the amount of amino acids transported into the cell to increase or decrease?A decrease in pH means an increase in positively charged H+ ions, and an increase in the electrical gradient across the membrane. The transport of amino acids into the cell will increase.Which plasma membrane component can be either found on its surface or embedded in the membrane structure? a. protein b. cholesterol c. carbohydrate d. phospholipidproteinWhich characteristic of a phospholipid contributes to the fluidity of the membrane? a. its head b. cholesterol c. a saturated fatty acid tail d. double bonds in the fatty acid taildouble bonds in the fatty acid tailWhat is the primary function of carbohydrates attached to the exterior of cell membranes? a. identification of the cell b. flexibility of the membrane c. strengthening the membrane d. channels through membraneidentification of the cellA scientist compares the plasma membrane composition of an animal from the Mediterranean coast with one from the Mojave Desert. Which hypothesis is most likely to be correct? a. The cells from the Mediterranean coast animal will have more fluid plasma membranes. b. The cells from the Mojave Desert animal will have a higher cholesterol concentration in the plasma membranes. c. The cells' plasma membranes will be indistinguishable. d. The cells from the Mediterranean coast animal will have a higher glycoprotein content, while the cells from the Mojave Desert animal will have a higher lipoprotein content.The cells from the Mojave Desert animal will have a higher cholesterol concentration in the plasma membranes.Water moves via osmosis _________. a. throughout the cytoplasm b. from an area with a high concentration of other solutes to a lower one c. from an area with a high concentration of water to one of lower concentration d. from an area with a low concentration of water to higher concentrationfrom an area with a high concentration of water to one of lower concentrationThe principal force driving movement in diffusion is the __________. a. temperature b. particle size c. concentration gradient d. membrane surface areaconcentration gradientWhat problem is faced by organisms that live in fresh water? a. Their bodies tend to take in too much water. b. They have no way of controlling their tonicity. c. Only salt water poses problems for animals that live in it. d. Their bodies tend to lose too much water to their environment.Their bodies tend to take in too much water.In which situation would passive transport not use a transport protein for entry into a cell? a. water flowing into a hypertonic environment b. glucose being absorbed from the blood c. an ion flowing into a nerve cell to create an electrical potential d. oxygen moving into a cell after oxygen deprivationoxygen moving into a cell after oxygen deprivationActive transport must function continuously because __________. a. plasma membranes wear out b. not all membranes are amphiphilic c. facilitated transport opposes active transport d. diffusion is constantly moving solutes in opposite directionsdiffusion is constantly moving solutes in opposite directionsHow does the sodium-potassium pump make the interior of the cell negatively charged? a. by expelling anions b. by pulling in anions c. by expelling more cations than are taken in d. by taking in and expelling an equal number of cationsby expelling more cations than are taken inWhat is the combination of an electrical gradient and a concentration gradient called? a. potential gradient b. electrical potential c. concentration potential d. electrochemical gradientelectrochemical gradientWhat happens to the membrane of a vesicle after exocytosis? a. It leaves the cell. b. It is disassembled by the cell. c. It fuses with and becomes part of the plasma membrane. d. It is used again in another exocytosis event.It fuses with and becomes part of the plasma membrane.Which transport mechanism can bring whole cells into a cell? a. pinocytosis b. phagocytosis c. facilitated transport d. primary active transportphagocytosisIn what important way does receptor-mediated endocytosis differ from phagocytosis? a. It transports only small amounts of fluid. b. It does not involve the pinching off of membrane. c. It brings in only a specifically targeted substance. d. It brings substances into the cell, while phagocytosis removes substances.It brings in only a specifically targeted substance.Many viruses enter host cells through receptor-mediated endocytosis. What is an advantage of this entry strategy? a. The virus directly enters the cytoplasm of the cell. b. The virus is protected from recognition by white blood cells. c. The virus only enters its target host cell type. d. The virus can directly inject its genome into the cell's nucleus.The virus only enters its target host cell type.Which of the following organelles relies on exocytosis to complete its function? a. Golgi apparatus b. vacuole c. mitochondria d. endoplasmic reticulumGolgi apparatusImagine a cell can perform exocytosis, but only minimal endocytosis. What would happen to the cell? a. The cell would secrete all its intracellular proteins. b. The plasma membrane would increase in size over time. c. The cell would stop expressing integral receptor proteins in its plasma membrane. d. The cell would lyse.The plasma membrane would increase in size over time.Why is it advantageous for the cell membrane to be fluid in nature?The fluid characteristic of the cell membrane allows greater flexibility to the cell than it would if the membrane were rigid. It also allows the motion of membrane components, required for some types of membrane transport.Why do phospholipids tend to spontaneously orient themselves into something resembling a membrane?The hydrophobic, nonpolar regions must align with each other in order for the structure to have minimal potential energy and, consequently, higher stability. The fatty acid tails of the phospholipids cannot mix with water, but the phosphate "head" of the molecule can. Thus, the head orients to water, and the tail to other lipids.How can a cell use an extracellular peripheral protein as the receptor to transmit a signal into the cell?Peripheral proteins can bind to other molecules in the extracellular space. However, they cannot directly transmit a signal to the inside of the cell since they do not have a transmembrane domain (region that goes through the plasma membrane to the inside of the cell). They must associate with integral membrane proteins in order to pass the signal to the inside of the cell.Discuss why the following affect the rate of diffusion: molecular size, temperature, solution density, and the distance that must be traveled.Heavy molecules move more slowly than lighter ones. It takes more energy in the medium to move them along. Increasing or decreasing temperature increases or decreases the energy in the medium, affecting molecular movement. The denser a solution is, the harder it is for molecules to move through it, causing diffusion to slow down due to friction. Living cells require a steady supply of nutrients and a steady rate of waste removal. If the distance these substances need to travel is too great, diffusion cannot move nutrients and waste materials efficiently to sustain life.Why does water move through a membrane?Water moves through a membrane in osmosis because there is a concentration gradient across the membrane of solute and solvent. The solute cannot effectively move to balance the concentration on both sides of the membrane, so water moves to achieve this balance.Both of the regular intravenous solutions administered in medicine, normal saline and lactated Ringer's solution, are isotonic. Why is this important?Injection of isotonic solutions ensures that there will be no perturbation of the osmotic balance, and no water taken from tissues or added to them from the blood.Describe two ways that decreasing temperature would affect the rate of diffusion of molecules across a cell's plasma membrane.Decreasing temperature will decrease the kinetic energy in the system. A lower temperature means less energy in the molecules, so they will move at a slower speed. Lowering temperature also decreases the kinetic energy of the molecules in the plasma membrane, compressing them together. This increases the density of the plasma membrane, which slows diffusion into the cell.A cell develops a mutation in its potassium channels that prevents the ions from leaving the cell. If the cell's aquaporins are still active, what will happen to the cell? Be sure to describe the tonicity and osmolarity of the cell.Without functional potassium channels, the potassium ions that are pumped into the cell will accumulate. This increases the osmolarity inside the cell, creating a hypotonic solution. Since the plasma membrane is still selectively permeable to water by the aquaporins, water will flow into the cell. If the potassium concentration is high enough, enough water will eventually flow into the cell to lyse it.Where does the cell get energy for active transport processes?The cell harvests energy from ATP produced by its own metabolism to power active transport processes, such as the activity of pumps.How does the sodium-potassium pump contribute to the net negative charge of the interior of the cell?The sodium-potassium pump forces out three (positive) Na+ ions for every two (positive) K+ ions it pumps in, thus the cell loses a positive charge at every cycle of the pump.Glucose from digested food enters intestinal epithelial cells by active transport. Why would intestinal cells use active transport when most body cells use facilitated diffusion?Intestinal epithelial cells use active transport to fulfill their specific role as the cells that transfer glucose from the digested food to the bloodstream. Intestinal cells are exposed to an environment with fluctuating glucose levels. Immediately after eating, glucose in the gut lumen will be high, and could accumulate in intestinal cells by diffusion. However, when the gut lumen is empty, glucose levels are higher in the intestinal cells. If glucose moved by facilitated diffusion, this would cause glucose to flow back out of the intestinal cells and into the gut. Active transport proteins ensure that glucose moves into the intestinal cells, and cannot move back into the gut. It also ensures that glucose transport continues to occur even if high levels of glucose are already present in the intestinal cells. This maximizes the amount of energy the body can harvest from food.The sodium/calcium exchanger (NCX) transports sodium into and calcium out of cardiac muscle cells. Describe why this transporter is classified as secondary active transport.The NCX moves sodium down its electrochemical gradient into the cell. Since sodium's electrochemical gradient is created by the Na+/K+ pump, a transport pump that requires ATP hydrolysis to establish the gradient, the NCX is a secondary active transport process.Why is it important that there are different types of proteins in plasma membranes for the transport of materials into and out of a cell?The proteins allow a cell to select what compound will be transported, meeting the needs of the cell and not bringing in anything else.Why do ions have a difficult time getting through plasma membranes despite their small size?Ions are charged, and consequently, they are hydrophilic and cannot associate with the lipid portion of the membrane. Ions must be transported by carrier proteins or ion channelswhich of the following is surrounded by two phospholipid bilayersnucleoplasmPeroxisomes got their name because hydrogen peroxide is: a. used in their detoxification reactions b. produced during their oxidation reactions c. incorporated into their membranes d. a cofactor for the organelles' enzymesproduced during their oxidation reactions

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