BIO205 Chapter 5
What is the nucleoid of a bacterial cell? A. The region within the cytoplasm where the loops of the DNA chromosome are supercoiled B. A round, membrane-enclosed compartment holding the cell's DNA C. A dense region of the cell where ribosome assembly occurs D. The space that exists between the two membranes of a Gram-negative cell
A. The region within the cytoplasm where the loops of the DNA chromosome are supercoiled
Which of the following tasks would be a possible function of a bacterial pilus?Choose one or more: A.Pili are hollow so they can form a tube that connects the cytoplasm of two cells and allow for the transfer of genetic material between them. B.Pili rotate to allow the cell to propel itself forward in an aqueous environment. C.Pili allow cells to adhere to surfaces so that they do not get washed away from a favorable environment. D.Pili are able to collect light used for photosynthesis. E.Pili can store energy that the cell can use at a later time.
A.Pili are hollow so they can form a tube that connects the cytoplasm of two cells and allow for the transfer of genetic material between them. C.Pili allow cells to adhere to surfaces so that they do not get washed away from a favorable environment.
Which of the following statements correctly describes the structure of the bacterial chromosome? A. A single circular loop of DNA (equal to or slightly smaller than the circumference of the cell itself) is loosely looped within the cytoplasm. B. A single circular chromosome is much greater in circumference than the cell itself, so it is twisted back on itself and coiled up within the cytoplasm. C. Multiple intertwined circles of DNA are chained within the cytoplasm of the cell. D. Multiple linear pieces of DNA are held together within the nucleoid region by DNA-binding proteins.
B. A single circular chromosome is much greater in circumference than the cell itself, so it is twisted back on itself and coiled up within the cytoplasm.
What part of the bacterial cell does methicillin target? A. Methicillin inhibits the process of transcription by binding to bacterial RNA polymerase enzymes. B. Methicillin inhibits peptidoglycan synthesis in the bacterial cell wall. C. Methicillin inhibits protein synthesis by binding to the bacterial ribosomes. D. Methicillin inhibits DNA organization by binding to DNA gyrase.
B. Methicillin inhibits peptidoglycan synthesis in the bacterial cell wall.
What is a permease, and what is its function? A. A permease is a type of toxin that can freely cross the cell membrane to bind to its intracellular target. B. A permease is a nutrient that is able to passively diffuse through the cell membrane. C. A permease is a protein that transports molecules across plasma membranes. D. A permease is a toxin produced by certain pathogens which disrupts host cell membranes.
C. A permease is a protein that transports molecules across plasma membranes.
Which of the following is NOT a function of membrane-embedded proteins? A. Membrane-embedded proteins can form the base of structures that extend out of the cell (such as flagella and pili). B. Membrane-embedded proteins can import or export specific molecules through the membrane. C. Membrane-embedded proteins can store important inheritable information that is needed by the cell. D. Membrane-embedded proteins can serve as receptors that detect specific environmental conditions.
C. Membrane-embedded proteins can store important inheritable information that is needed by the cell.
The name of the bacterial species that caused Jennifer's infection is Staphylococcus aureus. Based on this information, what shape would you expect the cell to be? A. Comma-shaped B. Elongated ovals C. Spheres D. Spirals
C. Spheres
What is chemotaxis? A. The ability to move nutrients across the cell membrane B. The ability to hide within another type of cell C. The ability to bind to a surface so as not to be moved away from a favorable environment D. The ability to move toward or away from a chemical stimulus
D. The ability to move toward or away from a chemical stimulus
Which of the following is the subject of the theory of endosymbiosis? A. The phenomenon observed with pathogens such as the influenza virus and Mycobacterium tuberculosis, which are able to trick host cells into endocytosing them so they can live inside these cells B. The idea that internal parasites can lose cellular structures such as cell walls over time because they do not need them if they live within host cells C. The way the cell maintains a flow of nutrients into the cell through the process of endocytosis and eliminates waste through the process of exocytosis D. The process by which organelles such as chloroplasts and mitochondria arose from free-living bacterial cells entering into mutualistic relationships with larger cells early in the history of living cells
D. The process by which organelles such as chloroplasts and mitochondria arose from free-living bacterial cells entering into mutualistic relationships with larger cells early in the history of living cells
Which of the following is true of bacterial DNA replication? a. A single replisome replicates the entire genome. b. In growing cells, DNA replication initiates once the cytoplasmic volume reaches a threshold level. c. DNA replication is compatible with transcription, and both can occur at the same time. d. There are multiple origins of replication to help speed up the process of replication.
DNA replication is compatible with transcription, and both can occur at the same time. FEEDBACK: In growing bacterial cells, DNA is synthesized continuously by two replisomes that move in opposite directions from a single origin of replication. This happens while transcription and translation are also occurring. See section 5.4 in your text for more information.
eukaryotes
DNA surrounded by nuclear envelope Linear chromosome found in a true nucleus surrounded by a nuclear membrane. Cell growth and DNA replication occur at specific times in the cell cycle prior to cell division. DNA associated with histones Membrane enclosed organelles Cells walls, if they have them are very simple Division is usually by Mitosis. Much larger cells
simple diffusion
Diffusion that doesn't involve a direct input of energy or assistance by carrier proteins.
active transport
Energy-requiring process that moves material across a cell membrane against a concentration difference
flagella components(3)
Filament (external): the part you see that is composed of the protein flagellin. Hook: connects the filament to the cell surface. Basal Body: anchors the flagellum to the cell wall and cytoplasmic membrane.
Flagella
Filamentous protein appendage. Used primarily for motility. It is a long filamentous appendage. Prokaryotic flagella rotate to push the cell. Motile bacteria exhibit taxis: positive taxis is movement toward an attractant, and negative taxis is movement away from a repellent
facilitated diffusion
Is like simple diffusion except the molecule or particle of interest is too big to fit through the membrane pores so it needs a helper
Which of the following is evidence for the bacterial origin of mitochondria? a. Mitochondria are surrounded by a single membrane. b. Mitochondria contain their own ribosomes. c. Mitochondria contain a circular chromosome. d. There is only one mitochondria per eukaryotic cell.
Mitochondria contain a circular chromosome FEEDBACK: Mitochondria are surrounded by a double membrane, and there may be multiple mitochondria per cell. The presence of ribosomes indicates that mitochondria were once free-living, but eukaryotic cells also contain ribosomes. Bacterial cells have circular chromosomes similar to what is observed in mitochondria-this is the strongest piece of evidence listed. See section 5.6 in your text for more information.
Prokaryote characteristics
No nuclear membrane (envelope that encloses DNA). DNA is single, circular chromosome found in nucleoid of cytoplasm; growing bacteria replicate DNA continuously. DNA is not associated with Eukaryotic Histones (chromosomal protein). Lack membrane enclosed organelles. Cell wall contains complex polysaccharide, peptidoglycan. Divide by binary fission.
Which component of lipopolysaccharide (LPS) helps bacterial cells avoid phagocytosis? a. peptidoglycan b. lipid A c. core polysaccharide d. O antigen
O antigen FEEDBACK: Peptidoglycan is not part of the LPS. The lipid A part of LPS is embedded in the outer membrane, and the core polysaccharide connects lipid A to the O antigen, a very long polysaccharide chain that helps pathogens resist phagocytosis. The O antigen is also known as O polysaccharide. See section 5.3 in your text for more information.
How does the bacterial cell wall differ from the cell membrane? a. Only the cell wall is composed of organic molecules. b. Only the cell membrane is impermeable to ions. c. Only the cell wall is external to the cytoplasm. d. Only the cell membrane is unique to bacteria.
Only the cell membrane is impermeable to ions. FEEDBACK: All cells are surrounded by a cell membrane composed of organic lipids, and the lipids make the membrane impermeable to charged molecules, such as ions. Bacterial cell walls, which are porous, are composed of the organic molecule peptidoglycan. See section 5.3 in your text for more information.
Which of the following is NOT a function of the cell membrane? a. energy storage b. structural support c. transport d. RNA production
RNA production FEEDBACK: The cell membrane phospholipids and proteins have many functions including energy storage, structural support, transport into and out of the cell, and cell communication. RNA production is not one of the cell membrane functions and instead happens in the cytoplasm. See section 5.2 in your text for more information.
passive transport
Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient
Which of the following is NOT necessarily a component of bacteria that stains Gram-positive? a. cell membrane b. peptidoglycan c. teichoic acids d. S-layer
S-layer FEEDBACK: All cells are surrounded by a cell membrane. The thick peptidoglycan cell walls and negatively charged teichoic acids of Gram-positive bacteria are what help retain the Gram stain. While an S-layer is frequently found in Gram-positive bacteria, it is not obligatory. See section 5.3 in your text for more information.
Glycocalyx
The glycocalyx (capsule, slime layer, or extracellular polysaccharide) is a gelatinous polysaccharide and/or polypeptide covering. Sugar coat that is therefore sticky. Its function is for protection and attachment.
endosymbiosis theory
The mitochondria of eukaryotes evolved from an aerobic bacterium (probably related to the rickettsias) living within an archaeal host cell. The chloroplasts of red algae, green algae, and plants evolved from an endosymbiotic cyanobacterium living within a mitochondria-containing eukaryotic host cell.
solute pumping(Na/K)
The sodium-potassium pump is a solute pump that requires energy by the cell because it has to move against its concentration gradient to get inside the cell. If it were in the normal direction, substances would flow by natural simple diffusion. The sodium-potassium pump simultaneously carries Sodium ions OUT of and Potassium ions INTO the cell.
Which of the following statements about bacterial flagella is correct? a. They move in a whip-like fashion powered by ATP. b. They move in a whip-like fashion powered by the proton motive force. c. They move in a rotary fashion powered by ATP. d. They move in a rotary fashion powered by the proton motive force.
They move in a rotary fashion powered by the proton motive force FEEDBACK: Bacterial flagella spin like a propeller and are powered by hydrogen ions moving through the motor. Eukaryotic flagella are powered by ATP and move in a whip-like fashion. See section 5.5 in your text for more information.
Most bacteria have _____. a. a single circular chromosome in the cytoplasm. b. a single circular chromosome in the nucleus. c. multiple linear chromosomes in the cytoplasm. d. multiple linear chromosomes in the nucleus.
a single circular chromosome in the cytoplasm. FEEDBACK: While a few bacteria contain linear chromosomes, most contain a single circular chromosome located in the cytoplasm. Most eukaryotes contain multiple linear chromosomes found within a nucleus. See section 5.4 in your text for more information.
glycocalyx types(2)
a. CAPSULE: distinct and gel like. Firmly attached to cell wall. Capsules may protect pathogens from phagocytosis. Capsules enable adherence to surfaces, prevent desiccation, and may provide nutrients. b. SLIME LAYER: unorganized and loosely attached to the cell wall.
axial filaments
also called Endoflagella. They are bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell. They function in movement, corkscrew movement
Cell membrane proteins may directly aid in ________________. a. DNA replication b. DNA repair c. RNA production d. cell communication
cell communication FEEDBACK: The enzymes involved in DNA replication and repair and RNA replication are found in the cytoplasm. Proteins embedded in the membrane may be involved in sensing signals from other cells. See section 5.2 in your text for more information.
Cells that elongate their cell walls prior to septation and septate in parallel planes will form a. chains of rods (bacilli). b. tetrads of rod (bacilli). c. chains of spheres (cocci). d. tetrads of spheres (cocci).
chains of rods - bacilli FEEDBACK: Rod-shaped cells grow their cell walls prior to septation; cocci expand their cell walls during septation. The plane of division influences the geometry of collections of cells. Chains form when septation occurs in parallel planes while tetrads form when septation occurs at precise right angles to the previous division. See section 5.4 in your text for more information.
A mutant strain of this bacterium that lacked the thin protein fibrils shown here would likely be unable to do what? resist desiccation exhibit swimming motility colonize host cells transfer DNA to another cell via conjugation bind to and transport nutrients
colonize host cells
One function of the Golgi complex is a. harnessing the proton motive force to generate ATP. b. directing proteins to appropriate cellular locations. c. providing an acidic environment for macromolecule digestion. d. providing structure to help determine cell shape.
directing proteins to appropriate cellular locations. FEEDBACK: The Golgi complex can tag proteins with various sugars that serve as "zip codes" to direct proteins to appropriate cellular locations, such as the lysosome. A proton motive force is used to generate ATP in the mitochondria and chloroplasts; lysosomes provide an acidic environment for digestion; and the cytoskeleton provides structure that helps determine cell shape. See section 5.6 in your text for more information.
Which organelle is continuous with the outer nuclear membrane? a. endoplasmic reticulum b. endosome c. Golgi complex d. lysosome
endoplasmic reticulum FEEDBACK: The nuclear membrane is a double membrane, meaning it contains two phospholipid bilayers. The outer bilayer is continuous with the endoplasmic reticulum. See section 5.6 in your text for more information.
Proteins that transport only one kind of molecule down that molecule's concentration gradient are involved in ________________. a. passive transport b. active transport c. facilitated diffusion d. coupled transport
facilitated diffusion FEEDBACK: Since the protein only transports one kind of molecule, the answer is not coupled transport. Passive transport does not use proteins; it involves diffusion directly across the lipid bilayer. Active transport uses energy to move molecules against their concentration gradient. The only answer that works here is facilitated diffusion-the movement of molecules down their concentration gradient (diffusion) facilitated by a transmembrane protein. See section 5.2 in your text for more information.
The periplasm is found in ________________. a. Gram-positive bacteria b. Gram-negative bacteria c. archaea d. eukaryotic microbes
gram-negative bacteria FEEDBACK: The periplasm is the space between the outer and inner membranes and is only found in Gram-negative bacteria. See section 5.1 in your text for more information.
Siderophores are used to obtain which nutrient from the environment? a. ATP b. glucose c. iron d. potassium
iron FEEDBACK: Iron, an essential nutrient, is often in short supply in the environment. Siderophores bind extracellular iron with high affinity and help transport it into the cell via ABC transporters. See section 5.2 in your text for more information.
The bacterial cell wall is composed of ________________. a. peptidoglycan b. phospholipids c. chitin d. cellulose
peptidoglycan FEEDBACK: Bacterial cell walls contain peptidoglycan. Phospholipids are found in cell membranes. The cell wall is distinct from the cell membrane. Cellulose is a component of plant cell walls, and chitin is a component of fungal cell walls. See section 5.1 in your text for more information.
The major organic component (by total weight) of a bacterial cell is ________________. a. DNA b. RNA c. protein d. water
protein FEEDBACK: While water makes up 70% of the cell by weight, water is not organic. The bulk of the organic component is protein. See section 5.1 in your text, specifically table 5.2, for more information.
Which structure aids bacterial adherence to a substrate? a. flagellum b. septum c. stalk d. thylakoid
stalk FEEDBACK: Stalks and pili mediate bacterial adherence. Flagella aid motility, thylakoids are intracellular membranes for photosynthesis, and the septum is a partition that separates a bacterial cell into two new daughter cells. See section 5.5 in your text for more information.
Which of the following structures is only found in some bacterial species? a. storage granules b. nucleoid c. cell membrane d. ribosomes
storage granules FEEDBACK: Only some bacteria store energy in storage granules composed of glycogen or other polymers. All bacteria have a nucleoid, cell membrane, and ribosomes. See 5.5 section in your text for more information.
Lipopolysaccharides are part of ________________. a. the outer membrane b. the inner membrane c. the cell wall d. the cell membrane
the outer membrane FEEDBACK: Lipopolysaccharides are part of the outer membrane of Gram-negative bacteria and project into the extracellular environment. Lipopolysaccharides confer defensive and toxic properties to many Gram-negative pathogens. See section 5.1 in your text for more information.
pilli
used primarily for attachment. Similar in structure to flagella. They are also called FIMBRIAE (short and many; enable cells to adhere to surfaces including other cells.) Pilli are longer and usually no more than one or two are seen on the surface. They help join bacterial cells in preparation fro the transfer of DNA from one cell to another like in Conjugation.
cell membrane protein functions
· Structural Support · Detecting environmental signals · Secreting virulence factors and communication · Transport across the cell membrane · Energy Storage and transfer
evidence of endosymbiotic theory
• Both mitochondria and chloroplasts can arise only from preexisting mitochondria and chloroplasts. They cannot be formed in a cell that lacks them because nuclear genes encode only some of the proteins of which they are made. • Both mitochondria and chloroplasts have their own genome, and it resembles that of bacteria not that of the nuclear genome. • Both mitochondria and chloroplasts have their own protein-synthesizing machinery, and it more closely resembles that of bacteria than that found in the cytoplasm of eukaryotes (antibiotics + inhibitors that affect bacteria also affect mitochondria and chloroplasts)
