Microbiology - Chapter 4
A glycoprotein
is a type of peripheral protein above that can be used as a receptor or in enzymatic functions.
The DNA found in most bacterial cells
is circular in structure.
Which drawing in Figure 4.1 is streptococci?
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In the figure, which diagram of a cell wall contains teichoic acids?
A
Which of the following scenarios is an example of bacterial motility?
A bacterium moving towards a food source
Which type of solution would cause a bacterium with a weak or damaged cell wall to burst as water moves into the cell?
A hypotonic solution has a lower solute concentration than the inside of the cell; therefore, water would move into the cell, which might cause a weak or damaged cell to rupture.
Which of the following is NOT part of the passive transport process?
ATP
Why is ATP necessary for active transport?
ATP provides energy to transfer material against its concentration gradient.
By which of the following mechanisms can a cell transport a substance from a lower to a higher concentration?
Active transport
Which type of active transport protein uses one protein to pump two different molecules?
Antiport and Symport
In Figure 4.3, which diagram of a cell wall is a gram-negative cell wall?
B
In the figure, which diagram of a cell wall contains porins?
B
In the figure, which diagram of a cell wall is decolorized by alcohol?
B
In the figure, which diagram of a cell wall is resistant to many antibiotics (e.g., penicillin)?
B
In the figure, which diagram of a cell wall possesses lipid A/endotoxin responsible for symptoms associated with infection?
B
Which of the following structures is NOT found in some prokaryotic cells?
Cilium
In the figure, which diagram of a cell wall has a structure that protects against osmotic lysis?
Both A and B
Which molecule shown in the animation, the square or the circle, is moving against its concentration gradient?
Both the circle and the square
How does water enter and exit a cell?
By simple diffusion or by use of an integral transport protein
Which structure acts like an "invisibility cloak" and protects bacteria from being phagocytized?
Capsule
Which of the following is NOT found or observed to occur in both mitochondria and prokaryotes?
Cell wall
Which of the following is found in the cytoplasm of prokaryotic cells but is ABSENT from the cytoplasm of eukaryotic cells?
DNA
Which of the following statements is true?
Endospores allow a cell to survive environmental changes by producing a dormant period with no growth.
Actually, there is much more to the cell wall than appears in Figure 4.6. There are two fundamental types of bacterial cell walls: Gram-positive cell walls, and Gram-negative cell walls. These two cell wall-types can be differentiated by using a Gram stain, which results in Gram-positive bacteria staining a deep purple, and Gram-negative organisms staining a pink or red. This difference in cell wall structure results in more than just color differences when bacteria are Gram-stained, however. Knowledge of the cell wall type can enable prediction of other characteristics such as sensitivity to certain antibiotics, production of toxins, and susceptibility to disruption by different environmental agents. Understanding such differences begins with knowledge of the structural differences between these two cell wall types.
External Environment - capsule, cell wall, plasma membrane - Cytoplasm
There are some structures that are common to all prokaryotic cells, and others that are only found in some bacterial species or strains.
F. ribosomesG. plasma membraneH. cytoplasmI. nucleoid
T/F: Cells placed in a hypotonic solution tend to lose water due to osmotic pressure.
False
T/F: Endospores are a reproductive structure.
False
T/F: Many enzymes in both prokaryotic and eukaryotic cells are compartmentalized within organelles.
False
What structural part of a bacterial flagellum is composed of flagellin?
Filament
Which of the following statements about bacterial flagella is true?
Flagella can rotate 360 degrees.
Which one of the following organisms has a cell wall?
Fungi
How are Gram-positive and Gram-negative flagella different?
Gram-positive flagellum has only two rings in its basal body; Gram-negatives each have four.
You have isolated a motile, gram-positive cell with no visible nucleus. You can safely assume that the cell
Has a cell wall
Which statement regarding the structure or function of ribosomes is correct?
In eukaryotes, the ribosomes found in chloroplasts and mitochondria are 70S ribosomes, which are similar in size to prokaryotic ribosomes.
Which of the following statements accurately describes specific bacterial cell walls?
In gram-negative bacteria, the thin layer of peptidoglycan is surrounded by an outer membrane made of phospholipids, lipopolysaccharides, and proteins. The difference in peptidoglycan thickness and the outer membrane distinguishes gram-positive from gram-negative bacteria.
Which of the following molecules would be blocked by a cell membrane?
Ions
Which of the following statements is correct about passive diffusion?
It involves movement of molecules down a concentration gradient and may require a transport protein. Submit
What is a hallmark of passive transport across cell membranes?
It occurs along an electrochemical gradient, and may involve the use of transport proteins.
Which of the following statements regarding active transport is false?
It powers the diffusion of water across the cell membrane.
A strain of Streptococcus pneumoniae is no longer able to synthesize its capsular polysaccharide. What is a likely outcome?
It will be readily phagocytized upon entering the host. The presence of a polysaccharide capsule is a well-known virulence factor of Streptococcus pneumoniae. Encapsulated strains typically produce smooth glistening, mucoid-appearing colonies. Non-encapsulated strains produce flat, dry colonies. Inoculating mice with these two strains readily demonstrates the virulence of the encapsulated strains, and the lack of virulence of the non-encapsulated strains.
A strain of Neisseria gonorrhoeae has been genetically altered and can no longer produce fimbriae. What is a likely outcome?
It will be unable to adhere to host tissue and establish infection. Fimbriae are an important virulence factor of Neisseria gonorroheae. These delicate structures support adhesins which enable Neisseria gonorrohoeae strains to adhere to the tissues of a host and establish infection.
Which of the following types of bacterial cells would have flagella located at only one end of the cell?
Lophotrichous and monotrichous
Which of the following organelles breaks down worn-out organelles?
Lysosomes contain digestive enzymes and break down worn-out organelles.
Which of the following types of bacterial cells would have only a single flagellum?
Monotrichous
Taxis is
Movement toward or away from a stimulus.
Where is the genetic information of the cell stored?
Nucleus
Which of the following terms refers to a bacterium moving towards a light source?
Positive phototaxis
Which of the following would not move freely across the cytoplasmic membrane?
Positively charged hydrogen ions
Which of the following facts does NOT provide evidence for the endosymbiotic theory?
Prokaryotes contain peptidoglycan in their cell walls. This is not evidence supporting the endosymbiotic theory; rather, it highlights a difference between bacteria and mitochondria and chloroplasts.
This activity requires that you sort cell structures according to whether they are found in prokaryotic cells or eukaryotic cells.
Prokaryotic cellsCircular chromosome, not enclosed within a nuclear envelopePeptidoglycan-containing cell wall70s ribosomesFlagella that rotate, composed of flagellinEukaryotic cellsLinear chromosomes enclosed within a nuclear envelopeCellulose or chitin-containing cell wallFlagella that wave, composed of microtubulesGolgi apparatusLysosomesMitochondria80s ribosomesEndoplasmic reticulum
One of the ways smooth endoplasmic reticulum (ER) differs from rough endoplasmic reticulum is that rough ER is covered by
Ribosomes dock on the rough ER, and proteins are completed inside the rough ER.
The basal body is comprised of which structural component(s) of flagella?
Rods and rings
Drag the labels onto the flowchart to trace the movement of proteins through the endomembrane system and out of the cell.
Rough ER> Vesicle from ER>Golgi apparatus>Vesicle from Golgi>Plasma Membrane
How is simple diffusion different from other types of passive transport?
Simple diffusion does not require a permease
How do spirochetes and spirilla differ?
Spirilla have an external flagella but spirochetes have axial filaments.
T/F: Small, hydrophobic molecules pass through a cell membrane most easily by diffusion.
True
T/F: Spheroplasts, protoplasts, and mycoplasms are bacterial cells without cell walls.
True
Which type of active transport protein moves two molecules into the cell at the same time?
Symport
What carries instructions for making proteins from the nucleus into the cytoplasm?
The "m" in mRNA stands for "messenger"; mRNA is the messenger that carries genetic instructions from the nucleus to the cytoplasm.
What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane?
The cell will lose its interior water, causing it to shrivel up and possibly die.
What will happen if a bacterial cell is pretreated with a lysozyme solution, then placed in distilled water?
The cell will undergo osmotic lysis.
Why is no energy required in passive transport?
The concentration gradient drives the movement.
What structure acts as a selective barrier, regulating the traffic of materials into and out of the cell?
The plasma membrane surrounds the cell and regulates the movement of materials into and out of the cell.
Why are receptors on the cell surface necessary for bacterial movement?
The receptors sense the stimulus and send signals to the flagella.
Which of the following statements about gram-negative cell walls is FALSE?
They are sensitive to penicillin.
What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass?
They have both hydrophilic and hydrophobic regions.
Which of the following statements is INCORRECT regarding prokaryotic cells?
They lack a plasma membrane.
T/F: Antibiotics that target the cell wall are an effective treatment against many pathogenic bacteria.
True
T/F: If you observe rod-shaped red cells after the Gram stain, you can assume their cell walls contain endotoxin.
True
T/F: The cell walls of bacteria are responsible for the shape of the bacteria and the difference in the Gram stain reaction.
True
T/F: The internal structure of eukaryotic cilia and flagella are the same.
True
Which transport protein employs transporters that move molecules only in one direction?
Uniport and Symport
How is osmosis different from simple diffusion?
Water movement is driven by the concentration of solutes rather than its own concentration.
Which of the following statements best describes what happens when a bacterial cell is placed in a solution containing 5% NaCl?
Water will move out of the cell.
Which of the following is part of the endomembrane system?
Which of the following is part of the endomembrane system?
Functions of the glycocalyx include all of the following EXCEPT
binary fission
Which membrane transport mechanism requires ATP?
active transport
Nonspecific permeases
allow a variety of molecules to cross the cytoplasmic membrane.
The rings
anchor the flagellum to the cell membrane.
Hydrophobic molecules move across a membrane
by passive transport directly across the membrane.
Pathogenic bacteria
can be identified and classified by differences in their flagellar proteins.
Which of the following are NOT energy reserves?
carboxysomes
Which of the following pairs is mismatched?
centrosome food storage
In bacteria, photosynthetic pigments are found in
chromatophores
A gram-positive bacterium suddenly acquires resistance to the antibiotic methicillin. This trait most likely occurred due to acquisition of new genetic information through
conjugation
Which of the following is NOT a typical characteristic of most bacterial plasma membranes?
contains cholesterol
Which of the following is NOT characteristic of the glycocalyx found in bacteria?
creates a slimy, slippery coating that prevents bacteria from attaching to surfaces
The structural framework in a cell is the
cytoskeleton. The cytoskeleton is the structural framework in a cell ("cyto" refers to cell and "skeleton" refers to a structural framework).
The immune response of a host against an invading bacterium is often triggered by surface components on the bacterium that are recognized as "non-self" or "foreign" by the host. These non-self components, often protein or polysaccharide in nature, are referred to as antigens. The host responds to these antigens by making antibodies that will react with invading bacteria and mark them or tag them for destruction by phagocytes.
fimbriae, cell wall, flagella, capsule
You are observing a Gram stain of spherical-shaped microorganisms that are linked in a chain and stain purple. How would you describe these bacteria using the correct terminology for the cell shape and arrangement? a) gram-positive tetrads b) gram-positive coccobacilli c) gram-positive streptococci d) gram-negative staphylococci
gram-positive streptococci
Which of the following is a characteristic of the glycocalyx found in bacteria?
if firmly attached, contributes to bacterial virulence; viscous coating surrounding the cell made of polysaccharide, polypeptide, or both;a structure that can be visualized using an acidic negative stain and a basic counterstain
An important characteristic of antibacterial drugs is their selective toxicity. If antibacterial drugs were not selectively toxic, then they would kill or interfere with the hosts' cells as well as bacterial cells. Examining cellular differences between bacterial (prokaryotic) cells and host (eukaryotic) cells suggests strategies to achieve selective toxicity. We can capitalize on these differences and take advantage of them in the design of antibacterial drugs
inhibition of peptidoglycan synthesisinhibition of fimbriae synthesisinterfering with translation at 70s ribosomes
Each of the following statements concerning the gram-positive cell wall is true EXCEPT
it protects the cell in a hypertonic environment.
Which of the following terms best describes the cell in the figure?
lophotrichous flagella
Bacteria are a commonly used organism for studies of genetic material in the research laboratory. The nucleic acids must first be isolated from the cells for these studies. Which of the following would most likely be used to lyse gram-positive bacterial cells for nucleic acid isolation?
lysozyme
Amino acids and fatty acids are oxidized in which of the following organelles?
peroxisome
Where in a cell is ATP made?
mitochondria
Which of the following organelles most closely resembles a prokaryotic cell?
mitochondrion
Once equilibrium is reached,
molecules move, but there is no net movement in a particular direction.
Which drawing in Figure 4.1 is a tetrad?
oo oo
Antibiotics that target cell wall synthesis ultimately cause bacterial cell death as a result of
osmotic lysis.
Fimbriae and pili differ in that
pili are used for transfer of DNA and motility.
In a hypertonic solution, a bacterial cell will typically
plasmolyze.
The difference between simple diffusion and facilitated diffusion is that facilitated diffusion
requires transporter proteins.
Which one of the following pairs is mismatched?
ribosomes - carbon storage
As a bacterium approaches a food source, one would expect
runs to become more frequent.
Where are lipids made in the cell?
smooth endoplasmic reticulum (ER)
Axial filaments are found on
spirochetes
Tumbles occur when
the flagella rotate clockwise.
Peritrichous bacteria make a run when
the flagella turn counterclockwise and become bundled.
Where are phospholipids most likely found in a prokaryotic cell?
the plasma membrane
Where are phospholipids most likely found in a eukaryotic cell?
the plasma membrane, around organelles, and surrounding flagella
Integral proteins are mostly involved in
transport function
Which of the following eukaryotic organelles is correctly matched with its function?
vacuole--storage of materials Submit
A positively charged sodium ion
would require the use of integral protein channels to pass through a cell membrane.
Which drawing in the figure possesses an axial filament?
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