Cell Structure [2] Flashcards
What is lipid A?
It is the lipid which attaches to the core section of the polysaccharide in a lipid polysaccharide.
Which of the following molecules is shared by both Gram-positive and Gram-negative organisms? A N-acetylmuramic acid B lipopolysaccharide C lipoteichoic acid D lipid A
A
Amoxicillin is an antibiotic that inhibits the formation of peptide cross-links. Amoxicillin, therefore, would most likely inhibit the growth of __________.
A only Gram positive organisms
B neither Gram-positive nor Gram-negative organisms
C both Gram-positive and Gram-negative organisms
D only Gram-negative organisms
C
Porins are present in ______________bacteria because, in these organisms, molecules entering the cell must pass through an extra layer of ___________.
A Gram-positive; membrane
B Gram-negative; membrane
C Gram-positive; peptidoglycan
D Gram-negative; peptidoglycan
E both Gram-negative and Gram-positive; membrane
B
While staining a mixed culture of Gram-positive and Gram-negative bacteria, switching the order of steps 2 and 3 would result in ______________________.
A a change in the Gram reaction; Gram-negative cells would appear purple while Gram-positive cells would appear pink.
B all bacteria appearing pink
C all bacteria appearing clear
D all bacteria appearing purple
B
Axial filaments are found on A staphylococci. B rod-shaped bacilli. C streptococci. D spirochetes.
D
Teichoic acid molecules in Gram-positive cell walls include phosphate groups. Therefore, they will \_\_\_\_\_\_\_\_\_\_. A bind other phosphate ions B bind negative ions like Cl– and SO42– C bind positive ions like Mg2+ and Ca2+ D not bind any ions
C
The presence of which of the components listed below would allow you to distinguish between a gram-positive or gram-negative cell wall? A teichoic acids -- gram-positive B N-acetylmuramic acid – gram-positive C N-acetylglucosamine – gram-negative D teiochic acids -- gram-negative
A
How are negative stains different from other types of stains?
A They stain the desired structure or specimen black.
B They stain the background, leaving the cells colorless.
C They stain more than one type of specimen.
B
What is the fundamental purpose of staining in light microscopy?
A To kill the specimen
B To increase the contrast and visibility of the specimen
C To make the specimen appear larger in the microscope
D To see the specimen without the aid of a microscope
B
Analysis of the second swab has confirmed that the causative organism is Streptococcus pyogenes, a gram-positive organism. Imagine that you are the technician looking at the Gram stain from Shelly’s culture. What would you expect to see as you look through the microscope?
A pink, rod-shaped organisms arranged in pairs
B purple, spherical-shaped organisms arranged in chainlike formations
C purple, spherical-shaped organisms arranged in grapelike clusters
D pink, spherical-shaped organisms arranged in chainlike formations
B
How will the prescribed penicillin kill S. pyogenes that is causing Shelly’s infection?
A Penicillin will attach to bacterial ribosomes and inhibit protein synthesis, which will lead to the death of S. pyogenes.
B Penicillin will interfere with peptidoglycan synthesis, ultimately weakening the cell wall and leading to cellular lysis.
C Penicillin will poke holes in the plasma membrane, weakening the cell and leading to cellular lysis.
D Penicillin will disrupt the outer membrane, leading to a loss of structural integrity and death of S. pyogenes.
B
Predict which type of organism would be more difficult to treat with antibiotics and why.
A gram-negative organisms – thinner peptidoglycan layer
B gram-positive organisms – thicker peptidoglycan layer
C gram-negative organisms – extra layer of LPS
D gram-positive organisms – no LPS laye
C
You have discovered a new coccoid-shaped microorganism with no nucleus, a rigid cell wall, and a diameter of 2 µm. Chemical tests reveal that its cell wall does NOT contain peptidoglycan. The new microorganism is
A most likely an archaeon.
B either a bacterium or an archaeon.
C most likely a eukaryote.
D most likely a bacterium.
A
The lipopolysaccharide (LPS) layer is found ONLY in the cell walls of A Archaea. B gram-negative Bacteria. C gram-positive Bacteria. D Eukarya.
B
An endotoxin is
A a toxin produced in the periplasm of most bacteria.
B the toxic portion of the LPS.
C a toxin known for its primary attack on the epidermis of mammals.
D a toxin produced within archaeal cells.
B
Some of the intestinal symptoms elicited by pathogens such as Salmonella, Shigella, and Escherichia are due to the presence of A S-layers. B peptidoglycan. C lipopolysaccharides. D pseudomurein.
C
Porins are channels in the outer membranes of gram-positive Bacteria.
A True
B False
B
Pathogenic bacteria that contain S-layers are protected against host defense mechanisms.
A True
B False
B
(S LAYERS, EXIST IN GRAM + AND -, AND ARCHAEA)
PROTECTIVE, ALLOW BINDING
Bacteria with type IV pili
A live in aquatic environments.
B have capsules that promote dehydration.
C likely exhibit twitching motility.
D possess tubular or stalk-like extensions of their cells.
C
Which of the following statements is FALSE?
A Fibriae are usually shorter than flagella and enable cells to adhere to surfaces, whereas pili are involved in genetic exchange.
B Fimbriae are generally shorter and more numerous than flagella.
C Pili serve as receptors and facilitate genetic exchange between prokaryotic cells.
D Fimbriae enable cells to stick to surfaces.
C
Explain why the presence of a capsule or slime layer would benefit a bacterial cell.
A These outer layers prevent water from entering the cell, causing rapid dehydration.
B These outer layers can help the immune system recognize foreign organisms.
C These outer layers can aid in attachment to solid surfaces.
D These outer layers can prevent added virulence during a bacterial infection.
C
Which of the following types of bacterial cells would have only a single flagellum? A Lophotrichous B Monotrichous C Lophotrichous and monotrichous D Amphitrichous E Peritrichous
B
Peritrichous bacteria make a run when
A the flagella turn counterclockwise and become bundled.
B the flagella turn clockwise and separate.
C the flagella turn counterclockwise and separate.
D the flagella turn clockwise and become bundled.
A
Which of the following types of bacterial cells would have flagella located at only one end of the cell? A Monotrichous B Lophotrichous and monotrichous C Lophotrichous D Amphitrichous E Monotrichous and amphitrichous F Peritrichous
B
Taxis is
A movement towards or away from a stimulus.
B caused by the undulating motion of a bacterium.
C another word for stimulus.
D another term for bacterial tumbling.
A
Which of the following terms refers to a bacterium moving towards a light source? A Positive chemotaxis B Positive phototaxis C Negative chemotaxis D Negative phototaxis
B
As a bacterium approaches a food source, one would expect
A runs to become more frequent.
B flagella to stop spinning.
C flagella to rotate clockwise more frequently.
D tumbles to become more frequent.
A
What structural part of a bacterial flagellum is composed of flagellin? A Basal body B Rod C Filament D Hook
C
How are Gram-positive and Gram-negative flagella different?
A Flagella are only found in Gram-negative bacteria.
B A Gram-positive flagellum has only two rings in its basal body; Gram-negatives each have four.
C A Gram-positive flagellum does not have a membrane covering its filament; A Gram-negative flagellum does.
D Each Gram-positive flagellum contains a hook; gram-negatives do not.
B
TWO RINGS FOR EACH PHOSPHOHEAD GROUP YOU PASS THROUGH
The rings
A are curved structures into which each filament inserts.
B are covered by a membrane.
C anchor the flagellum to the cell wall.
D are comprised of globular proteins called flagellin.
C
The basal body is comprised of which structural component(s) of flagella? A Rings B Hook C Rod D Rod and Rings E Filament F Rod and Hook
D
Pathogenic bacteria
A have a unique basal body structure.
B do not have flagella.
C are unique because they have a membrane covering the filament.
D can be identified and classified by differences in their flagellar proteins.
D
Cellular inclusions in prokaryotic cells serve to
A position cells in the appropriate environment for survival.
B store energy rich compounds.
C store energy rich compounds and position cells in the appropriate environment for survival.
D protect DNA.
C
Poly-β-hydroxybutyric acid (PHB) is a carbon- and energy-storing polymer.
A True
B False
A
A major function of prokaryotic gas vesicles is to
A store oxygen for aerobic growth when oxygen becomes depleted in the environment.
B serve as a reservoir for oxygen and carbon dioxide.
C confer buoyancy on cells by decreasing their density.
D keep the cell’s organelles separated during flagellar motion.
C
The membrane of a gas vesicle is composed of A carbohydrates. B various phospholipids. C both glycoproteins and phospholipids. D proteins.
D
Predict why dipicolinic acid is only found in endospores and not vegetative cells.
A It binds free water and aids in transporting that water into vegetative cells, which would be detrimental to endospores.
B It binds to calcium ions to destabilize DNA at room temperature.
C It binds to calcium ions to stabilize DNA at room temperatures.
D It binds free water and aids in dehydration, which would be detrimental to vegetative cells
D
Predict why dipicolinic acid is only found in endospores and not vegetative cells.
A It binds free water and aids in transporting that water into vegetative cells, which would be detrimental to endospores.
B It binds to calcium ions to destabilize DNA at room temperature.
C It binds to calcium ions to stabilize DNA at room temperatures.
D It binds free water and aids in dehydration, which would be detrimental to vegetative cells
D
What is the biological function of endospores?
A Endospores can serve as reproductive structures, enable survival in harsh environments, and transport toxins.
B They transport toxins.
C They enable organisms to endure extremes of temperature, drying, and nutrient depletion.
D They are bacterial reproductive structures.
C
When does endospore formation commence?
A following bacterial death
B when bacterial growth ceases due to limitation of an essential nutrient
C when bacteria are dividing exponentially
D when the bacterium is undergoing binary fission
B
The energy source derived from the charge separation across the cytoplasmic membrane is referred to as A the proton motive force. B the voltage source. C carbohydrate charging. D adenosine triphosphate.
A
Small acid-soluble proteins (SASPs) protect DNA from ultraviolet light and are found in high numbers within A inclusion bodies. B endospores. C gram-negative Bacteria. D gram-positive Bacteria.
B
