It is the same in Gram-positive and Gram-negative bacteria
Correct Answer: It protects the cell from the environment
Peptidoglycan is the primary component of the cell wall
Correct Answer: Peptidoglycan
The three phases of peptidoglycan biosynthesis occur in the following order: a cytoplasmic phase, a membrane-associated phase, and an extracytoplasmic phase.
Correct Answer: None of the choices
Peptidoglycan is a structure composed of repeating molecules of the sugars N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).
Correct Answer: Repeating N-acetylglucosamine and N-acetylmuramic acid molecules
The cell walls of Gram-positive bacteria contain a thick layer of peptidoglycan
Correct Answer: Gram-positive
Gram-negative bacteria have a thin layer of peptidoglycan but also have an outer membrane, which is also known as the lipopolysaccharide layer (LPS layer).
Correct Answer: Gram-negative
In addition to many layers of peptidoglycan, the cell wall of Gram-positive bacterial cells also contains teichoic acid molecules.
Correct Answer: Gram-positive
The LPS layer of Gram-negative bacteria is an endotoxin.
The outer membrane of Gram-negative bacteria is also known as the lipopolysaccharide layer (LPS layer) because it is composed of lipids, proteins, and polysaccharides.
Exotoxins are secreted from Gram-positive organisms.
M proteins are major virulence factor produced by some Gram-positive Streptococcus species.
Correct Answer: Is a virulence factor in streptococcal infections
Mycoplasma have a cell membrane but no cell wall.
Correct Answer: No cell wall
The cell wall of Mycobacterium (an acid-fast bacteria) contains up to 60% mycolic acid, which makes them extremely resistant to environmental stress, and provides a barrier that prevents the actions of many antibiotics and many host defence mechanisms.
Correct Answer: It is a minor cell wall component
Porin proteins create channels of different pore size and specificity and therefore control the transport of molecules, including antibiotics, into the cell. Genes for porins can become mutated when subjected to antibiotic treatment, causing a decrease in pore size that prevents even small antibiotics from entering the cell. The organism therefore becomes resistant to antibiotics.
Correct Answer: Become larger during attack with antibiotics
Lipid A is found in the outer layer of Gram-negative cells and is the primary component of endotoxin. It is released when Gram-negative organisms die.
Correct Answer: Part of the endotoxins of Gram-negative bacteria
O polysaccharides are carbohydrate chains that are part of the outer (not plasma) membrane of Gram-negative bacteria and are located on the side of the membrane that faces the extracellular fluid. These molecules vary from one bacterial species to another and can be recognized by the immune system. In addition, they can be used as a diagnostic tool for the identification of certain bacteria, such as E.coli.
Correct Answer: Used to identify certain bacteria
Streptococcus pneumoniae is not infectious unless it is encapsulated.
Correct Answer: Streptococcal infection
Neisseria gonorrhoeae is infectious only if fimbriae are present.
Correct Answer: Gonorrhea
Helicobacter pylori causes gastric ulcers in humans. It lives in the folds of the stomach and uses powerful flagellar movements to propel itself into the heavy layer of mucus that protects the epithelial cells of the stomach from stomach acids.
Correct Answer: Helicobacter infection in stomach
The infectious process associated with Treponema pallidum (the causative agent of syphilis) requires the corkscrew rotational motion created by axial filaments, which allow it to bore through tissue.
Correct Answer: Syphilis
Fimbriae, pili, axial filaments, flagella, and the plasma membrane all have direct clinical relevance but only the plasma membrane is a target for antibiotics.
Correct Answer: Plasma membrane
Bacterial inclusion bodies have not been shown to have clinical relevance.
Correct Answer: Bacterial inclusion bodies
Peritrichous is the arrangement in which flagella are distributed all over the cell.
Correct Answer: Peritrichous flagella
The fundamental structure of cell membranes is the phospholipid bilayer configuration. They do not contain Lipid A.
Correct Answer: A phospholipid bilayer
Integral proteins are membrane proteins that go all the way through the plasma membrane, and in some cases contain a pore that connects the cell interior to the external environment. Bacteria do not have a nucleus.
Correct Answer: Go all the way through the membrane
Plasmolysis occurs when a cell is placed in a hypertonic environment and the cell membrane pulls away from the cell wall.
Correct Answer: Plasmolysis
Simple diffusion refers to diffusion across a semipermeable membrane, which is hypertonic with respect to a solute. The solute moves from the side where its concentration is higher (the hypertonic) to the other side (hypotonic side). Water moves from the place where its concentration is higher (hypotonic) to the hypertonic side. This requires no energy from ATP since the system is returning to isotonic equilibrium.
Correct Answer: Active transport
Group translocation is unique to bacteria and is a type of active transport that uses PEP as its energy source.
Correct Answer: PEP
A plasmid is a smaller circular fragment of DNA that is separate from the bacterial chromosome.
Correct Answer: Extrachromosomal pieces of DNA
Bacterial ribosomes are made up of two subunits, are not the same as those seen in eukaryotic cells, and are not membrane bound.
Correct Answer: Are involved in protein synthesis
Tetracyclines, aminoglycosides and macrolides inhibit bacterial ribosomes. They exploit the difference in structure of between prokaryotic and eukaryotic ribosomes to enable selective toxicity. Ribosomes translate mRNA into proteins and are indispensable for cell growth, but they are only indirectly necessary for infection, are not part of the production of plasmids, and are not part of endotoxins.
Correct Answer: Are targets for antibiotic therapy
Endospores are the most resistant structures found in bacteria and are particularly resistant to heat. They are also resistant to desiccation, toxic chemicals, antibiotics and ultraviolet irradiation. Endospores are not part of the division process but are formed by some species of bacteria in response to too great environmental stress.
Correct Answer: Resistant to heat