Quiz 1 questions Flashcards
also explain why answers are right or wrong (20 cards)
Which of the following does NOT accurately describe…
The structure of peptidoglycan in E. coli?
A) The peptidoglycan is only a single layer thick and loosely crosslinked
B) Cross-linking occurs between the 3rd amino acid of one tetrapeptide and the 4th amino acid of another tetrapeptide on an adjacent glycan chain
C) Cross-links involve the unusual amino acid diaminopimelic acid
D) The amino acids in the tetrapeptide are connected to each other by peptide bonds
E) N-acetyl glucosamine is linked to N-acetyl muramic acid by a β-1,3 glycosidic bond
E) N-acetyl glucosamine is linked to N-acetyl muramic acid by a β-1,3 glycosidic bond
-E. coli have peptidoglycan, so B1,4 bonds not B-1,3, that’s archaea
Lipopolysaccharides:
A) Link the peptidoglycan layer to the cytoplasmic membrane
B) Are an important constituent of the periplasm
C) Are found in Staphylococcus aureus’s cell wall
D) Help acidic stains to stick to a cell’s surface
E) Are not found in bacteria that produce endospores
E) Are not found in bacteria that produce endospores
Bc only some gram positive bacteria produce endospores and LPS are in outer membrane, which gram positive bacteria don’t have.
Which of the following statements BEST describes:
the evolutionary tree of life based on 16S rRNA gene sequencing?
A) It shows that all prokaryotes are more closely related to each other than they are to eukaryotes
B) It shows that modern day eukaryotes evolved from a branch of prokaryotes called archaea
C) It divides all microorganisms into three fundamental groups: those with prokaryotic cell structure, those with eukaryotic cell structure, and those that do not consist of cells.
D) It shows that all cellular organisms descended from a universal common ancestor, and that universal common ancestor was a virus
E) It shows that bacteria and archaea diverged from each other many billions of years ago, and that eukaryotes arose from bacteria shortly after that
B) It shows that modern day eukaryotes evolved from a branch of prokaryotes called archaea
A is incorrect becuase archaea are prokaryotes that are more closely related to eukaryotes than other prokaryotes (bacteria).
A membrane protein that allows protons to pass through the cytoplasmic membrane while simultaneously bringing a nutrient into the cell is a(n):
A) Phosphotransferase system
B) Antiporter
C) ABC transporter
D) Symporter
E) Porin
D) Symporter
bringing in and simultaneously =same direction so symporter, if it was exiting in opp direction then antiport
Which of the following groups of microbes are prokaryotic?
A) Bacteria
B) Algae
C) Slime molds
D) Viruses
E) More than one of the above
A) Bacteria
sime molds and algae are protists (eukaryotic), and viruses are not in a domain (not alive).
The cytoplasmic membrane:
A) Is made of basically the same macromolecules in all three domains of life, bacteria, archaea and eukarya
B) Serves as an anchor for important structures on the outside of the cell, like pili and fimbriae
C) Contains phospholipids and lipopolysaccharides, but the exact nature of the lipopolysaccharides is different from those of the outer membrane
D) Is freely permeable to important nutrients like glucose and amino acids, allowing them to diffuse through according to their concentration gradients
E) Provides shape to bacterial cells, and helps to protect them from osmotic lysis
B) Serves as an anchor for important structures on the outside of the cell, like pili and fimbriae
(the CM is made of diff.phospholipids in archaea monolayer, also the CM does not have lipopolysaccharides)
Which of the following statements is true of Archaea?
A) They are genetically more closely related to eukaryotes than they are to bacteria
B) They sometimes cause pneumonia and other respiratory infections in humans
C) Their cell walls contain N-acetyl glucosamine connected to N-acetyl muramic acid by β1-4 glycosidic bonds
D) None of the above statements are true
A) They are genetically more closely related to eukaryotes than they are to bacteria
(they are a branch of eukaryotes)
-nonpathogenic (can’t cause infection), don’t have peptidoglycan in cell walls, they have pseudomurein, so not N-acetyl muramic acid, and B1-3 bonds instead)
Mycoplasmas are bacteria that:
A) Are among the largest cellular organisms known
B) Contain both peptidoglycan and lipopolysaccharide
C) Contain neither lipopolysaccharide nor lipoteichoic acid
D) Can only be seen with the microscope if they are first stained with the acid fast staining technique
E) More than one of the above is true
C) Contain neither lipopolysaccharide nor lipoteichoic acid
Are smallest not largest. Mycoplasmas are bacteria** without cell walls **so they don’t have LPS or lipoteichoic acid cuz those are cell wall components. And not part of mycobacterium genus which need acid fast stain to detect mycolic acid in CELL WALL which mycoplasmas don’t have.
Which of the following best describes the “core polysaccharide”?
A) It is the most external structure of the outer membrane
B) The exact sugars in its structure are fairly constant, and don’t vary much between closely related species
C) It helps link the peptidoglycan layer to the cell membrane
D) It is only found in Gram positive bacteria
E) It is a toxin that can cause vomiting and diarrhea in humans
B) The exact sugars in its structure are fairly constant, and don’t vary much between closely related species
not most external cuz ‘core’, most external is O-specific polysaccharide
True or False: All archaea have pseudomurein.
False, only some methanogenic archaea do, others cell walls can be made of polysaccharide, protein, glycoprotein, or other complex macromolecules.
Dark-field microscopy is a technique that makes bacteria appear bright against a dark background and can be particularly useful for viewing bacteria that don’t stain well like ________________.
A) Mycobacterium tuberculosis
B) Escherichia coli
C) Streptococcus pyogenes
D) Bacillus anthracis
E) Treponema pallidum
E) Treponema pallidum
Which of the following structures is NOT correctly matched to it’s function in the bacterial cell?
A) Slime layer - can help the cell stick to surfaces and form a biofilm
B) Endospore - can resist damage from heat, chemicals and age
C) Fimbriae - used to transfer genetic material to another bacterium
D) Magnetosomes - allows the cell to orient itself in a magnetic field
E) Poly-β-hydroxybutyrate (or polyhydroxyalkanoate) - a storage of carbon and energy
C) Fimbriae -used to tranfer genetic material to another bacterium.
Pili is the only label that can be used to describe a structure that does this.
True or False: All bacteria have a cell wall.
False, mycoplasma are bacteria without a cell wall
Why was Robert Koch’s research on anthrax so important to the development of microbiology as a science?
A) Because it showed that all living organisms were composed of cells, including the smallest microbes
B) Because it showed that microbes cannot arise from nothingness, they must be injected into an animal to make it sick
C) Because it led to the development of agar petri plates and of the techniques used to obtain pure cultures
D) Because it led to rules for the naming of microorganisms, and other scientists would not be able to describe their results if the organisms they studied didn’t even have names
C) Because it led to the development of agar petri plates and of the techniques used to obtain pure cultures
(he realized solid media was a simple way to get pure cultures)
Louis Pasteur was the one who showed that microbes can’t arise from nothingness (spontaneous generation).
The enzyme glycerophosphate acyl transferase plays a key role in the synthesis of ester phospholipids. Where is the gene for this enzyme likely to be encoded in E. coli?
A) The gene for glycerophosphate acyl transferase is most likely encoded in the chromosome
B) The gene for glycerophosphate acyl transferase is most likely encoded on a plasmid
C) The gene for glycerophosphate acyl transferase is most likely encoded in ribosomal RNA
D) Any of the three options given above seem like reasonable locations for carrying this gene
E) This gene is not likely to be encoded anywhere in E. coli’s genome, because E. coli produces ether phospholipids
A) The gene for glycerophosphate acyl transferase is most likely encoded in the chromosome
It’s an essential gene bc it codes for an esential process, so it would be in chromosome, plasmid is for genes that aren’t always needed.
Which structure in the bacterial cell envelope gives strength and rigidity to the cell?
Peptidoglycan in cell wall. Layer above phospholipid bilayer in gram positive, between CM and outer membrane in gram negative.
True or False: The energy required to move the sugar lactose into a growing E. coli cell is supplied by the proton motive force, whereas the energy used to transport glucose is supplied by phosphoenolpyruvate.
True
to move lactose symport is used >PMF . to move glucose Phosphoenolpyruvate (PEP) donates a PO43- group to a
phosphorelay system, through protein carriers to substrate to modify.
If you see double bonded O to a Carbon what bond phospholipids is this and what domain does it belong to
- Ester bond
- Eukarya and bacteria
True or false: Electron microscopy provides much greater magnification than a light microscope, but because it requires the sample to be stained with metals like lead or uranium, the resolution is not as good.
False, electron microscopy provides greater magnification and resolution. However it may not be as accurate to natural microbe because it’s so manipulated and definetely not alive.
Which of the following statements is true?
A) Because bacteria reproduce asexually, they do not evolve over time like eukaryotes do
B) Only prokaryotes can turn the nitrogen gas from the air into a bioavailable form
C) All bacteria make people sick
D) Microbes have lived on this planet for about the same amount of time as plants and animals
E) More than one of the above statements are true
B) Only prokaryotes can turn the nitrogen gas from the air into a bioavailable form
Some bacteria is good for your gut for example, doesn’t make you sick.
