Bacteria and Types of Prokaryotes - MCAT Biological and Biochemical Foundations of Living Systems
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Gram staining prepares bacteria to be visualized under light microscope.
What allows a bacteria to stain positively with gram stain?
Gram staining prepares bacteria to be visualized under light microscope.
What allows a bacteria to stain positively with gram stain?
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Gram-positive bacteria are able to retain the crystal violet stain found in gram stain because of their thick peptidoglycan cell walls. Consequently, these bacteria stain dark blue or purple by gram staining. Alternatively, gram-negative bacteria appear red or pink because they are unable to retain the dye due to thinner cell walls and less peptidoglycan.
Gram-positive bacteria are able to retain the crystal violet stain found in gram stain because of their thick peptidoglycan cell walls. Consequently, these bacteria stain dark blue or purple by gram staining. Alternatively, gram-negative bacteria appear red or pink because they are unable to retain the dye due to thinner cell walls and less peptidoglycan.
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Which of the following would not be found an E. Coli sample?
Which of the following would not be found an E. Coli sample?
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E. Coli is a type of bacteria. Because bacteria are prokaryotes, they do not contain membrane-bound organelles. A nucleus is a membrane-bound organelle and therefore would not be found in bacteria.
E. Coli is a type of bacteria. Because bacteria are prokaryotes, they do not contain membrane-bound organelles. A nucleus is a membrane-bound organelle and therefore would not be found in bacteria.
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All of the following are true about bacilli bacteria except:
I. All bacilli are rod-shaped
II. All bacilli are gram positive
III. All bacilli are aerobic
All of the following are true about bacilli bacteria except:
I. All bacilli are rod-shaped
II. All bacilli are gram positive
III. All bacilli are aerobic
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Bacilli is a genus of bacteria that are characterized by their rod-shaped cells. Bacilli can be either gram positive, such as Bacillus anthracis, or gram negative, such as Salmonella enterica. Bacilli bacteria can be either aerobic (require oxygen) or facultative anaerobes (can thrive in both oxygen rich and oxygen poor environment). Bacilli are not exclusively aerobic, nor are they exclusively gram positive.
Bacilli is a genus of bacteria that are characterized by their rod-shaped cells. Bacilli can be either gram positive, such as Bacillus anthracis, or gram negative, such as Salmonella enterica. Bacilli bacteria can be either aerobic (require oxygen) or facultative anaerobes (can thrive in both oxygen rich and oxygen poor environment). Bacilli are not exclusively aerobic, nor are they exclusively gram positive.
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The presence of which of the following feature would best indicate a eukaryotic cell?
The presence of which of the following feature would best indicate a eukaryotic cell?
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Organelles are only found in eukaryotic cells which set them apart from prokaryotic cells.
Organelles are only found in eukaryotic cells which set them apart from prokaryotic cells.
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Slides containing bacteria are stained with crystal violet and iodine, destained with alcohol, and counterstained with safranin. Under the mircoscope, the bacteria appear a bluish-purple color. Which class of bacteria are on the slide?
Slides containing bacteria are stained with crystal violet and iodine, destained with alcohol, and counterstained with safranin. Under the mircoscope, the bacteria appear a bluish-purple color. Which class of bacteria are on the slide?
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The technique explained in the question is the "Gram stain". Bacteria that are Gram-positive will stain a bluish-purple color, while Gram-negative bacteria will stain a red or pink color. This difference in color occurs because of the large cell wall present on Gram-positive bacteria, and is a response to increased peptidoglycan expression. Additionally, some bacteria (such as mycobacteria and helicobacter) are not easily stained using this method.
The technique explained in the question is the "Gram stain". Bacteria that are Gram-positive will stain a bluish-purple color, while Gram-negative bacteria will stain a red or pink color. This difference in color occurs because of the large cell wall present on Gram-positive bacteria, and is a response to increased peptidoglycan expression. Additionally, some bacteria (such as mycobacteria and helicobacter) are not easily stained using this method.
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An unidentified class of bacteria are placed into a test tube containing liquid and set on top of a lab bench. After the liquid and bacteria has a chance to settle, the bacteria are found distributed throughout the liquid (as opposed to located primarily at the top or bottom of the liquid). What type of bacteria is in the tube?
An unidentified class of bacteria are placed into a test tube containing liquid and set on top of a lab bench. After the liquid and bacteria has a chance to settle, the bacteria are found distributed throughout the liquid (as opposed to located primarily at the top or bottom of the liquid). What type of bacteria is in the tube?
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In order for the bacteria to be distributed throughout the liquid, it must be able to survive in either the presence or absence of oxygen. Facultative anaerobic bacteria can surive in both cases, although, they prefer oxygen. In the absence of oxygen, they can produce energy through fermentation. Both microaerophiles and obligate aerobic bacteria require oxygen to survive and, in this experiment, would be found near the top of the tube. Oxygen is toxic to obligate anaerobic bacteria, which would be found at the bottom.
In order for the bacteria to be distributed throughout the liquid, it must be able to survive in either the presence or absence of oxygen. Facultative anaerobic bacteria can surive in both cases, although, they prefer oxygen. In the absence of oxygen, they can produce energy through fermentation. Both microaerophiles and obligate aerobic bacteria require oxygen to survive and, in this experiment, would be found near the top of the tube. Oxygen is toxic to obligate anaerobic bacteria, which would be found at the bottom.
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Which of the statements below describes eukaryotic, but not prokaryotic cells?
Which of the statements below describes eukaryotic, but not prokaryotic cells?
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Post-transcriptional modifications, such as the splicing out of introns, only occur in eukaryotic cells. They cannot occur in prokaryotes because in those cells, trancription and translation happen concurrently in the cytoplasm.
Both types of cell contain ribosomes, so this answer does not fulfill the question criteria. Cells that lack membrane-bound organelles and a nuclear membrane are prokaryotes, not eukaryotes. Similarly, only prokaryotes are capable of coupled transcription and translation mechanisms. Finally, the choice that references external plasmids also describes prokaryotes.
Post-transcriptional modifications, such as the splicing out of introns, only occur in eukaryotic cells. They cannot occur in prokaryotes because in those cells, trancription and translation happen concurrently in the cytoplasm.
Both types of cell contain ribosomes, so this answer does not fulfill the question criteria. Cells that lack membrane-bound organelles and a nuclear membrane are prokaryotes, not eukaryotes. Similarly, only prokaryotes are capable of coupled transcription and translation mechanisms. Finally, the choice that references external plasmids also describes prokaryotes.
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Which of the following is not a tenet of the Cell Theory?
Which of the following is not a tenet of the Cell Theory?
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All of the answer choices are tenets of the Cell Theory, except for the one concerning organelles. Not every cells has membrane-bound organelles (e.g. prokaryotic cells).
All of the answer choices are tenets of the Cell Theory, except for the one concerning organelles. Not every cells has membrane-bound organelles (e.g. prokaryotic cells).
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An unknown cell type has been isolated. It is suspected that this cell is prokaryotic. The presence of which of these cell structures would confirm that the cell is prokaryotic?
An unknown cell type has been isolated. It is suspected that this cell is prokaryotic. The presence of which of these cell structures would confirm that the cell is prokaryotic?
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Cytoplasm is found in all types of cells. Flagella is found in all cells that are mobile. Spores can be found in bacteria but also fungi. Ribosomes are found in prokaryotic cells albeit smaller in size compared to those in eukaryotic cells.
Cytoplasm is found in all types of cells. Flagella is found in all cells that are mobile. Spores can be found in bacteria but also fungi. Ribosomes are found in prokaryotic cells albeit smaller in size compared to those in eukaryotic cells.
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Which of the following components of an animal cell would NOT also be observed in a bacterial cell?
Which of the following components of an animal cell would NOT also be observed in a bacterial cell?
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This question is asking about one of the differences between eukaryotes and prokaryotes. While both eukaryotes and prokaryotes use DNA to encode their genetic information, making "DNA" incorrect, remember that prokaryotes lack membrane-bound organelles. \This makes both "ribosomes" and "phospholipid cell membrane" incorrect, because neither of them are membrane-bound organelles. We are left with "nucleus," which is the correct answer.
This question is asking about one of the differences between eukaryotes and prokaryotes. While both eukaryotes and prokaryotes use DNA to encode their genetic information, making "DNA" incorrect, remember that prokaryotes lack membrane-bound organelles. \This makes both "ribosomes" and "phospholipid cell membrane" incorrect, because neither of them are membrane-bound organelles. We are left with "nucleus," which is the correct answer.
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Which of the following would not be found in a prokaryotic cell?
Which of the following would not be found in a prokaryotic cell?
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One of the key differences between prokaryotes and eukaryotes is that prokaryotes have no membrane bound organelles, therefore, prokaryotes would not have mitochondria. Prokaryotes have a plasma membrane for protection, ribosomes for protein production, RNA in the form of mRNA, tRNA, and rRNA, and DNA polymerase to replicate their DNA.
One of the key differences between prokaryotes and eukaryotes is that prokaryotes have no membrane bound organelles, therefore, prokaryotes would not have mitochondria. Prokaryotes have a plasma membrane for protection, ribosomes for protein production, RNA in the form of mRNA, tRNA, and rRNA, and DNA polymerase to replicate their DNA.
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A scientist studying a culture of bacteria finds an organism he hadn't seen before. He thinks it might be some kind of single-celled eukaryote. What observed characteristic would support the scientists prediction?
A scientist studying a culture of bacteria finds an organism he hadn't seen before. He thinks it might be some kind of single-celled eukaryote. What observed characteristic would support the scientists prediction?
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The characteristic that defines a eukaryote is the presence of membrane bound organelles, such as the nucleus, mitochondria, Golgi body, and chloroplasts. Both eukaryotes and prokaryotes have ribosomes, DNA and RNA, and and electron trasnsport chain. Bacteria and plants have cell walls but not all eukaryotes do, so it is not a defining characteristic.
The characteristic that defines a eukaryote is the presence of membrane bound organelles, such as the nucleus, mitochondria, Golgi body, and chloroplasts. Both eukaryotes and prokaryotes have ribosomes, DNA and RNA, and and electron trasnsport chain. Bacteria and plants have cell walls but not all eukaryotes do, so it is not a defining characteristic.
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Which of the following is not a characteristic of prokaryotes?
Which of the following is not a characteristic of prokaryotes?
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Prokaryotes do not have membrane-bound organelles, such as the nucleus or mitochondria. In fact, endosymbiotic theory suggests that mitochondria evolved from symbiotic prokaryotic relationships. Prokaryotes are often associated with all of the other characteristics listed.
Prokaryotes do not have membrane-bound organelles, such as the nucleus or mitochondria. In fact, endosymbiotic theory suggests that mitochondria evolved from symbiotic prokaryotic relationships. Prokaryotes are often associated with all of the other characteristics listed.
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Which of the following would not help determine whether a cell was eukaryotic or prokaryotic?
Which of the following would not help determine whether a cell was eukaryotic or prokaryotic?
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Membrane bound organelles are specific only to eukaryotes. Circular DNA is only present in prokaryotes. Rough endoplasmic reticulum is only present in eukaryotes, as all prokaryotic ribosomes are cytoplasmic. Although prokaryotes have circular DNA, both eukaryotes and prokaryotes have double-stranded DNA.
Membrane bound organelles are specific only to eukaryotes. Circular DNA is only present in prokaryotes. Rough endoplasmic reticulum is only present in eukaryotes, as all prokaryotic ribosomes are cytoplasmic. Although prokaryotes have circular DNA, both eukaryotes and prokaryotes have double-stranded DNA.
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A scientist discovers a new bacteria growing on a plant in his house. He brings it into the lab to study its growth. He grows the new bacteria alongside a known obligate anaerobic bacteria, and sees that after an hour, the new bacteria has not grown as much as the anaerobic bacteria. What classification most likely describes the type of the new bacteria?
A scientist discovers a new bacteria growing on a plant in his house. He brings it into the lab to study its growth. He grows the new bacteria alongside a known obligate anaerobic bacteria, and sees that after an hour, the new bacteria has not grown as much as the anaerobic bacteria. What classification most likely describes the type of the new bacteria?
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Since the obligate anaerobe grows well, we know that both bacteria are grown in an anaerobic environment.
A facultative anaerobe can grow in an aerobic or anaerobic environment. It simply grows better when oxygen is present; therefore, we would see slower growth from a facultative anaerobe than an obligate anaerobe when there is no oxygen present. If the bacteria were aerobic, it would not grow at all in the anaerobic environment.
Since the obligate anaerobe grows well, we know that both bacteria are grown in an anaerobic environment.
A facultative anaerobe can grow in an aerobic or anaerobic environment. It simply grows better when oxygen is present; therefore, we would see slower growth from a facultative anaerobe than an obligate anaerobe when there is no oxygen present. If the bacteria were aerobic, it would not grow at all in the anaerobic environment.
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All of the following are characteristics of prokaryotic cells except for .
All of the following are characteristics of prokaryotic cells except for .
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Protists, fungi, plants, and animals are eukaryotic, while bacteria are prokaryotic. The rest of the answer choices are characteristic of prokaryotic cells.
Protists, fungi, plants, and animals are eukaryotic, while bacteria are prokaryotic. The rest of the answer choices are characteristic of prokaryotic cells.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is a key difference between human cells and Neisseria?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is a key difference between human cells and Neisseria?
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Prokaryotes like Neisseria do not have mitochondria, while eukaryotic human cells do. In fact, prokaryotes probably gave rise to the first mitochondria via the theory of endosymbiosis.
Prokaryotes like Neisseria do not have mitochondria, while eukaryotic human cells do. In fact, prokaryotes probably gave rise to the first mitochondria via the theory of endosymbiosis.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist is using a Gram stain to investigate Neisseria. If Neisseria is bright pink upon examination after staining, which of the following is likely true?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist is using a Gram stain to investigate Neisseria. If Neisseria is bright pink upon examination after staining, which of the following is likely true?
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Bright pink cells under Gram stain are characteristic of Gram negative status. This is associated with an outer lipid membrane and reduced peptidoglycan. The reduction in peptidoglycan is what leads to a failure to retain the Gram stain, which would have colored the cells purple.
Bright pink cells under Gram stain are characteristic of Gram negative status. This is associated with an outer lipid membrane and reduced peptidoglycan. The reduction in peptidoglycan is what leads to a failure to retain the Gram stain, which would have colored the cells purple.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist views his Gram stained Neisseria under a microscope, and finds that they are present in groups of two, each of which is a round cell. In what category of bacteria does Neisseria most likely fall?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A scientist views his Gram stained Neisseria under a microscope, and finds that they are present in groups of two, each of which is a round cell. In what category of bacteria does Neisseria most likely fall?
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Round bacterial cells are considered cocci. In this case, with two cells, it would be classified specifically as a diploccocus.
Round bacterial cells are considered cocci. In this case, with two cells, it would be classified specifically as a diploccocus.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The same scientist continues to explore Neisseria under a microscope, and makes a surprising finding for a bacterium. He wonders if the sample was mislabeled. Which of the following is likely to surprise this scientist if it were found in a sample that was labeled Neisseria?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The same scientist continues to explore Neisseria under a microscope, and makes a surprising finding for a bacterium. He wonders if the sample was mislabeled. Which of the following is likely to surprise this scientist if it were found in a sample that was labeled Neisseria?
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Prokaryotes like Neisseria do not have mebrane bound organelles, including nuclei. Their DNA is stored in the cytosol without the benefit of extensive sequestration.
Prokaryotes like Neisseria do not have mebrane bound organelles, including nuclei. Their DNA is stored in the cytosol without the benefit of extensive sequestration.
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