Microbiology - MCAT Biological and Biochemical Foundations of Living Systems
Card 1 of 712
Which of the following organelles is not bound by a membrane?
Which of the following organelles is not bound by a membrane?
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Ribosomes are not membrane-bound organelles. All of the other organelles are membrane-bound, and are thus only found in eukaryotes. Ribosomes, which are the site of protein synthesis, are found in both prokaryotes and eukaryotes.
Ribosomes are not membrane-bound organelles. All of the other organelles are membrane-bound, and are thus only found in eukaryotes. Ribosomes, which are the site of protein synthesis, are found in both prokaryotes and eukaryotes.
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What should a scientist look for if he is trying to determine whether a certain organism is a bacteria rather than a virus?
What should a scientist look for if he is trying to determine whether a certain organism is a bacteria rather than a virus?
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Bacteria can be killed by antibiotics, whereas viruses cannot.
Both bacteria and viruses have genetic material, can cause disease, and are smaller than eukaryotic cells. Neither of them has a nucleus.
Bacteria can be killed by antibiotics, whereas viruses cannot.
Both bacteria and viruses have genetic material, can cause disease, and are smaller than eukaryotic cells. Neither of them has a nucleus.
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Which recombinant process depends on a F factor plasmid?
Which recombinant process depends on a F factor plasmid?
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Beginning the process of conjugation requires the trait encoded by the F (fertility) plasmid. Transformation is the uptake of naked DNA, transduction is the transfer of genetic material via a virus, and translocation is the movement of a ribosome during protein translation.
Beginning the process of conjugation requires the trait encoded by the F (fertility) plasmid. Transformation is the uptake of naked DNA, transduction is the transfer of genetic material via a virus, and translocation is the movement of a ribosome during protein translation.
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Which of the following is false regarding plasmids?
Which of the following is false regarding plasmids?
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Plasmids are circular, double-stranded DNA molecules found outside the nucleoid (extrachomosomal DNA). They can serve a variety of functions and code for traits that may vary within a single species, since different individuals may carry different plasmids.
Most notable are the plasmids related to antibiotic resistance and plasmids required for formation of the sex pilus in conjugation. Recall that antibiotic resistance is the ability of a bacterial cell to survive in the presence of antibiotics. This ability is facilitated by antibiotic resistant proteins that are coded by certain genes found on the plasmid of a bacterial cell.
Plasmids are circular, double-stranded DNA molecules found outside the nucleoid (extrachomosomal DNA). They can serve a variety of functions and code for traits that may vary within a single species, since different individuals may carry different plasmids.
Most notable are the plasmids related to antibiotic resistance and plasmids required for formation of the sex pilus in conjugation. Recall that antibiotic resistance is the ability of a bacterial cell to survive in the presence of antibiotics. This ability is facilitated by antibiotic resistant proteins that are coded by certain genes found on the plasmid of a bacterial cell.
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What component is common for all viruses?
What component is common for all viruses?
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All viruses contain a protein coat (or capsule) that protects the genetic material (which can be either DNA or RNA). In some instances (such as herpes simplex), the virus can also contain an lipid envelope that serves as a membrane.
All viruses contain a protein coat (or capsule) that protects the genetic material (which can be either DNA or RNA). In some instances (such as herpes simplex), the virus can also contain an lipid envelope that serves as a membrane.
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Viral genomic material can be comprised of which types of nucleic acids?
I. Single-stranded DNA
II. Double-stranded DNA
III. Single-stranded RNA
IV. Double-stranded RNA
Viral genomic material can be comprised of which types of nucleic acids?
I. Single-stranded DNA
II. Double-stranded DNA
III. Single-stranded RNA
IV. Double-stranded RNA
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Different classes of viruses store genetic material in different forms.
Double-stranded RNA (dsRNA) viruses, single-stranded RNA (ssRNA) viruses, double-stranded DNA (dsDNA) viruses, and single-stranded DNA (ssDNA) viruses are all large classes of viral classification. Retroviruses can be classified as ssRNA viruses, but are often left in their own category.
Different classes of viruses store genetic material in different forms.
Double-stranded RNA (dsRNA) viruses, single-stranded RNA (ssRNA) viruses, double-stranded DNA (dsDNA) viruses, and single-stranded DNA (ssDNA) viruses are all large classes of viral classification. Retroviruses can be classified as ssRNA viruses, but are often left in their own category.
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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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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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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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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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