Microorganisms and Viruses - AP Biology
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Gram staining is a helpful technique for differentiating between different types of bacteria. What part of the bacterial envelope is exploited by the gram staining process?
Gram staining is a helpful technique for differentiating between different types of bacteria. What part of the bacterial envelope is exploited by the gram staining process?
The difference between gram-positive and gram-negative bacteria is the thickness of the peptidoglycan protein layer. Gram-positive bacteria have a thick peptidoglycan layer that retains the gram stain well, making it purple under a microscope. Gram-negative bacteria have a thinner peptidoglycan layer, and do not retain the stain as well as gram positive bacteria. This makes it pink when viewed under a microscope.
The difference between gram-positive and gram-negative bacteria is the thickness of the peptidoglycan protein layer. Gram-positive bacteria have a thick peptidoglycan layer that retains the gram stain well, making it purple under a microscope. Gram-negative bacteria have a thinner peptidoglycan layer, and do not retain the stain as well as gram positive bacteria. This makes it pink when viewed under a microscope.
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Which of the following can be found in prokaryotes, but never in viruses?
Which of the following can be found in prokaryotes, but never in viruses?
Prokaryotes create their own proteins, which means that ribosomes are present in the cell. Viruses, however, rely on the ribosomes of the host cell in order to create proteins. This means that ribosomes are not present in viruses, but are present in prokaryotes.
DNA and RNA will both be found in prokaryotes. Some viruses will contain DNA, while others will contain RNA. Attachment proteins allow viruses to bind to cell membranes, but also can allow one cell to bind to another.
Prokaryotes create their own proteins, which means that ribosomes are present in the cell. Viruses, however, rely on the ribosomes of the host cell in order to create proteins. This means that ribosomes are not present in viruses, but are present in prokaryotes.
DNA and RNA will both be found in prokaryotes. Some viruses will contain DNA, while others will contain RNA. Attachment proteins allow viruses to bind to cell membranes, but also can allow one cell to bind to another.
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Bacterial ribosomes contain a __________ and __________ subunit. This forms a __________ ribosome.
Bacterial ribosomes contain a __________ and __________ subunit. This forms a __________ ribosome.
Recall that bacterial ribosomes contain a 30S and a 50S subunit. The ribosome itself is a 70S ribosome, as the combination of the two subunits results in a smaller mass than the two separate units. Eukaryotic ribosomes contain a 40S and 60S subunit and form an 80S ribosome.
Recall that bacterial ribosomes contain a 30S and a 50S subunit. The ribosome itself is a 70S ribosome, as the combination of the two subunits results in a smaller mass than the two separate units. Eukaryotic ribosomes contain a 40S and 60S subunit and form an 80S ribosome.
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Which of the following statements is true regarding flagella?
Which of the following statements is true regarding flagella?
Flagella are used for mobility by both prokaryotes (bacteria) and eukaryotes. In humans, you can find these structures in sperm cells, which are propelled by the motion of flagella. Similarly, bacterial cells move through the environment with the aid of flagella. The key difference between a bacterial and eukaryotic flagellum is its composition. Bacterial flagella are made up of a protein called flagellin, whereas eukaryotic flagella are made up of microtubules, formed from the protein tubulin.
Flagella are used for mobility by both prokaryotes (bacteria) and eukaryotes. In humans, you can find these structures in sperm cells, which are propelled by the motion of flagella. Similarly, bacterial cells move through the environment with the aid of flagella. The key difference between a bacterial and eukaryotic flagellum is its composition. Bacterial flagella are made up of a protein called flagellin, whereas eukaryotic flagella are made up of microtubules, formed from the protein tubulin.
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What compound is present in both gram-positive and gram-negative bacteria?
What compound is present in both gram-positive and gram-negative bacteria?
Only gram-negative bacteria have an outer membrane. This outer membrane contains lipopolysaccharides. Gram-positive bacteria have only one membrane.
Teichoic acids are present only in gram-positive bacteria. They contribute to the thickness of the peptidoglycan layer.
Both types of bacteria have peptidoglycan. Gram-positive bacteria have a thick layer, due to the presence of teichoic acids. This allows them to retain the gram stain and appear purple. Gram-negative bacteria have a thin peptidoglycan layer, causing them to appear pink under gram staining.
Only gram-negative bacteria have an outer membrane. This outer membrane contains lipopolysaccharides. Gram-positive bacteria have only one membrane.
Teichoic acids are present only in gram-positive bacteria. They contribute to the thickness of the peptidoglycan layer.
Both types of bacteria have peptidoglycan. Gram-positive bacteria have a thick layer, due to the presence of teichoic acids. This allows them to retain the gram stain and appear purple. Gram-negative bacteria have a thin peptidoglycan layer, causing them to appear pink under gram staining.
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If a colony of round or oval-shaped bacteria are arranged in a random grape-like cluster, they must be:
If a colony of round or oval-shaped bacteria are arranged in a random grape-like cluster, they must be:
The two most common bacterial arrangements are Staph- and Strep-. Staph- is a non-symmetrical arrangement like a cluster of grapes. Strep- indicates a chain of bacteria.
The three most common bacterial shapes are listed below.
Coccus—round or oval
Bacillus—rectangular or rod-shaped
Spirilla (spirochete)—spiral
By breaking down names into arrangement and shape, students can predict or identify the appearance of an organism by its name. In the example Staph indicates arrangement in a chain. Coccus indicates round or oval in shape. Therefore, Staphylococci are round or oval-shaped organisms arranged in a cluster.
The two most common bacterial arrangements are Staph- and Strep-. Staph- is a non-symmetrical arrangement like a cluster of grapes. Strep- indicates a chain of bacteria.
The three most common bacterial shapes are listed below.
Coccus—round or oval
Bacillus—rectangular or rod-shaped
Spirilla (spirochete)—spiral
By breaking down names into arrangement and shape, students can predict or identify the appearance of an organism by its name. In the example Staph indicates arrangement in a chain. Coccus indicates round or oval in shape. Therefore, Staphylococci are round or oval-shaped organisms arranged in a cluster.
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An opportunistic pathogen that is an acidophile would cause the biggest concern if entering the body through which natural barrier?
An opportunistic pathogen that is an acidophile would cause the biggest concern if entering the body through which natural barrier?
The genito-urinary, respiratory, and digestive systems, as well as skin and mucous membranes, are natural physical barriers against infection.
Opportunistic microorganisms are normal fauna that are usually harmless; however, given the opportunity of a breach of any of our natural barriers, these organisms can invade vulnerable systems and cause infection, thus becoming pathogenic.
A pathogen that is an acidophile prefers highly acidic environments and therefore could survive the stomach's 2.0 pH - a lethal barrier to most organisms. The effectiveness of other natural barriers, however, would not be different because the organism is an acidophile.
The genito-urinary, respiratory, and digestive systems, as well as skin and mucous membranes, are natural physical barriers against infection.
Opportunistic microorganisms are normal fauna that are usually harmless; however, given the opportunity of a breach of any of our natural barriers, these organisms can invade vulnerable systems and cause infection, thus becoming pathogenic.
A pathogen that is an acidophile prefers highly acidic environments and therefore could survive the stomach's 2.0 pH - a lethal barrier to most organisms. The effectiveness of other natural barriers, however, would not be different because the organism is an acidophile.
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The aldehyde chemical family contains powerful microbial killing agents. Which bacterial structures do they effect?
The aldehyde chemical family contains powerful microbial killing agents. Which bacterial structures do they effect?
Aldehydes are powerful, toxic chemicals which work by denaturing DNA and RNA (nucleic acids).
Modern antibiotics are less toxic and work by disrupting cells' production of ribosomes. Common household cleaners, containing chlorine, work by oxidizing cell membranes. Older antibiotics, such as penicillin, work by dissolving cell walls. These modes of destruction are also known as mechanisms of cell death.
Aldehydes are powerful, toxic chemicals which work by denaturing DNA and RNA (nucleic acids).
Modern antibiotics are less toxic and work by disrupting cells' production of ribosomes. Common household cleaners, containing chlorine, work by oxidizing cell membranes. Older antibiotics, such as penicillin, work by dissolving cell walls. These modes of destruction are also known as mechanisms of cell death.
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Leukocytes are classified as either granulocytes or agranulocytes. Which of the following are granulocytes?
Leukocytes are classified as either granulocytes or agranulocytes. Which of the following are granulocytes?
Leukocytes can be broken down into the following categories and cells types.
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Leukocytes can be broken down into the following categories and cells types.
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Which of the following would be considered a lethal means of controlling bacterial endospores?
Which of the following would be considered a lethal means of controlling bacterial endospores?
Spores can survive most methods of control and are resistant to cold and heat. Pasteurization is a heating process that destroys some pathogenic microorganisms in foods and beverages, but does not kill spores. Boiling is not considered a reliable lethal control because the destruction of bacterial spores cannot be guaranteed. Cold temperature is a non-lethal means of microbial control that can slow multiplication or induce stasis, but cold is only effective while conditions are maintained.
Incineration is the use of extreme temperature to reduce matter to ash and is an effective means of sterilization.
Spores can survive most methods of control and are resistant to cold and heat. Pasteurization is a heating process that destroys some pathogenic microorganisms in foods and beverages, but does not kill spores. Boiling is not considered a reliable lethal control because the destruction of bacterial spores cannot be guaranteed. Cold temperature is a non-lethal means of microbial control that can slow multiplication or induce stasis, but cold is only effective while conditions are maintained.
Incineration is the use of extreme temperature to reduce matter to ash and is an effective means of sterilization.
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Which of the following does not describe a detergent action against bacteria?
Which of the following does not describe a detergent action against bacteria?
Detergents, or soaps, are non-lethal microbial controls. They emulsify lipids and oils, making it easier to wash them away. The action of washing away substances is strictly a mechanical mode of action. Detergents provide only static control, and have no killing power.
Detergents, or soaps, are non-lethal microbial controls. They emulsify lipids and oils, making it easier to wash them away. The action of washing away substances is strictly a mechanical mode of action. Detergents provide only static control, and have no killing power.
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A cell placed in an environment in which there are more solutes outside the cell than inside the cell will __________ and is said to be in a __________ environment.
A cell placed in an environment in which there are more solutes outside the cell than inside the cell will __________ and is said to be in a __________ environment.
We need to know the different between hypertonic, hypotonic, and isotonic. An environment is said to be hypertonic is there are more solute outside of the cell than inside. Since these solutes do not cross the cellular membrane very easily, but water can cross, water will travel out of the cell to balance the concentrations. This would cause the cell to shrink and shrivel.
The opposite is true for a hypotonic scenario, in which the cell will swell and maybe burst as water flows from the environment into the solute-filled cell. An isotonic environment is one in which solute concentrations are even, so there is no net movement of water into or out of the cell.
We need to know the different between hypertonic, hypotonic, and isotonic. An environment is said to be hypertonic is there are more solute outside of the cell than inside. Since these solutes do not cross the cellular membrane very easily, but water can cross, water will travel out of the cell to balance the concentrations. This would cause the cell to shrink and shrivel.
The opposite is true for a hypotonic scenario, in which the cell will swell and maybe burst as water flows from the environment into the solute-filled cell. An isotonic environment is one in which solute concentrations are even, so there is no net movement of water into or out of the cell.
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One mode of bacterial reproduction involves the formation of a bridge between two adjacent bacterial cells. This bridge is used to transport genetic material from one cell to the other. This mode of reproduction is called __________.
One mode of bacterial reproduction involves the formation of a bridge between two adjacent bacterial cells. This bridge is used to transport genetic material from one cell to the other. This mode of reproduction is called __________.
Formation of a bridge between two cells occurs during conjugation. The bridge is called a sex pilus, which is used to carry genetic material from one bacterial cell to the other.
Transduction is another mode of reproduction, but involves transmission of genetic material through a vector. Vectors are generally host cells or virions that carry parts of the bacterial genome known as plasmids.
The third type of bacterial reproduction is called transformation. In transformation a bacterial cell engulfs and incorporates genetic material from its surroundings.
Translation is not a type of bacterial reproduction; it is the process by which proteins are made from mRNA.
Formation of a bridge between two cells occurs during conjugation. The bridge is called a sex pilus, which is used to carry genetic material from one bacterial cell to the other.
Transduction is another mode of reproduction, but involves transmission of genetic material through a vector. Vectors are generally host cells or virions that carry parts of the bacterial genome known as plasmids.
The third type of bacterial reproduction is called transformation. In transformation a bacterial cell engulfs and incorporates genetic material from its surroundings.
Translation is not a type of bacterial reproduction; it is the process by which proteins are made from mRNA.
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Which of the following eukaryotic cellular processes does not occur in bacterial cells?
Which of the following eukaryotic cellular processes does not occur in bacterial cells?
Similar to eukaryotes, bacterial cells are in accordance with the central dogma of molecular biology. The flow of genetic information involves replication, transcription, and translation. Bacterial cells have to replicate their genetic material (replication), undergo transcription to convert DNA to mRNA, and go through translation to produce proteins from the mRNA.
Bacterial cells do not undergo mitosis or meiosis. Cell division can occur through other modes, such as binary fission. Since bacteria lack nuclei and other complex structures, their processes for cellular division are much more abbreviated and do not follow the same steps as eukaryotic mitosis.
Similar to eukaryotes, bacterial cells are in accordance with the central dogma of molecular biology. The flow of genetic information involves replication, transcription, and translation. Bacterial cells have to replicate their genetic material (replication), undergo transcription to convert DNA to mRNA, and go through translation to produce proteins from the mRNA.
Bacterial cells do not undergo mitosis or meiosis. Cell division can occur through other modes, such as binary fission. Since bacteria lack nuclei and other complex structures, their processes for cellular division are much more abbreviated and do not follow the same steps as eukaryotic mitosis.
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A researcher performs gram-staining on two different bacterial cells. Using a microscope, he observes that cell A is pink whereas cell B is purple. Based on this information, what can he conclude about the two bacterial cells?
A researcher performs gram-staining on two different bacterial cells. Using a microscope, he observes that cell A is pink whereas cell B is purple. Based on this information, what can he conclude about the two bacterial cells?
Recall that pink stained cells are gram-negative, whereas purple stained cells are gram-positive. Based on color, we can conclude that cell A is gram-negative (pink) and cell B is gram-positive (purple). One of the characteristics of gram-positive cells is that they have a thick cell wall. The thick peptidoglycan cell wall stops the gram stain from leaking out, resulting in a darker color.
Since cell B is purple, we can conclude that it is gram-positive and has a thick cell wall.
Recall that pink stained cells are gram-negative, whereas purple stained cells are gram-positive. Based on color, we can conclude that cell A is gram-negative (pink) and cell B is gram-positive (purple). One of the characteristics of gram-positive cells is that they have a thick cell wall. The thick peptidoglycan cell wall stops the gram stain from leaking out, resulting in a darker color.
Since cell B is purple, we can conclude that it is gram-positive and has a thick cell wall.
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Which of the following is true regarding gram-positive and gram-negative bacteria?
Which of the following is true regarding gram-positive and gram-negative bacteria?
First, remember that all bacterial cell walls contain peptidoglycan. The difference between gram-positive and gram-negative bacterial cell walls rises from the composition of peptidoglycan. Gram-negative bacteria appear pink when observed through a microscope, not purple. Also, gram-negative bacteria have thinner cell walls than their counterparts.
Gram-positive bacteria have half as many cell membranes as gram-negative bacteria. This is true because gram-negative bacteria contain an extra cell membrane outside their cell wall. Gram-negative bacteria have two cell membranes, whereas gram-positive bacteria only have one.
First, remember that all bacterial cell walls contain peptidoglycan. The difference between gram-positive and gram-negative bacterial cell walls rises from the composition of peptidoglycan. Gram-negative bacteria appear pink when observed through a microscope, not purple. Also, gram-negative bacteria have thinner cell walls than their counterparts.
Gram-positive bacteria have half as many cell membranes as gram-negative bacteria. This is true because gram-negative bacteria contain an extra cell membrane outside their cell wall. Gram-negative bacteria have two cell membranes, whereas gram-positive bacteria only have one.
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What happens to a bacterial cell if you place it in a hypotonic solution?
What happens to a bacterial cell if you place it in a hypotonic solution?
If you place a cell in a hypotonic solution it means that the solution contains less solute (and more water) than the cell’s cytosol. Recall that osmosis causes water to go from a region of high water content (few solutes) to a region of low water content (more solutes).
In this case, the water will go from the solution to the inside of the cell, causing the cell to swell.
If you place a cell in a hypotonic solution it means that the solution contains less solute (and more water) than the cell’s cytosol. Recall that osmosis causes water to go from a region of high water content (few solutes) to a region of low water content (more solutes).
In this case, the water will go from the solution to the inside of the cell, causing the cell to swell.
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Staphylococcus aureus is a bacterium that causes skin infections and respiratory disease. What shape is this bacterium?
Staphylococcus aureus is a bacterium that causes skin infections and respiratory disease. What shape is this bacterium?
The name staphylococcus aureus contains the term "coccus," which indicates that the bacteria is round-shaped.
Rod shaped bacteria are classified as bacilli and helical bacteria are classified as spirilla.
The name staphylococcus aureus contains the term "coccus," which indicates that the bacteria is round-shaped.
Rod shaped bacteria are classified as bacilli and helical bacteria are classified as spirilla.
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Which is not a difference between prokaryotes and eukaryotes?
Which is not a difference between prokaryotes and eukaryotes?
All of these answers are true differences between prokaryotes and eukaryotes. Prokaryotes' DNA is double-stranded, but circular instead of linear, as in eukaryotes. This facilitates the expedient replication of multiple genes. Eukaryotes have membrane-bound organelles, but prokaryotes do not. The more complex a cell is, the greater number of reactions and processes that need to be separated. Eukaryotes also have multiple replication origins most likely due to the length and distribution of their genes. Eukaryotes also do not have operons (present in prokaryotes) that are analogous to "gene packets," which are transcribed simultaneously. Since prokaryotic DNA is circular they have no "ends". Thus there are no need for telomeres which cover the ends of eukaryotic chromosomes. This loss of important genetic information at the end of transcription due to the antiparallel nature of DNA.
All of these answers are true differences between prokaryotes and eukaryotes. Prokaryotes' DNA is double-stranded, but circular instead of linear, as in eukaryotes. This facilitates the expedient replication of multiple genes. Eukaryotes have membrane-bound organelles, but prokaryotes do not. The more complex a cell is, the greater number of reactions and processes that need to be separated. Eukaryotes also have multiple replication origins most likely due to the length and distribution of their genes. Eukaryotes also do not have operons (present in prokaryotes) that are analogous to "gene packets," which are transcribed simultaneously. Since prokaryotic DNA is circular they have no "ends". Thus there are no need for telomeres which cover the ends of eukaryotic chromosomes. This loss of important genetic information at the end of transcription due to the antiparallel nature of DNA.
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Which description does not apply to bacteria?
Which description does not apply to bacteria?
Bacteria are a type of prokaryote, which do not have any membrane-bound organelles, but do have circular, doubled-stranded DNA, ribosomes, and an outer membrane made of proteins and lipids. Since glycolysis does not require any organelles, it occurs in they cytoplasm of both prokaryotes and eukaryotes.
Bacteria are a type of prokaryote, which do not have any membrane-bound organelles, but do have circular, doubled-stranded DNA, ribosomes, and an outer membrane made of proteins and lipids. Since glycolysis does not require any organelles, it occurs in they cytoplasm of both prokaryotes and eukaryotes.
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