Antibodies and Antigens - MCAT Biological and Biochemical Foundations of Living Systems
Card 1 of 192
Which of the following combinations might yield the necessity of blood transfusion for a new born baby?
Which of the following combinations might yield the necessity of blood transfusion for a new born baby?
Tap to reveal answer
Rh factors are surface proteins found on red blood cells. An Rh-negative mother can be exposed to Rh-positive blood from the fetus in her first pregnancy. Without administration of Rh(o) D immunoglobulin during the delivery of her first baby, the mother can develop antibodies to Rh so that during her second pregnancy, the maternal antibodies will cross the placenta and attack the red blood cells of the fetus if it is Rh-positive. The attack on fetal red blood cells will require blood transfusions for the fetus.
Rh factors are surface proteins found on red blood cells. An Rh-negative mother can be exposed to Rh-positive blood from the fetus in her first pregnancy. Without administration of Rh(o) D immunoglobulin during the delivery of her first baby, the mother can develop antibodies to Rh so that during her second pregnancy, the maternal antibodies will cross the placenta and attack the red blood cells of the fetus if it is Rh-positive. The attack on fetal red blood cells will require blood transfusions for the fetus.
← Didn't Know|Knew It →
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.
In an immune response to an organism like Neisseria, humans will often make use of antbodies. What is true of antibodies?
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.
In an immune response to an organism like Neisseria, humans will often make use of antbodies. What is true of antibodies?
Tap to reveal answer
The main function of bone marrow derived B-cells is to produce antibodies. T-cells are involved in helping the B-cell response, as well as participating in cell-mediated cytotoxicity.
The main function of bone marrow derived B-cells is to produce antibodies. T-cells are involved in helping the B-cell response, as well as participating in cell-mediated cytotoxicity.
← Didn't Know|Knew It →
One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Neutrophils are able to respond to the constant region of antibodies that coat foreign invaders. The neutrophil recognizes these antibodies, and ingests the pathogen they coated. Which of the following is true of antibodies?
One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Neutrophils are able to respond to the constant region of antibodies that coat foreign invaders. The neutrophil recognizes these antibodies, and ingests the pathogen they coated. Which of the following is true of antibodies?
Tap to reveal answer
Antibodies are a key component of adaptive immunity and occur in five main isotypes: IgA, IgD, IgE, IgG, and IgM. They are mainly composed of protein. Antibodies are produced by B-cells in response to a known antigen.
Antibodies are a key component of adaptive immunity and occur in five main isotypes: IgA, IgD, IgE, IgG, and IgM. They are mainly composed of protein. Antibodies are produced by B-cells in response to a known antigen.
← Didn't Know|Knew It →
Cholera is a disease caused by vibrio cholerae, a bacteria which enters the body through the digestive tract. The bacteria is absorbed by the small intestine and enters the blood stream. Which of the following antibodies would be most effective at preventing cholera?
Cholera is a disease caused by vibrio cholerae, a bacteria which enters the body through the digestive tract. The bacteria is absorbed by the small intestine and enters the blood stream. Which of the following antibodies would be most effective at preventing cholera?
Tap to reveal answer
Because V. cholerae enters the body through the digestive tract, the best antibody that can prevent infection would be one that is secreted into the small intestine. IgA is a secretory antibody that can be secreted by the cells lining the small intestine, into the small intestine lumen.
The other antibodies (IgG, IgM, IgD, and IgE) cannot be secreted out of the body and would only be effective once the V. cholerae has entered the body; therefore, IgA is the correct answer.
Because V. cholerae enters the body through the digestive tract, the best antibody that can prevent infection would be one that is secreted into the small intestine. IgA is a secretory antibody that can be secreted by the cells lining the small intestine, into the small intestine lumen.
The other antibodies (IgG, IgM, IgD, and IgE) cannot be secreted out of the body and would only be effective once the V. cholerae has entered the body; therefore, IgA is the correct answer.
← Didn't Know|Knew It →
Which of the following cell types secretes antibodies?
Which of the following cell types secretes antibodies?
Tap to reveal answer
B-cells are responsible for the humoral immune response, which is the production of antibodies in response to a specific antigen. T-cells mediate the adaptive immune response by helping to activate B-cells (helper T-cells) and attacking foreign pathogens (cytotoxic T-cells). Natural killer cells are part of the innate immune response, and kill infected or damaged cells. Macrophages and neutrophils are phagocytes and help to attack and digest pathogens.
B-cells are responsible for the humoral immune response, which is the production of antibodies in response to a specific antigen. T-cells mediate the adaptive immune response by helping to activate B-cells (helper T-cells) and attacking foreign pathogens (cytotoxic T-cells). Natural killer cells are part of the innate immune response, and kill infected or damaged cells. Macrophages and neutrophils are phagocytes and help to attack and digest pathogens.
← Didn't Know|Knew It →
Which part of the antibody recognizes the antigen?
Which part of the antibody recognizes the antigen?
Tap to reveal answer
The antibody has two light chains and two heavy chains, each with a constant and a variable region. The variable regions of each chain are randomized during cell proliferation and recognize different antigens. This provides diversity of recognition for a better immune system.
The antibody has two light chains and two heavy chains, each with a constant and a variable region. The variable regions of each chain are randomized during cell proliferation and recognize different antigens. This provides diversity of recognition for a better immune system.
← Didn't Know|Knew It →
Which of the following statements is false concerning the humoral immune system?
Which of the following statements is false concerning the humoral immune system?
Tap to reveal answer
Memory B-cells proliferate and remain in the body for great periods of time following an infection. These cells are used to respond to infections that have been previously seen by the immune system. They create antibodies for a specific antigen previously seen by the body.
All other answers are true statements. Each antibody responds to only a single antigen, and each plasma cell synthesizes only one type of antibody. B-cells differentiate into plasma cells when presented with a new antigen. Dendritic cells often act to present such antigens to T-cells and B-cells.
Memory B-cells proliferate and remain in the body for great periods of time following an infection. These cells are used to respond to infections that have been previously seen by the immune system. They create antibodies for a specific antigen previously seen by the body.
All other answers are true statements. Each antibody responds to only a single antigen, and each plasma cell synthesizes only one type of antibody. B-cells differentiate into plasma cells when presented with a new antigen. Dendritic cells often act to present such antigens to T-cells and B-cells.
← Didn't Know|Knew It →
A patient is admitted to the hospital needing a blood transfusion. The patient has type A negative blood. Which of the following is true?
A patient is admitted to the hospital needing a blood transfusion. The patient has type A negative blood. Which of the following is true?
Tap to reveal answer
When looking at blood types, remember that the allele for blood type represents the type of antigen presented on the person's red blood cells. The positive or negative sign is indicative of whether or not the person makes Rh factors. If a person is negative, they create antibodies to positive Rh factors. If a person is missing an allele in their blood type, they will make antibodies for that particular antigen.
The patient in question will have antigens for type A, and antibodies against type B and Rh factor.
Type O negative blood means that there are no antigens on the red blood cells, meaning that a person with type A negative blood can receive type O negative blood. O negative blood is widely considered the "universal donor" type because it lacks any antigens that may react with antibodies in a recipient's blood. We cannot draw conclusions about the patient's parents; we know that one parent carried the A allele, but they could have been AB and the second parent could have been type O.
When looking at blood types, remember that the allele for blood type represents the type of antigen presented on the person's red blood cells. The positive or negative sign is indicative of whether or not the person makes Rh factors. If a person is negative, they create antibodies to positive Rh factors. If a person is missing an allele in their blood type, they will make antibodies for that particular antigen.
The patient in question will have antigens for type A, and antibodies against type B and Rh factor.
Type O negative blood means that there are no antigens on the red blood cells, meaning that a person with type A negative blood can receive type O negative blood. O negative blood is widely considered the "universal donor" type because it lacks any antigens that may react with antibodies in a recipient's blood. We cannot draw conclusions about the patient's parents; we know that one parent carried the A allele, but they could have been AB and the second parent could have been type O.
← Didn't Know|Knew It →
Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.
As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.
There are many ways that the body's immune system can attack its own tissues in autoimmune disease. A scientist discovers that in type 1 diabetes, antibodies play a key role in attracting lymphocytes to normal tissue, which is then damaged or destroyed. What kinds of cells typically produce antibodies?
I. T-cells
II. B-cells
III. Macrophages
Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.
As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.
There are many ways that the body's immune system can attack its own tissues in autoimmune disease. A scientist discovers that in type 1 diabetes, antibodies play a key role in attracting lymphocytes to normal tissue, which is then damaged or destroyed. What kinds of cells typically produce antibodies?
I. T-cells
II. B-cells
III. Macrophages
Tap to reveal answer
B-cells are the only cells to produce antibodies, which then target pathogens (or normal tissue, in autoimmune disease) for phagocytosis or cell-killing via other immune pathways. T-cells mediate the adaptive immune response and activation of B-cells, but do not produce antibodies. Macrophages help to phagocytose foreign particulates and pathogens, and can react to the antigens or antibodies attached to a foreign pathogen, but do not produce antibodies.
B-cells are the only cells to produce antibodies, which then target pathogens (or normal tissue, in autoimmune disease) for phagocytosis or cell-killing via other immune pathways. T-cells mediate the adaptive immune response and activation of B-cells, but do not produce antibodies. Macrophages help to phagocytose foreign particulates and pathogens, and can react to the antigens or antibodies attached to a foreign pathogen, but do not produce antibodies.
← Didn't Know|Knew It →
Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.
As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.
A doctor discovers that a newborn baby has a rare infection of her lungs. He does an analysis of the baby's blood and finds a near-total lack of antibodies in the plasma. The remainder of her immune system is intact. In which of the numbered arrows of the given figure is there most likely to be a breakdown in normal functioning?
Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.
As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.
A doctor discovers that a newborn baby has a rare infection of her lungs. He does an analysis of the baby's blood and finds a near-total lack of antibodies in the plasma. The remainder of her immune system is intact. In which of the numbered arrows of the given figure is there most likely to be a breakdown in normal functioning?
Tap to reveal answer
The lack of antibodies indicates a failure of B-cell maturation, as B-cells are the only cells to produce antibodies. B-cells, as the passage indicates, are sent from the bone marrow directly into the circulation via arrow 2; thus, a breakdown in this process would be expected to lead to a loss of antibodies in the blood. Because the question states that the rest of the immune system is intact, we can assume that T-cell maturation is unaffected in the patient, meaning that arrows 1 and 3 are not affected.
The lack of antibodies indicates a failure of B-cell maturation, as B-cells are the only cells to produce antibodies. B-cells, as the passage indicates, are sent from the bone marrow directly into the circulation via arrow 2; thus, a breakdown in this process would be expected to lead to a loss of antibodies in the blood. Because the question states that the rest of the immune system is intact, we can assume that T-cell maturation is unaffected in the patient, meaning that arrows 1 and 3 are not affected.
← Didn't Know|Knew It →
Major histocompatibility complex (MHC) II molecules are responsible for displaying antigens from what invading pathogen?
Major histocompatibility complex (MHC) II molecules are responsible for displaying antigens from what invading pathogen?
Tap to reveal answer
The "self" antigens that prevent T-cells from attacking the body are called MHC molecules. These molecules come in two classes: class I and class II. RNA, DNA, and proteins from bacteria are displayed after the bacterium is ingested by an antigen-presenting cell using MHC class II molecules. The antigen-presenting cell reports the MHC molecule corresponding to the bacteria to a helper T-cells. Once the helper T-cells see this unrecognized part of the bacterium, and detect it as different from "self," they can initiate the adaptive immune response.
The "self" antigens that prevent T-cells from attacking the body are called MHC molecules. These molecules come in two classes: class I and class II. RNA, DNA, and proteins from bacteria are displayed after the bacterium is ingested by an antigen-presenting cell using MHC class II molecules. The antigen-presenting cell reports the MHC molecule corresponding to the bacteria to a helper T-cells. Once the helper T-cells see this unrecognized part of the bacterium, and detect it as different from "self," they can initiate the adaptive immune response.
← Didn't Know|Knew It →
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
Before antibodies enter into circulation, they exist as B-cell receptors (BCRs). BCRs are transmembrane proteins that are identical to the antibodies that exist in free circulation, with the exception of one component. Which component is likely present in BCRs, but not in antibodies in solution with blood?
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
Before antibodies enter into circulation, they exist as B-cell receptors (BCRs). BCRs are transmembrane proteins that are identical to the antibodies that exist in free circulation, with the exception of one component. Which component is likely present in BCRs, but not in antibodies in solution with blood?
Tap to reveal answer
A B-cell receptor (BCR) is a transmembrane protein, and thus must have an integral membrane domain consisting of hydrophobic amino acids. This is different from antibodies in solution, which would likely not have such an integral membrane domain. The mature antibody must be capable of being in the aqueous blood solution. The persistence of a hydrophobic region in the antibody would inhibit its solubility in the blood, reducing its functionality.
A B-cell receptor (BCR) is a transmembrane protein, and thus must have an integral membrane domain consisting of hydrophobic amino acids. This is different from antibodies in solution, which would likely not have such an integral membrane domain. The mature antibody must be capable of being in the aqueous blood solution. The persistence of a hydrophobic region in the antibody would inhibit its solubility in the blood, reducing its functionality.
← Didn't Know|Knew It →
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
A patient presents to their local primary care clinic with a 1-day old influenza infection. Their blood is drawn and analyzed for antibodies. Four months after the infection, their physician draws their blood again and studies the presence of antibodies. Which of the following is most likely to be true?
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
A patient presents to their local primary care clinic with a 1-day old influenza infection. Their blood is drawn and analyzed for antibodies. Four months after the infection, their physician draws their blood again and studies the presence of antibodies. Which of the following is most likely to be true?
Tap to reveal answer
Antibodies are part of the adaptive immune response. As a result, we would expect that their concentration during an acute infection would be lower than their concentration in a post-infection (convalescent) serum sample. In fact, many diagnostic assays use this phenomenon to confirm diagnoses.
Antibodies are among the major immune responses to viral infections, especially influenza.
Antibodies are part of the adaptive immune response. As a result, we would expect that their concentration during an acute infection would be lower than their concentration in a post-infection (convalescent) serum sample. In fact, many diagnostic assays use this phenomenon to confirm diagnoses.
Antibodies are among the major immune responses to viral infections, especially influenza.
← Didn't Know|Knew It →
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
Unlike B-cells, T-cells do not make antibodies. T-cells are important in the execution of cytotoxic immunity, such as neutralizing virus-infected cells. A scientist is studying the T-cell response in a mammal, and finds that his CD8+ T-cells are interacting with a surface protein found on many different types of cells in his model organism. This protein is most likely .
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
Unlike B-cells, T-cells do not make antibodies. T-cells are important in the execution of cytotoxic immunity, such as neutralizing virus-infected cells. A scientist is studying the T-cell response in a mammal, and finds that his CD8+ T-cells are interacting with a surface protein found on many different types of cells in his model organism. This protein is most likely .
Tap to reveal answer
Major histocompatibility complex (MHC) class I is found on all nucleated cell types, while MHC class II is limited to antigen-presenting cells, such as dendritic cells. MHC class I presents foreign antigens from intracellular parasites to CD8+ T-cells in an effort to demonstrate infection and initiate cell killing.
C-C chemokine receptor type 5 (CCR5) is a specific chemokine receptor on the surface of T-cells, and is involved in cell recruitment to initiate the immune response. CD28 ligand is expressed by antigen-presenting cells and binds to T-cell receptors to activate T-cells. Interleukin-2 (IL-2) is a cytokine secreted into the blood to help activate the T-cell immune response.
Major histocompatibility complex (MHC) class I is found on all nucleated cell types, while MHC class II is limited to antigen-presenting cells, such as dendritic cells. MHC class I presents foreign antigens from intracellular parasites to CD8+ T-cells in an effort to demonstrate infection and initiate cell killing.
C-C chemokine receptor type 5 (CCR5) is a specific chemokine receptor on the surface of T-cells, and is involved in cell recruitment to initiate the immune response. CD28 ligand is expressed by antigen-presenting cells and binds to T-cell receptors to activate T-cells. Interleukin-2 (IL-2) is a cytokine secreted into the blood to help activate the T-cell immune response.
← Didn't Know|Knew It →
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
The readily reversible interactions between antigens and antibodies most probably use which of the following interactions?
I. Hydrogen bonding
II. Dipole-dipole interactions
III. Nonpolar covalent
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
The readily reversible interactions between antigens and antibodies most probably use which of the following interactions?
I. Hydrogen bonding
II. Dipole-dipole interactions
III. Nonpolar covalent
Tap to reveal answer
The interaction between pathogens and antibodies are non-covalent, and are comprised of weak intermolecular interactions. This question specifies that these interactions are reversible, which immediately eliminates covalent bonds as an option. Covalent bonding results in strong, long-term interaction on the atomic level. Dipole-dipole interactions and hydrogen bonding are more loose associations between full molecules, and can easily be broken in order for the molecules to dissociate.
The interaction between pathogens and antibodies are non-covalent, and are comprised of weak intermolecular interactions. This question specifies that these interactions are reversible, which immediately eliminates covalent bonds as an option. Covalent bonding results in strong, long-term interaction on the atomic level. Dipole-dipole interactions and hydrogen bonding are more loose associations between full molecules, and can easily be broken in order for the molecules to dissociate.
← Didn't Know|Knew It →
What component of the adaptive immune system binds to antibodies and allows for holes to be placed into bacterial cell membranes?
What component of the adaptive immune system binds to antibodies and allows for holes to be placed into bacterial cell membranes?
Tap to reveal answer
Once antibodies, produced by plasma cells, bind to the antigens on foreign bacteria or viruses, the complement system can begin to be assembled. The complement system is comprised of nine proteins that end up forming a pore in the membrane of bacteria and viruses, allowing other defense proteins to enter and destroying the sodium-potassium gradient that is required for energy generation in bacteria. Complement is also responsible for helping recruit immune cells to the site of infection or injury.
The major histocompatibility complex proteins are responsible for presenting antigens to helper T-cells.
Once antibodies, produced by plasma cells, bind to the antigens on foreign bacteria or viruses, the complement system can begin to be assembled. The complement system is comprised of nine proteins that end up forming a pore in the membrane of bacteria and viruses, allowing other defense proteins to enter and destroying the sodium-potassium gradient that is required for energy generation in bacteria. Complement is also responsible for helping recruit immune cells to the site of infection or injury.
The major histocompatibility complex proteins are responsible for presenting antigens to helper T-cells.
← Didn't Know|Knew It →
Major histocompatibility complex (MHC) I molecules primarily display antigens derived from what type of pathogen?
Major histocompatibility complex (MHC) I molecules primarily display antigens derived from what type of pathogen?
Tap to reveal answer
The "self" antigens that prevent T-cells from attacking the body are called MHC molecules. These molecules come in two classes: class I and class II. RNA, DNA, and proteins in viruses are displayed after the virus is ingested by an antigen-presenting cell using MHC class I molecules. The antigen-presenting cell reports the MHC molecule corresponding to the virus to a helper T-cells. Once the helper T-cells see this unrecognized part of the virus, and detect it as different from "self," they can initiate the adaptive immune response.
The "self" antigens that prevent T-cells from attacking the body are called MHC molecules. These molecules come in two classes: class I and class II. RNA, DNA, and proteins in viruses are displayed after the virus is ingested by an antigen-presenting cell using MHC class I molecules. The antigen-presenting cell reports the MHC molecule corresponding to the virus to a helper T-cells. Once the helper T-cells see this unrecognized part of the virus, and detect it as different from "self," they can initiate the adaptive immune response.
← Didn't Know|Knew It →
Blood types are designated A, B, AB, and O depending on the glycoprotein presented on the surface of the red blood cells. If a person has glycoproteins 
and 
. What is the person's blood type?
Blood types are designated A, B, AB, and O depending on the glycoprotein presented on the surface of the red blood cells. If a person has glycoproteins
Tap to reveal answer
The glycoproteins 
, 
, and 
are responsible for the A, B, and O blood types in humans, respectively.
and 
are dominant to 
, meaning that blood types A and B are dominant to O. Additionally, 
and 
can be co-dominant, giving the AB blood type. The person in the question has 
and 
glycoproteins, giving the patient the A blood type, as 
is dominant to 
. Genotypically, they will carry alleles for both A and O blood type, but their phenotype will be only A.
The glycoproteins
← Didn't Know|Knew It →
The receptor on the surface of a B-lymphocyte is a membrane-bound antibody. Which of the following is not a function of an antibody?
The receptor on the surface of a B-lymphocyte is a membrane-bound antibody. Which of the following is not a function of an antibody?
Tap to reveal answer
Antibodies are not responsible for the removal of pathogens, only the binding and/or tagging foreign materials for destruction by other immune cells. Antibodies are released into the blood stream and bind to matching antigens on the surface of infectious cells. By binding and tagging foreign materials, antibodies enhance the ability of other immune cells (such as macrophages) to engulf or phagocytose the foreign material, leading to its destruction and removal.
Antibodies themselves cannot remove pathogens; they only aid in the removal of pathogens by immune cells.
Antibodies are not responsible for the removal of pathogens, only the binding and/or tagging foreign materials for destruction by other immune cells. Antibodies are released into the blood stream and bind to matching antigens on the surface of infectious cells. By binding and tagging foreign materials, antibodies enhance the ability of other immune cells (such as macrophages) to engulf or phagocytose the foreign material, leading to its destruction and removal.
Antibodies themselves cannot remove pathogens; they only aid in the removal of pathogens by immune cells.
← Didn't Know|Knew It →
An influenza vaccination administered through injection would be categorized as what type of immunization?
An influenza vaccination administered through injection would be categorized as what type of immunization?
Tap to reveal answer
Active immunization is that which occurs as a result of the immune response of the affected individual. Passive immunization is the passing of antibodies from one entity to another, such as a pregnant mother who passes antibodies through the placenta to the fetus. Artificial immunization occurs when one is exposed to the antigen of the infection without having to experience the infection. The antigen can be a weakened or dead form of the microbe. Natural immunity is achieved when one is infected by a live form of the microbe. In both natural and artificial immunity, the immune system generates antibodies and memory cells to fight off future infections.
Active immunization is that which occurs as a result of the immune response of the affected individual. Passive immunization is the passing of antibodies from one entity to another, such as a pregnant mother who passes antibodies through the placenta to the fetus. Artificial immunization occurs when one is exposed to the antigen of the infection without having to experience the infection. The antigen can be a weakened or dead form of the microbe. Natural immunity is achieved when one is infected by a live form of the microbe. In both natural and artificial immunity, the immune system generates antibodies and memory cells to fight off future infections.
← Didn't Know|Knew It →