3.2.4 Cell Recognition and the Immune System

Question 1

Q: What specific molecules on the surface of cells enable the immune system to identify different types of cells?

Answer 1

A: Proteins on the surface of cells enable the immune system to identify different types of cells, including pathogens, cells from other organisms of the same species, abnormal body cells, and toxins.

Question 2

Q: What is an antigen?

Answer 2

A: An antigen is a molecule or part of a molecule that is recognized by the immune system as foreign, prompting an immune response.

Question 3

Q: How does antigen variability affect disease and disease prevention?

Answer 3

A: Antigen variability can allow pathogens to evade the immune system, making it difficult to prevent or treat diseases. It can also reduce the effectiveness of vaccines.

Question 4

Q: What is phagocytosis?

Answer 4

A: Phagocytosis is the process by which phagocytes (a type of immune cell) engulf and digest pathogens.

Question 5

Q: What role do lysozymes play in the immune system?

Answer 5

A: Lysozymes are enzymes that break down the cell walls of bacteria, leading to the destruction of ingested pathogens after phagocytosis.

Question 6

Q: What is the role of antigen-presenting cells in the cellular response?

Answer 6

A: Antigen-presenting cells process and present antigens on their surface to T cells, initiating the cellular immune response.

Question 7

Q: What is the cellular response in the immune system?

Answer 7

A: The cellular response involves T lymphocytes recognizing and responding to a foreign antigen.

Question 8

Q: What do helper T cells (TH cells) do in the immune response?

Answer 8

A: Helper T cells stimulate cytotoxic T cells (TC cells), B cells, and phagocytes, helping to coordinate the immune response.

Question 9

Q: What is the humoral response?

Answer 9

A: The humoral response involves B lymphocytes responding to a foreign antigen by producing antibodies, which neutralize or destroy the antigen.

Question 10

Q: What is clonal selection?

Answer 10

A: Clonal selection is the process by which a B lymphocyte that recognizes a specific antigen multiplies to produce a clone of cells that produce the same antibody.

Question 11

Q: What is an antibody?

Answer 11

A: An antibody is a protein produced by B cells that binds to a specific antigen to neutralize or destroy it.

Question 12

Q: Describe the structure of an antibody.

Answer 12

A: An antibody is typically Y-shaped, consisting of two heavy chains and two light chains, with variable regions that bind to specific antigens.

Question 13

Q: What is an antigen-antibody complex, and what does it lead to?

Answer 13

A: An antigen-antibody complex forms when an antibody binds to an antigen. This can lead to the destruction of the antigen through agglutination and phagocytosis of bacterial cells.

Question 14

Q: What is the role of plasma cells in the immune response?

Answer 14

A: Plasma cells are derived from B cells and produce large quantities of antibodies during the primary immune response.

Question 15

Q: What is the role of memory cells in the immune response?

Answer 15

A: Memory cells are long-lived B cells that remain in the body after an infection, providing a faster and more effective response if the same antigen is encountered again, leading to the secondary immune response.

Question 16

Q: How do vaccines provide protection against disease?

Answer 16

A: Vaccines stimulate the immune system to produce memory cells and antibodies against a specific pathogen, providing immunity without causing the disease.

Question 17

Q: What is herd immunity?

Answer 17

A: Herd immunity occurs when a large portion of a population becomes immune to a disease, reducing its spread and providing protection to individuals who are not immune.

Question 18

Q: What is the difference between active and passive immunity?

Answer 18

A: Active immunity occurs when the body produces its own antibodies in response to an infection or vaccine, while passive immunity is provided by transferring antibodies from another source, such as through maternal antibodies or antibody injections.

Question 19

Q: What is the structure of the human immunodeficiency virus (HIV)?

Answer 19

A: HIV is an enveloped virus with RNA as its genetic material. It has surface proteins, including gp120, which allows it to bind to and enter helper T cells.

Question 20

Q: How does HIV replicate in helper T cells?

Answer 20

A: HIV binds to CD4 receptors on helper T cells, enters the cell, and uses reverse transcriptase to convert its RNA into DNA, which integrates into the host cell’s genome, leading to the production of new virus particles

Question 21

Q: How does HIV cause the symptoms of AIDS?

Answer 21

A: HIV destroys helper T cells, weakening the immune system and making the body more susceptible to opportunistic infections and certain cancers, leading to AIDS.

Question 22

Q: How are monoclonal antibodies used to target medication to specific cell types?

Answer 22

A: Monoclonal antibodies can be designed to bind to specific antigens on target cells, delivering a therapeutic drug directly to those cells.

Question 23

Q: How are monoclonal antibodies used in medical diagnosis?

Answer 23

A: Monoclonal antibodies can be used to detect the presence of specific antigens in a sample, allowing for the diagnosis of diseases.

Question 24

Q: What are some ethical issues associated with the use of vaccines?

Answer 24

A: Ethical issues include concerns about vaccine safety, mandatory vaccination policies, and the use of certain ingredients in vaccines.

Question 25

Q: What are some ethical issues associated with the use of monoclonal antibodies?

Answer 25

A: Ethical issues include the potential for animal suffering in the production of monoclonal antibodies and the high cost of some monoclonal antibody therapies.

Question 26

Q: What is the ELISA test, and how is it used?

Answer 26

A: The ELISA test is used to detect the presence of specific antibodies or antigens in a sample. It involves binding an antigen or antibody to a surface, adding a sample, and then using a color change to indicate the presence of the target molecule.