Microbiology Review Flashcards

Questions and Answers

Distinguish between an antigen and an antibody.

An antigen is a molecule that stimulates an immune response whereas an antibody is a protein made in response to an antigen.

What is immunity?

The ability of an organism to resist a particular infection or toxin by the action of specific antibodies or sensitized white blood cells.

Differentiate between agglutination, opsonization, and neutralization.

Agglutination enhances phagocytosis and reduces the number of infectious units, opsonization coats the antigen with antibody to enhance phagocytosis, and neutralization blocks the adhesion of bacteria and viruses.

What are the four main types of T cells?

Helper T cells Signup and view all the answers

Explain why the immune system does not react to the body's own cells.

Antigens are produced in response to foreign cells; the body recognizes its own cells and does not attack them. Signup and view all the answers

What is the function of MHC molecules?

MHC molecules bind peptide fragments from pathogens to the surface of infected cells for recognition by T-cells. Signup and view all the answers

Distinguish between plasma and memory B cells.

Plasma cells produce the first wave of antibodies, while memory B cells remember the infection to respond quickly in the future. Signup and view all the answers

Explain the Clonal Selection theory and its application to B cells.

The theory explains how B cells quickly respond to a pathogen upon second exposure, with memory B cells remaining after the infection to facilitate a quicker response. Signup and view all the answers

Describe how a T cell is activated by a macrophage that has encountered a bacterial cell.

A T cell is activated when a macrophage displaying the antigen on its MHC proteins fits the T cell's antigen receptor. Signup and view all the answers

Illustrate the primary and secondary immune response of IgG to a vaccine.

Primary response occurs after the first vaccine exposure with a lag phase, while the secondary response is faster and stronger due to memory B cells. Signup and view all the answers

Distinguish between antibody-mediated immunity and cell-mediated immunity.

Antibody-mediated immunity involves B cells and the production of antibodies, whereas cell-mediated immunity occurs when pathogens invade the body’s cells. Signup and view all the answers

Study Notes

Antigens and Antibodies

Antigens stimulate an immune response; antibodies are proteins produced in response to antigens.
Antibodies can recognize and bind to specific antigens.

Immunity

Immunity is the ability to resist infections or toxins through specific antibodies or sensitized white blood cells.

Agglutination, Opsonization, and Neutralization

Agglutination: Enhances phagocytosis by clumping pathogens, reducing the number of infectious units.
Opsonization: Coats antigens with antibodies to promote phagocytosis.
Neutralization: Blocks bacteria and viruses from adhering to cells and inhibits toxins.

Types of T Cells

Helper T cells
Cytotoxic T cells
Memory T cells
Suppressor T cells

Self-Tolerance in the Immune System

The immune system does not attack the body’s own cells because it recognizes self-antigens versus foreign antigens.
This prevents the body from launching an attack against its own cells.

Major Histocompatibility Complex (MHC)

MHC molecules bind peptide fragments from pathogens and display them on cell surfaces for T-cell recognition.
They are crucial for mediating interactions between pathogens and leukocytes, essential to the acquired immune response.

Plasma B Cells vs. Memory B Cells

Plasma cells are derived from B cells and produce the first wave of antibodies against infections.
Memory B cells retain information about the infection for a quicker response in future encounters.

Clonal Selection Theory and B Cells

Clonal Selection Theory explains the rapid response of the immune system upon re-exposure to pathogens.
B cells can clone themselves into plasma cells and memory B cells, with memory B cells remaining for faster responses in future infections.

T Cell Activation by Macrophages

T cell activation needs an antigen-presenting cell like a macrophage displaying the antigen on MHC proteins.
Helper T cells bind to the right antigen, leading to their activation, while memory T cells ensure a rapid response to future exposures.

Primary and Secondary Immune Response of IgG

IgG provides protection against pathogens and toxins, first produced upon initial exposure.
The primary response shows a lag phase as B cells differentiate; the secondary response is quicker due to existing memory B cells, resulting in higher levels and longer duration of antibodies.

Antibody-Mediated vs. Cell-Mediated Immunity

Antibody-mediated (Humoral) immunity involves B cells binding to antigens, assisted by helper T cells, leading to plasma cell differentiation and antibody production.
Cell-mediated immunity is triggered when a pathogen invades body cells, leading to direct attacks from T cells.

Description

Test your knowledge of key microbiology concepts with these flashcards. This quiz covers essential terms such as antigens, antibodies, and immunity, helping you reinforce your understanding in preparation for exams.