IB Biology Topic C3.2: Defense Against Disease Key Definitions

Antibiotic resistance occurs when bacteria evolve mechanisms to survive exposure to antibiotics that would normally kill them.

Antibiotics are chemical substances that kill or inhibit the growth of bacteria by targeting bacterial structures and processes that do not exist in human (eukaryotic) cells.

Foreign molecules, usually proteins or glycoproteins, that trigger an immune response by being recognized by the immune system.

White blood cells that recognize specific antigens and produce antibodies to neutralize pathogens.

Blood clotting is a rapid, highly coordinated response that transforms liquid blood into a semi-solid gel, sealing the wound. It prevents excessive blood loss from wounds and forms a protective barrier against pathogen entry.

The process of mitotic division that generates large numbers of B-cell clones, all capable of producing the same antibody.

Proteins in the blood that play a crucial role in the formation of blood clots.

Cytokines are small proteins that mediate and regulate immune responses, inflammation, and cell signaling

A disease is a disruption to the normal function or structure of the body, often caused by harmful microorganisms.

A soluble plasma protein that is converted into fibrin during clotting.

A protein with carbohydrate chains attached, which are involved in cell recognition, signalling, and adhesion.

A type of T lymphocyte (T cell) that helps activate B cells by providing necessary signals once both cells have recognized the same antigen.

A virus that attacks the immune system, leading to the eventual development of AIDS if untreated.

The ability of the body to defend against infections by recognizing and eliminating pathogens.

A general, non-specific response that does not change throughout life. It responds quickly to pathogens in a broad and generalized way

Lymphocytes are a type of white blood cell critical for the adaptive immune response.

Lysosomes are specialized vesicles containing digestive enzymes.

Pathogen refers to any organism or agent capable of causing disease.

The process by which phagocytes engulf and digest pathogens.

Differentiated B cells that produce and secrete large quantities of antibodies.

Small, disc-shaped cell fragments in the blood that help in clotting.

A faster and stronger immune response upon re-exposure to the same pathogen, mediated by memory cells.

An enzyme that converts fibrinogen to fibrin in the clotting process.

Vaccines are biological preparations that contain antigens or nucleic acids (DNA or RNA) from a pathogen.