immunobiology

Question 2

innate immune system?

Answer 2

The body’s first line of defense; non-specific, rapid, and includes physical barriers, chemical agents, and immune cells.

Question 3

adaptive immune system?

Answer 3

A specific immune defense that develops after exposure to antigens; includes B and T cells and forms immunological memory.

Question 4

thymus

Answer 4

A central lymphoid organ where T cells mature.

Question 5

bone marrow

Answer 5

A primary lymphoid organ where all immune cells originate and B cells mature.

Question 6

anatomical barriers?

Answer 6

Physical, chemical, and biological surfaces (like skin, mucosa, normal flora) that prevent pathogen entry.

Question 7

granulocytes?

Answer 7

White blood cells with granules (e.g., neutrophils, eosinophils) involved in the innate immune response.

Question 8

inflammation?

Answer 8

A protective immune response causing redness, swelling, and heat, aimed at eliminating pathogens and initiating repair.

Question 9

cellular immune response?

Answer 9

Mediated by T cells that attack infected cells directly.

Question 10

humoral immune response?

Answer 10

Involves B cells and antibodies circulating in body fluids.

Question 11

lymphoid organs?

Answer 11

Include central (thymus, bone marrow) and peripheral (lymph nodes, spleen) organs where lymphocytes mature and are activated.

Question 12

PAMPs?

Answer 12

Molecules found on pathogens but not on host cells, recognized by innate immune receptors.

Question 13

pattern recognition receptors (PRRs)?

Answer 13

Receptors that detect PAMPs and trigger innate immune responses.

Question 14

TLR?

Answer 14

A type of PRR that activates inflammation and helps initiate adaptive immunity.

Question 15

hematopoietic stem cells (HSCs)?

Answer 15

Self-renewing stem cells in bone marrow that give rise to all blood cells.

Question 16

lymphoid progenitor cells?

Answer 16

Stem cells that develop into B cells, T cells, and NK cells.

Question 17

What are myeloid progenitor cells?

Answer 17

Stem cells that develop into granulocytes, monocytes, macrophages, and others.

Question 18

What is hematopoiesis?

Answer 18

The process of blood cell formation in the bone marrow.

Question 19

What are central lymphoid organs?

Answer 19

Sites of lymphocyte development (bone marrow and thymus).

Question 20

What are peripheral lymphoid organs?

Answer 20

Sites where mature lymphocytes encounter antigens (e.g., lymph nodes, spleen).

Question 21

What are cytotoxic T cells?

Answer 21

T cells that kill virus-infected or cancerous cells.

Question 22

What are helper T cells?

Answer 22

T cells that assist other immune cells by secreting cytokines.

Question 23

What are regulatory T cells?

Answer 23

T cells that suppress immune responses and maintain tolerance to self-antigens.

Question 24

What are B cells?

Answer 24

Lymphocytes that produce antibodies.

Question 25

What are lymphocytes?

Answer 25

White blood cells including B cells, T cells, and NK cells.

Question 26

What is the Clonal Selection Theory?

Answer 26

Each lymphocyte is specific to a single antigen; upon activation, it proliferates and forms clones.

Question 27

What is an epitope?

Answer 27

The specific part of an antigen recognized by a B or T cell receptor.

Question 28

What is an immunodominant epitope?

Answer 28

An epitope that elicits the strongest immune response among many.

Question 29

What is immunological memory?

Answer 29

The adaptive immune system’s ability to respond faster and more effectively upon re-exposure to an antigen.

Question 30

What are memory cells?

Answer 30

Long-lived B or T cells that “remember” past infections.

Question 31

What is immunological tolerance?

Answer 31

Mechanisms that prevent the immune system from attacking the body’s own cells.

Question 32

What is an antibody?

Answer 32

A Y-shaped protein made by B cells that binds to specific antigens to neutralize or mark them for destruction.

Question 33

What is an antigen?

Answer 33

Any substance that triggers an immune response, especially one that binds to an antibody or TCR.

Question 34

What are the classes of antibodies?

Answer 34

IgM, IgG, IgA, IgD, and IgE—each has unique roles in immunity.

Question 35

What is B cell development?

Answer 35

Stages from stem cell to mature B cell, involving Ig gene rearrangement and selection.

Question 36

What are the components of an antibody?

Answer 36

Antibodies consist of two heavy chains and two light chains forming the antigen-binding site.

Question 37

What are the constant and variable regions of an antibody?

Answer 37

Variable regions bind antigens; constant regions determine antibody class and function.

Question 38

What are Ig domains?

Answer 38

Structural units of antibodies (~110 amino acids) that fold into a stable domain.

Question 39

What is antibody diversity?

Answer 39

The wide variety of antibodies generated through V(D)J recombination, somatic hypermutation, and class switching.

Question 40

What is the primary antibody repertoire?

Answer 40

The diverse set of IgM/IgD antibodies made before antigen exposure.

Question 41

What is the secondary antibody repertoire?

Answer 41

More diverse antibodies formed after antigen exposure, includes IgG, IgA, and IgE.

Question 42

What is combinatorial diversification?

Answer 42

Combining different V, D, and J gene segments to increase antibody diversity.

Question 43

What is somatic hypermutation?

Answer 43

Point mutations in antibody genes that increase affinity after antigen stimulation.

Question 44

What is class switching?

Answer 44

Changing antibody class (e.g., from IgM to IgG) without changing antigen specificity.

Question 45

What is activation-induced deaminase (AID)?

Answer 45

An enzyme essential for somatic hypermutation and class switching.

Question 46

What is affinity maturation?

Answer 46

Selection of B cells with the highest-affinity antibodies after repeated antigen exposure.

Question 47

What are germinal centers?

Answer 47

Sites in lymphoid organs where B cells proliferate, mutate, and are selected.

Question 48

What is a T receptor (TCR)?

Answer 48

Receptor on T cells that recognizes antigen peptides presented on MHC molecules.

Question 49

What are MHC proteins?

Answer 49

Present antigen fragments to T cells. Class I MHC presents to cytotoxic T cells; Class II to helper T cells.

Question 50

What are antigen-presenting cells (APCs)?

Answer 50

Cells like dendritic cells, macrophages, and B cells that present antigens on MHC proteins to T cells.

Question 51

What is MHC-I?

Answer 51

Found on nearly all cells; presents intracellular antigens to cytotoxic T cells.

Question 52

What is MHC-II?

Answer 52

Found mainly on APCs; presents extracellular antigens to helper T cells.

Question 53

What are dendritic cells?

Answer 53

Professional APCs that activate naive T cells and initiate adaptive responses.