BIOLOGY II MIDTERM 1 STUDY GUIDE WITH
SOLVED QUESTIONS
◉B cells. Answer: lymphocytes that remain in bone marrow in
process of maturation
◉T cells. Answer: lymphocytes that migrate to thymus
◉antigen. Answer: any foreign substance that elicits a B or T cell
response; most are proteins or large polysaccharides
◉epitope. Answer: specific region that is exposed on the surface of
antigen molecule; binds to antigen receptor; each B and T cell
displays specificity for a specific epitope
◉transmembrane region of receptor. Answer: near one end of heavy
chain; anchors receptor in B cell's plasma membrane
◉constant region. Answer: portions of light and heavy chains; amino
acid sequences vary little among B cells
,◉variable region. Answer: found within tips of Y shape; each tip is
binding site for antigen; each receptor has 2 identical antigen
binding sites
◉B cell classes. Answer: IgA, IgD, IgE, IgG, and IgM
◉B cell activation. Answer: activation begins when a B cell antigen
receptor (tips) binds to antigen; leads to formation of cells that
secrete soluble form of receptor (antibodies = immunoglobin)
◉antibodies. Answer: have same y-shaped structure as B cell
antigen receptors; not membrane bound; do actual defense against
pathogens
◉T cell antigen receptors. Answer: bind only to fragments of antigen
that are displayed on surface of host cell
◉host cell. Answer: characterized by major histocompatibility
complex (MHC) molecules; host protein that displays antigen
fragment on cell surface
◉4 major characteristics of adaptive immunity. Answer: B and T cell
diversity, self-tolerance, proliferation of B and T cells, and
immunological memory
,◉self-tolerance. Answer: ability to distinguish between self (own
cells) vs non-self (foreign matter); organisms are biochemically
unique, all individual's cells have different surface proteins
◉proliferation of B and T cells. Answer: once specific cell is activated
(B or T) it undergoes multiple cell divisions
◉clonal selection. Answer: making clones
◉effector cells. Answer: take effect immediately, short lived
◉plasma cells. Answer: effector forms of B cells
◉helper T cells and cytotoxic T cells. Answer: effector forms of T
cells
◉memory cells. Answer: long lived, ready to divide if same antigen
appears again; if antigen does appear again, they give rise to effector
cells
◉immunological memory. Answer: long term protection that occurs
from prior infection; result of B and T memory cells
, ◉humoral response. Answer: occurs in blood and lymph by
antibodies
◉cell-mediated response. Answer: infected host cells destroyed by
specialized T cells
◉helper T cells. Answer: triggered by antigen display on surface of
APC; trigger humoral and cell-mediated responses; produce signals
that initiate antibody production; signals activate T cells and kill
infected cells
◉types of APC's. Answer: dendritic cell, macrophage, B cell
◉CD4. Answer: accessory protein found on helper T cell surface;
binds to class II MHC molecule; keeps cells joined (helper T cell and
antigen)
◉cytotoxic T cells. Answer: use toxic proteins to kill cells infected by
viruses or other intracellular pathogens (accomplished before
pathogen matures); activated by signals from helper T cells and
interaction with APC
◉perforin. Answer: released by cytotoxic T cells; forms pores in
infected cells plasma membrane