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micro exam 2
micro exam 2 11-4-11
50
Microbiology
Not Applicable
11/02/2011

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Term
Axial filaments
Definition
Seen in spirochetes. These are like
flagellum but are enclosed within a sheath surrounding the cell.
Term
Gram-positive cell walls consist of
Definition
many layers of
peptidoglycan and contain lipoteichoic acids.
Term
Gram-negative bacteria have a
Definition
lipoprotein-
Lipopolysaccharide-phospholipid outer membrane surrounding a thin peptidoglycan layer
Term
Outer membrane protects gram- negative cells from
Definition
phagocytosis, penicillin, lysozymes, and other chemicals
Term
Non-selective media
Definition
one that contains general nutrients needed to
sustain a wide variety of microorganisms. These can be in fluid form (often called broth), or solid form which is broth containing agar. The latter is like “Jello”.
Term
Differential media
Definition
in addition to general nutrients, it contains other
ingredients which produce visual differentiation between microorganisms. An example is blood in the medium that allows various types of streptococci to leave different signs on the agar surface, eg. green discoloration around colonies indicates alpha-hemolytic streptococci, a clear zone signifies beta-hemolysis, and no effect denotes gamma-hemolysis.
Term
Selective media
Definition
These contain ingredients such as dyes or antibiotics
which prevent growth of certain microorganisms while permitting others to grow. An example is Sabouraud dextrose agar which is selective for fungi.
Term
Most bacteria reproduce via
Definition
binary fission (i.e., two new cells are
produced by one parent cell). Duplicates of the cell constituents form at either end of a single cell which then separates into 2 cells by in-growth of the cell membrane and wall.
Term
Growth curve
Definition
. 1) Lag phase—period of intense metabolic activity but no increase in cell number. 2) Log phase or exponential growth phase—cell number increases in an exponential manner; generation time is the average time for the cell to divide. 3) Stationary phase-total number of viable cells is constant; metabolic activity slows. 4) Phase of decline or death phase - number of viable cells decreases.
Term
Measurement of growth
Definition
Population counts—cell numbers cab be measured by viable plate
counts (number of colonies on an agar medium). Counts are expressed as colony-forming units (CFU) for bacteria or plaque-forming units (PFU) for viruses. (Viruses are inoculated on an agar medium containing a dense lawn of live cells or bacteria on the surface. Where viruses land they lyse these cells forming a clear plaque which can be seen and counted as the number of viral particles present.)
b. Cell mass can be measured by turbidity of culture in a liquid medium.
Term
Anabolism
Definition
Biosynthetic reactions that use energy in which
macromolecules such as nucleic acids, proteins, lipids, and polysaccharides are synthesized.
Term
Catabolism
Definition
degradative reactions that release energy when
complex compounds are broken down into smaller units .
Term
Transcription
Definition
synthesis of messenger RNA (mRNA) from
DNA template.
Term
Translation
Definition
synthesis of protein in the ribosomes from an
mRNA template.
Term
Conjugation
Definition
a. Transfer of genetic material between two living bacteria that are in
physical contact.
b. Plasmids are most frequently transferred
Term
Transduction
Definition
a bacterial virus (bacteriophage) transfers genetic
material to another bacterium
Term
Transformation
Definition
the direct uptake of donor DNA by a recipient cell
Term
Transposons
Definition
jumping genes” small segments of DNA that can move
from one region of a chromosome to another region of the genome.
Term
Classification of infections
Definition
a. Systemic—can affect a number of tissues and organs
b. Subcutaneous—beneath the skin
c. Cutaneous (superficial, Tinea infections
d. Opportunistic—generally harmless, but can become pathogenic in
a debilitated host.
Term
inflammatory reaction
Definition
 PMNs and macrophages engulf and destroy foreign particles or cells, mast cells and basophils release histamine at the damaged tissue which cause acute inflammation, Histamines cause capillaries to leak, releasing phagocytes, platelets move out of capillary to seal the wounded area
Term
lgG
Definition
secondary immune response. Its the only immunoglobulin capable of crossing placenta barriers.
Term
lgM
Definition
primary immune response.
Term
lgA
Definition
tears, saliva. bile, urine, and colostrum
Term
lgE
Definition
immediate hypersensitivity reactions. It binds to mast cells where it activates them to release histamine
Term
Type l
Definition
. Anaphylactic (" immediate") hypersensitivity: lgE mast and basophil cells release large amounts of histamine Examples asthma attacks, hay fever, hives, anaphylactic shock
Term
Type ll.
Definition
Cytolytic hypersensitivity. example is a mother’s immune system destroying her baby’s red blood cells
Term
Type lll. lmmune complex hypersensitivity:
Definition
Too many antigen-antibody immune complexes are deposited in tissues. Examples are serum sickness and arthus reactions
Term
Type lV. Delayed hypersensitivity:
Definition
T lymphocytes. Examples are contact dermatitis, poison ivy, graft rejection, tuberculin skin reaction
Term
Antibody (Ab)
Definition
a protein that is produced as a result of the introduction of a foreign antigen and has the ability to combine with the antigen that stimulated its production.
Term
Antigen( Ag)
Definition
a non-self substance that can induce a detectable immune response when introduced into a living host.
Term
B-cell ( also B –lymphocyte)
Definition
B –cells are the precursors of plasma cells that produce antibody.
Term
Chemotaxis
Definition
a process whereby phagocytic cells are attracted to the vicinity of invading pathogens.
Term
Complement
Definition
A complex group of serum proteins which makes holes in the membranes of bacteria or sometimes host cells killing them. It works only if an antibody is attached to the foreign body or cell.
Term
Cytokines
Definition
are small proteins secreted by host defense cells (mainly lymphocytes) that act as signaling agents to other cells. In Immunity, cytokines activate other cells to destroy or inhibit a foreign agent or cell in the body or stimulate elements of the immune systems.
Term
Cytolysis
Definition
the lysis of bacteria or of cells such,as tumor or red blood cells by the membrane attack complex derived from activated complement or immune cells.
Term
Histocompatible
Definition
having the same antigens as the self-antigens
Term
lmmune response
Definition
development of resistance (immunity) to a foreign substance ( e.g. infectious agent); it can be antibody mediated (humoral) cell mediated (cellular), or both.
Term
lmmunoglobulin
Definition
a glycoprotein molecule that may function as an antibody. All antibodies are immunoglobulins, but not all immunoglobulins have antibody function.
Term
lmmunodeficiency
Definition
Inability of the immune system to perform normally and often results in increased susceptibility to infection. Example: Drug – induced immunosuppression
Term
Interferon
Definition
low molecular-weight proteins elaborated by viral-infected host cells that protect non-infected cells from viral infection.
Term
Lymphocyte
Definition
a “white blood cell” that includes the T-cells and B-cells which have primary roles in immunity.
Term
Macrophage
Definition
a phagocytic cell derived from the mononuclear cell or monocyte (a white blood cell) found in the blood. In inflammation the monocytes exit from blood vessles and become macrophages in the tissue. Macrophages also have roles in humoral and cellular immunity.
Term
Major histocompatibility complex (MHC)
Definition
a cluster of genes located in close proximity that determines histocompatibility antigens for members of a species. These antigens become the “self” labels.
Term
Monocyte
Definition
a circulating phagocytic blood cell that develops into tissue macrophages
Term
Opsonin
Definition
a substance capable of enhancing phagocytosis; eg. antibodies.
Term
Opsonization
Definition
the coating of an antigen or particle ( e.g., infectious agent) by substances such as antibodies, that facilitate uptake of the foreign particle into a phagocytic cell.
Term
Polymorphonuclear cell (PMN)
Definition
also known as a neutrophil or granulocyte, a PMN is characterized by a multilobed nucleus; PMNs migrate from the circulation to a site of inflammation by chemotaxis and are phagocytic for bacteria and other foreign particles. It is part of the innate immune system.
Term
T-cell (also T-lymphocyte)
Definition
A defense cell that participates in a variety of cell-mediated immune reactions
Term
TH (helper) or CD4 cell
Definition
A T-lymphocyte which has a molecular marker on its surface called “CD4” and functions to help or accommodate immune reactions such as sensitization of T or B lymphocytes by antigens.
Term
Ts (suppressor) or CD8 cell
Definition
A T-lymphocyte which has a molecular marker on its surface called “CD8” and functions to suppress excessive immune reactions. The helper and suppressor T cells act in unison to modulate or control immunity.
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