Microbiology, 2021

E • Glossary 1185
cysts are formed to help the microbe
survive harsh conditions, whereas others
are a normal part of the life cycle
cytochrome oxidase final ETS complex
used in aerobic respiration that transfers
energy-depleted electrons to oxygen to
form H 2 O
cytokine storm an excessive release of
cytokines, typically triggered by a
superantigen, that results in unregulated
activation of T cells
cytokines protein molecules that act as a
chemical signals; produced by cells in
response to a stimulation event
cytokinesisdivision of the cytoplasm
following mitosis that forms two daughter
cells
cytomegalovirus (CMV) infection human
herpesvirus 5 infection that is typically
asymptomatic but can become serious in
immunocompromised patients, transplant
recipients, and developing fetuses
cytopathic effect cell abnormality
resulting from a viral infection
cytoplasm the gel-like material composed
of water and dissolved or suspended
chemicals contained within the plasma
membrane of a cell
cytoplasmic membrane see cell
membrane
cytoproct a protozoan cell structure that is
specialized for excretion
cytosine pyrimidine nitrogenous base
found in nucleotides
cytoskeleton a network of filaments or
tubules in the eukaryotic cell that provides
shape and structural support for cells; aids
movement of materials throughout the cell
cytostome a protozoan cell structure that
is specialized for phagocytosis (i.e., to take
in food)
cytotoxic T cells effector cells of cellular
immunity that target and eliminate cells
infected with intracellular pathogens
through induction of apoptosis
cytotoxicity harmful effects to host cell
D
dacryocystitis inflammation of the
lacrimal sac often associated with a
plugged nasolacrimal duct
daptomycin cyclic lipopetide that disrupts
the bacterial cell membrane
darkfield microscope a compound light
microscope that produces a bright image
on a dark background; typically a modified
brightfield microscope
death phase (decline phase) phase of the
growth curve at which the number of
dying cells exceeds the number of new
cells formed
decimal reduction time (DRT) or D-value
amount of time it takes for a specific
protocol to produce a one order of
magnitude decrease in the number of
organisms; that is, death of 90% of the
population
decolorizing agent a substance that
removes a stain, usually from some parts
of the specimen
deeply branching bacteria bacteria that
occupy the lowest branches of the
phylogenetic tree of life
definitive host the preferred host
organism for a parasite, in which the
parasite reaches maturity and may
reproduce sexually
degeneracy redundancy in the genetic
code because a given amino acid is
encoded by more than one nucleotide
triplet codon
degerming protocol that significantly
reduces microbial numbers by using mild
chemicals (e.g., soap) and gentle
scrubbing of a small area of skin or tissue
to avoid the transmission of pathogenic
microbes
degranulation release of the contents of
mast cell granules in response to the
cross-linking of IgE molecules on the cell
surface with allergen molecules
dehydration synthesis chemical reaction
in which monomer molecules bind end to
end in a process that results in the
formation of water molecules as a
byproduct
deletion type of mutation involving the
removal of one or more bases from a DNA
sequence
Deltaproteobacteria class of
Proteobacteria that includes sulfatereducing
bacteria
denatured protein protein that has lost its
secondary and tertiary structures (and
quaternary structure, if applicable)
without the loss of its primary structure
dendrites branched extensions of the
soma of a neuron that interact with other
cells
dengue fever mosquito-borne viral
hemorrhagic disease; also known as
breakbone fever
dental calculus calcified heavy plaque on
teeth, also called tartar
dental caries cavities formed in the teeth
as a result of tooth decay caused by
microbial activity
deoxyribonucleic acid (DNA) doublestranded
nucleic acid composed of
deoxyribonucleotides that serves as the
genetic material of the cell
deoxyribonucleotides DNA nucleotides
containing deoxyribose as the pentose
sugar component
dermatophyte any fungus of the genera
Microsporum, Epidermophyton, or
Trichophyton, which feed on keratin (a
protein found in skin, hair, and nails) and
can cause cutaneous infections
dermis the second layer of human skin,
found between the epidermis and the
hypodermis
descriptive epidemiology a method of
studying a disease outbreak using case
histories, contact interviews, medical
information, and other sources of
information
desensitization injections of antigen that
lead to production of antigen-specific IgG
molecules, effectively outcompeting IgE
molecules on the surface of sensitized
mast cells for antigen
desiccation method of microbial control
involving the removal of water from cells
through drying or dehydration
desquamation peeling and shedding of
outermost skin
diapedesis process by which leukocytes
pass through capillary walls to reach
infected tissue; also called extravasation
diaphragm a component of a microscope;
typically consists of a disk under the stage
with holes of various sizes; can be adjusted
to allow more or less light from the light
source to reach the specimen
differential interference-contrast
microscope a microscope that uses
polarized light to increase contrast
differential media media that contain