UNIT 4 Flashcards
Disease
any condition that affects the
normal function of either a part of an organism or the complete organism
Non-infectious
(noncommunicable)
disease
a disease that cannot be transmitted
from one organism to another
Infectious
(communicable)
disease
a disease that can be transmitted from one organism to another
Pathogen
a disease-causing agent
Epidemic
the rapid spread of an infectious disease to a large number of people within a
population
Pandemic
an outbreak of infectious disease
that occurs over a wide geographical
area, affecting a large number of
people
Host
an organism that has been infected by a pathogen
Vector
a living organism that carries and transmits a pathogen from one organism to another
Antigen
a unique marker on the surface of
cells or viruses that is used in the identification of self from non-self
Self-antigen
an antigen on the surface of cells of an
organism that is identified by the immune
system as belonging to the organism and therefore does not trigger an immune
response
Non-self antigen
an antigen on the surface of cells of an organism that is identified by the immune system as foreign to the organism and triggers an immune response when
detected
MHC (major
histocompatibility
complex) marker
a protein that is found on the surface of cells and is used in the identification of pathogens in the immune response
Epitope
the specific region of an antigen that is recognised by the immune system
MHC Class I marker
a type of protein marker on the surface of all nucleated cells that assists in the identification of self from non-self
MHC Class II marker
a type of protein marker on antigen-presenting white
blood cells that is used in the activation of a specific immune response
Antigen-presenting cell (APC)
a specific type of white blood cell that uses
phagocytosis to engulf a pathogen before
displaying peptide fragments (epitopes) on its MHC Class II markers for detection by white blood cells
Allergen
any substance that causes an allergic reaction
Cellular pathogen
living organism that causes disease within a host
Bacteria
unicellular, prokaryotic
organisms that lack membrane-bound organelles
Tetanus
a bacterial disease characterised by
muscle stiffness and spasms
Spores (bacterial)
structures that bacteria form that aid in the survival of
the organism under adverse environmental conditions
Fungi
a wide variety of eukaryotic organisms that include
mushrooms, mould and yeasts
Terrestrial
describes any living organism
that lives or grows on land
Hyphae
long, branching filaments that extend off the main body of the fungus and secrete digestive enzymes
Mycelium
a collection of hyphae
Tinea
a common fungal infection that results in a red, flaky rash
in the area of the body that is affected
Rice blast disease
a fungal infection of rice that results in characteristic
lesions and spots throughout the plant’s shoot system
Protozoa
unicellular, eukaryotic organisms that belong to
the kingdom Protista; singular protozoan
Heterotrophic
describes any organism that obtains its nutrients by
feeding on organic matter
Cilia
short microtubule projections from
a cell that move to provide motility
(movement of the cell) or movement
of fluid
Malaria
a serious disease caused by the
Plasmodium protozoan, which
invades red blood cells when
transmitted by mosquito vectors
into the host
Endemic
the usual area where an
organism is found
Non-cellular pathogen
a disease-causing agent that
lacks cellular structures and
cannot replicate outside a host
cell
Virus
a non-cellular pathogen that
causes disease by taking over host
cell machinery to rapidly produce
identical virus copies, which
further infect host cells,
disrupting normal cellular function
Virion
a single virus particle existing
outside a host cell
Capsid
protective protein coat that
surrounds the genetic material
of a virion
Viral envelope
the lipid-based, outermost layer
of the capsid on some types of
viruses
Dormant
when a virus is present within
the host but is inactive and
therefore not currently causing
symptoms associated with
the disease
Haemagglutinin
a glycoprotein embedded in the
viral envelope of the influenza
virus; plays an important role in
the attachment and entry of the
virus into the host cell
Neuraminidase
a glycoprotein embedded in the
viral envelope of the influenza virus; plays an important role in the detachment of new viral particles from the host cell, freeing them to infect new host cells
Epidemiology
a branch of medicine based on the study
of disease distribution and control
Plasmodesmata
microscopic channels that connect the cell
walls of plant cells, allowing communication and transport between the cells
Bacteriophage
a virus that specifically infects bacteria
Prion
a pathogenic protein with a mutant structure that can trigger normal proteins to fold abnormally, resulting in disease
PrPC
normal form of the protein associated with
prions
PrPSc
disease-causing, mutant prion
Innate response
a non-specific defence against
a pathogen
First line of defence
the first innate response; consists
of physical, chemical and microbiota
barriers
Normal flora
naturally occurring microorganisms
that live in or on animals and plants and do not cause harm or an immune response
Surfactants
molecules that reduce the
surface tension of water and
aqueous solutions
Saponin
soapy compound that occurs
naturally in plants; has anti-fungal and
antimicrobial properties
Defensins
proteins that are toxic to microbes
Blood–brain barrier
a barrier of specialised
epithelial cells in the brain
and spinal cord that prevents
pathogens and toxins reaching
the neurons
Pathogenic bacteria
bacteria that cause harm and an immune
response
Inflammatory response
heat, pain, redness, swelling and
loss of function as part of the innate immune
response to harmful stimuli
Mast cell
white blood cell involved in inflammatory
response, releasing histamine, triggering
inflammation
Histamine
compound released by
cells to start an inflammatory
response
Macrophage
large white blood cell that carries
out phagocytosis and may act
as an antigenpresenting cell
Cytokines
compounds released by cells as chemical
signals to other cells
Antigen-presenting cell
(APC)
a specific type of white blood
cell that uses phagocytosis to
engulf a pathogen
Lysis
breakdown of the cell membrane
Vasodilation
the widening of a blood vessel (especially
capillaries), to increase blood flow
Fever
a rise in body temperature caused by infection
Lymphocyte
a type of white blood cell; includes B and
T cells
Adaptive immune response
response of the vertebrate immune system
to a specific antigen, which typically
results in immunological memory
Interstitial fluid
fluid that collects in spaces between
cells and tissue
Lymph
colourless fluid that flows through
the lymphatic system
Lymphoid organ
organ involved in the production or function of
lymphocytes
Phagosome
a vesicle that engulfs a pathogen during phagocytosis
Neutrophil
white blood cell that carries out phagocytosis and kills pathogens with defensins
Dendritic cell
white blood cell with many folds and projections in its membrane, carries out phagocytosis and acts as an antigen-presenting cell to the adaptive immune system
Natural killer (NK) cell
white blood cell involved in innate immune response; kills infected host cells and cancer cells
Perforin
a protein that kills cells by making holes in their plasma membranes
Eosinophil
white blood cell that targets parasites
Phagocytosis
a type of endocytosis in which a solid substance enters a cell via vesicle mediated transport
Apoptosis
death and disintegration of a cell through a controlled process
Fever
a rise in body temperature caused by infection
Immunological memory
the ability of the immune system
to quickly and specifically recognise an
antigen that the body has previously
encountered and initiate a corresponding
immune response
Clonal selection theory
the scientific theory that a specific antigen
activates a specific lymphocyte
that has a complementary receptor
Naive
not yet activated
Antibody
a protein that has a Y shape containing
two identical arms with an antigen-binding
site specific to a antigen (or allergen); also
referred to as immunoglobulins (Ig)
Clonal expansion
the proliferation of a lymphocyte that has been selected by an antigen
Agglutination
where antibodies join to the pathogen’s
antigens, joining more than one pathogen
together
Effector cell
a cell that has been activated to perform its role
Active immunity
when an individual’s adaptive immune
response is activated
Passive immunity
short-term immunity resulting from a
person receiving antibodies from another person or animal; no memory
Vaccination
the administration of a vaccine to cause an adaptive immune response
Vaccine
substance that contains an agent (usually
an antigen or an attenuated version of the pathogen) that will induce an adaptive immune
response when administered
Attenuated
describes a pathogen that
has been altered to remove its
harmfulness
Herd immunity
when a large percentage of a population is
immune to a disease (through vaccination), slowing the spread of the disease and protecting those who are not immune
Disease
any condition that affects the normal function of either a part of an organism or the complete organism
Infection
when a pathogen has breached the first line of defence and begun to replicate
Virulence
how likely a pathogen is to cause harm/ disease
Contagious
describes a pathogen that is able to spread from an infected
person to others
Fatality
the occurrence of death
Epidemiologist
professional who studies the occurrence of diseases in a population
Infectious
able to be transmitted between hosts
Emerging infectious disease
a disease not yet seen in people, or a disease that is increasing in incidence or geographical range
Re-emerging infectious disease
a disease that appears again after having previously been eliminated
Indirect transmission
transmission of a pathogen from a location where it has been away from its host for a long time
Selection pressure
the conditions or factors that influence allele frequencies in a population by contributing to the selection of which phenotypes survive in a given environment,
e.g. availability of resources, environmental
conditions, predators and disease
Reservoir
original or usual
site of a disease
in relation to its
spread
Transmission
how a pathogen
is passed between hosts
Immunotherapy
a treatment that uses activation or suppression of the immune system
Monoclonal
antibody (mAb)
antibody made by cloning a unique parent
immune cell, produced in large
quantities in the laboratory as a drug targeting
specific cells or substances
Bispecific monoclonal antibody
a monoclonal antibody that has two different antigen-binding sites
Conjugated monoclonal
antibody
an antibody that has been combined with a radioactive substance or chemotherapy agent (a cytotoxin)
Myeloma cell
an abnormal plasma cell
used in the production of
monoclonal antibodies
Hybridoma
a cell that is a result of combining a B lymphocyte and a cancer cell
Genotype
the genetic make-up or the combination of alleles for a particular gene of an organism
Phenotype
a physical characteristic determined
by genotype and environment
Genetic diversity
the genetic variability within a species
Adaptations
the behavioural, physiological and structural features of an organism that help them survive in an environment
Population
a group of individuals of the same
species living in the same region at a given time
Species
a group of organisms that can interbreed,
producing fertile and viable offspring
Gene pool
the sum total of alleles present in a population of organisms
Allele frequency
the proportion of a particular allele within a
population
Evolution
a change in the allele frequencies of
a population over time
Mutation
a permanent change in the nucleotide
sequence of a section of DNA
Mutagenic agents
agents known to cause mutations;
for example, some radiation sources and
chemicals; also called mutagens
Point mutation
a change to one base in the nucleotide sequence of a section of DNA; includes base
substitutions and frameshift mutations
Substitution mutation
a type of point mutation that occurs when one nitrogenous base in a gene is replaced with another base; includes silent, missense and nonsense mutations
Silent mutation
a mutation where the change in the
nucleotide sequence doesn’t change
the amino acid that is coded for
Missense mutation
a mutation in which the base change in the
nucleotide sequence of the DNA changes the amino acid that is coded for; a type of substitution point mutation
Nonsense mutation
a mutation that occurs when the base change in the nucleotide sequence of the DNA codes for a STOP codon, prematurely halting the production of the polypeptide; a type of substitution point mutation
Frameshift mutation
a type of point mutation that occurs when
one base is inserted into or deleted from a
gene, causing an incorrect reading of the codons due to a shift in the reading frame
Block mutation
a type of mutation that affects large sections of DNA, typically containing multiple genes; also called chromosome mutation
Chromosome abnormality
mutation that involves a whole chromosome, or a change in the number of chromosomes,
which can be identified using a karyotype; examples are aneuploidy and polyploidy
Karyotype
a pictorial representation of chromosomes that allows a geneticist to determine size, banding pattern, shape and number of chromosomes in an individual’s somatic cell; allows the determination of diploid number, gender and chromosomal abnormalities
Aneuploidy
when a cell has one more or one less chromosome than expected, usually due to
non-disjunction
Polyploidy
a condition in which an organism has more than two full sets of chromosomes in its cells;
more common in plants than animals
Gene flow
the exchange of genetic information, specifically alleles, between populations
Genetic drift
a random change in allele frequency, occurring
naturally in every population, due to chance events
Bottleneck effect
when a population is drastically reduced to low
numbers by a random or chance event and the
allele frequencies of the surviving population do not reflect the genetic diversity of the original population
Founder effect
when a small sample of a large population moves away to colonise a new area and becomes isolated; the allele frequencies of the founder population do not represent the genetic diversity of the larger original population
Selection pressures
the conditions or factors that influence allele
frequencies in a population by contributing to
the selection of which phenotypes survive in a given environment, e.g. availability of resources, environmental conditions, predators and disease
Natural selection
an evolutionary process whereby those individuals in a population that have a particular set of alleles are best suited to
the environment and will survive, reproduce and pass on their genetic information to the next generation
Selective advantage
a trait or phenotype that provides a survival advantage
Selective breeding or artificial selection
a process whereby humans intervene in the breeding of a species to keep desired features in a population that are economically beneficial or aesthetically pleasing, by selecting which organisms are to reproduce
Bacterial resistance
the ability of bacteria to survive and
reproduce in the presence of an antibiotic
that has been designed to slow their growth or
kill them; arises by mutation and becomes
widespread when antibiotics are over-used
Conjugation
the process by which genetic material is
exchanged between a donor bacterium and
a recipient bacterium; occurs through a tube via direct cell–cell contact; also known as horizontal gene transfer
Epidemic
the rapid spread of an infectious disease to a
large number of people within a population
Pandemic
an outbreak of infectious disease that occurs over a wide geographical area, affecting a
large number of people
Antigenic drift
mutations altering viral surface antigens,
making the virus unrecognisable to the host’s
immune system; can result in an epidemic
Antigenic shift
reassortment of genes on genomes from
different viruses infecting the same host cell, altering viral surface antigens, resulting in
novel strains that can cause pandemics
Fertile
able to reproduce
Viable
able to survive
Speciation
the evolutionary process of forming a new
species from a pre-existing ancestral species
Reproductive isolation
the inability of two groups of organisms to interbreed successfully; genetic isolation also ensures there is no gene flow between the
two populations
Allopatric speciation
a form of speciation that occurs when a
geographical barrier physically divides a population; the two subpopulations accumulate so many genetic differences that
they become reproductively isolated and are considered different species
Sympatric speciation
a form of speciation that occurs without
the involvement of a physical barrier; often
occurs in plants as a consequence of
polyploidy
Divergent evolution
where two or more species form from a single ancestral species over time
Adaptive radiation
the rapid diversification of a large number
of related species from a single ancestral
species
Plate tectonics
a scientific theory that focuses on the
separation of Earth’s crust into plates that
move across the underlying mantle
Geological time scale
a scale dividing Earth’s history into intervals
according to the geological and biological events and conditions present at that time
Biodiversity
the variety of plant and animal life in an
ecosystem at any given time
Period
a time interval characterised by specific rock
layers; periods are subdivisions of eras
Era
a subdivision of an eon
Eon
a long period of time that consists of at least two eras
Supereon
a period of geological time that consists of more than one eon
Cyanobacteria
a group of prokaryotic microorganisms
that are capable of photosynthesis;
recognised as the earliest form
of life on Earth
Stromatolite
a structure that consists of layered deposits
made by cyanobacterial colonies; fossilised
stromatolites are among the earliest fossils known
Invertebrate
an organism that
does not have a
backbone
Cambrian explosion
a rapid increase in complex biodiversity
within the fossil record that occurred at the
beginning of the Cambrian period
Arthropod
a type of animal that has no internal
backbone, a segmented body and a hard,
external covering known as an exoskeleton
Brachiopod
a marine animal with no internal backbone and a hinged upper and lower shell
Chordate
any animal that contains evidence of a spinal cord at some point in its development
Vertebrate
having a backbone
Myriapod
a subphylum of mostly terrestrial arthropods including milipedes, centipedes, and other ‘many-legged’ invertebrates
Tetrapod
any vertebrate animal that has four legs
or limb-like attachments, e.g. amphibians,
reptiles, birds and mammals
Amphibians
a class of tetrapods that are semiterrestrial,
with young living in water before moving to
land as adults; examples are frogs, toads and
salamanders
Reptiles
a class of air-breathing tetrapods with skin covered in scales, that lay eggs on land
Theropod
a type of carnivorous dinosaur with short forelimbs that ran on powerful, hind legs
Sauropod
a large herbivorous dinosaur characterised by its long neck and tail, and four-legged stance
Niche
the role that a species plays within its ecosystem
Hominoid
a superfamily consisting of all current and extinct humans and apes
Hominin
the subfamily consisting of all current and extinct bipedal primates
Megafauna
large or giant mammals that were still living in the Quarternary period
Background extinction rate
the normal extinction rate expected to occur over a period of time due to natural environmental factor
Fossil
the remains or traces of a preexisting life form
Fossil record
a record of organisms that once lived, through
geological time, as documented by fossils
Palaeontologist
a scientist who studies fossils
Trace fossil
fossilised signs or remains of an organism’s
activity, e.g. tracks
Petrification
the replacement of an organism’s organic matter with minerals, turning it into a stony material
Mould fossil
an impression that forms from the decay of the organism within a rock
Cast fossil
fossil formed when an organism decays, leaving an impression, which fills with minerals, resulting in a 3D object of the organism’s external surface
Sedimentary rock
a type of rock that is formed from the
accumulation of sediment into layers
Metamorphic rock
a type of rock that arises from the
transformation of existing rocks
Sediment
naturally occurring material that is formed through the effects of weathering and erosion
Transitional fossil
a hybrid fossil that shows traits of both an ancestral group and a descendant group
Absolute dating
determines the actual age of the specimen being analysed
Relative dating
determines the age of a specimen by
comparing its placement with that of other
fossils or the rock layers it is found in
Stratigraphy
a branch of geology that uses the ‘principle of
rock succession’ to examine the order and position of strata in connection with fossilised
remains
Index fossil
a fossil that is used to date and correlate
the strata within which it is found
Radiometric dating
absolute dating that uses the concept of
isotope decay to determine the age of a geological sample
Isotope
variant of an element that differs in the number of neutrons in the nucleus
Half-life
the time taken for 50% of a an unstable
parent isotope to decay into its corresponding
stable daughter isotope
Structural morphology
the study of an organism’s features and form
to determine the evolutionary relationship of
species
Homologous structure
a structure within a group of species that
performs a different function yet has the
same underlying structure
Divergent evolution
where two or more species form from a single ancestral species over time
Vestigial structure
a structure within an organism that is no longer functional but served a purpose in a common ancestor
Primate
the order consisting of all current
and extinct humans, apes and monkeys,
characterised by having dextrous hands with opposable thumbs and a relatively large and developed brain
Molecular homology
the analysis of DNA and amino acid sequences
as evidence of evolutionary relationships
Phylogeny
a branch of science that studies the evolutionary relationships between a group of species
Phylogenetic tree
a branching diagram used to represent the
evolutionary relationships between species
Taxonomy
the process of identifying, naming and
grouping organisms
Homologous structure
a structure within a group of species
that performs a different function yet has the same underlying structure
Molecular phylogeny
comparison of nucleotide sequences of
genes and amino acid sequences of proteins,
from which evolutionary relationships can
be inferred
Primate
the order consisting of all current
and extinct humans, apes and monkeys,
characterised by dextrous hands with opposable thumbs and a relatively large,
developed brain
Hominoid
the superfamily consisting of all current and
extinct humans and apes
Hominin
the subfamily consisting of all current and
extinct bipedal primates
Bipedal
able to walk on two legs or upright; bi = two, pedal = foot/feet
Genus
a group of related organisms that share a recent common ancestor
Species
a group of organisms that can interbreed,
producing fertile and viable offspring
Bipedalism
the characteristic of being bipedal,
i.e. walking upright on two legs
Foramen magnum
hole in the base of the skull through which the spinal cord enters/exits the skull
Molecular homology
the analysis of DNA and amino acid sequences
as evidence of evolutionary relationships
Molecular clock
using the predicted mutation rat e of
DNA (or amino acid) sequences to determine
the approximate time at which two species
diverged
Connection to Country
the relationship between people and their
indigenous land or environment
Interbreed
mate with an organism of another species
(sometimes used between different genetic groups or populations)
Putative
a term used to describe something that
is expected or assumed to have existed, without any current direct proof
