7A - Detecting Pathogens Flashcards
antigen
any molecule that may
trigger an immune response
pathogen
an agent that causes
disease
non-self antigen
a molecule from
outside the body that is recognised by the immune system and
initiates an immune response.
Also known as a foreign antigen
(MHC) markers stands for
major histocompatibility complex
MHC Class I markers
are expressed on all nucleated cells in the body.
virtually all cells in the human body except for those without a nucleus (e.g. red blood
cells) express MHC Class I markers.
MHC Class II markers
are found on specialised cells of the immune system.
autoimmune disease a disease
in which an individual’s immune system initiates an immune response against their own cells
allergen
a non-pathogenic antigen
that triggers an allergic reaction- an overreaction
of the immune system to a nonpathogenic antigen
cellular pathogen
a pathogen that
has a cellular structure and exhibits the processes of a living organism.
Examples include bacteria, fungi,
protozoa, and parasites
non-cellular pathogen
a pathogen
that neither has a cellular structure nor exhibits the processes of a living organism. Examples include viruses and prions
bacteria description
Unicellular prokaryotes that can infect almost
any part of the body.
- can cause disease
through the production of toxins and enzymes
which either affect the functioning of cells or cause their death.
bacteria reproduce via
Bacteria typically reproduce
asexually via binary fission.
fungi descp
Eukaryotic organisms that include yeasts and
moulds and contain long, branching filaments
called hyphae.
fungi reproduce via
Fungi reproduce both through aesexual reproduction and sexual
reproduction via spore formation.
worms descp
Multicellular invertebrate parasites whose
development include egg, larval, and adult stages.
Can vary in length, with the longest worms being
over 55 m in length.
worms reproduce via
Worms reproduce sexually via a complex life cycle.
protozoa descp
Single-celled eukaryotes that can be free-living
or parasitic.
- have many different
mechanisms of action –
some can inhibit nucleic acid synthesis, protein synthesis, and various stages of cellular respiration.
protozoa reproduce via
asexual reproduction and sexual reproduction.
cellular pathogens are
bacteria, fungi, worms and protozoa
non-cellular pathogens are
viruses and prions
virus descp
An infectious agent composed of genetic material (DNA or RNA) inside a protein coat (capsid) - sometimes has lipid envelope.
how do viruses cause diseases
through the lysis of cells
during viral replication
- formation of cancer by
affecting gene expression
- over-stimulation
of the immune system leading to organ damage.
virus reproduce via
not able to
independently reproduce.
they insert their genetic material into a host’s cell and use the cell’s
machinery to replicate.
prions descp
Abnormally folded proteins
- can induce normal proteins nearby to become
misfolded.
- only occur in mammals and affect only the brain and other neural structures.
- only known infectious agents that don’t contain nucleic acids.
prions reproduce via
Prions do not reproduce in the normal sense of the word - instead,
they induce misfolding in nearby proteins, thereby ‘spreading’
throughout a tissue.
