Chapter 10 : The Immune System & Mechanisms of defense
Pathogens cause disease
Living: Bacteria (prokaryotic), Fungi, Parasits - Nonliving organisms : Viruses, Prions
BACTERIA : single-celled living organism
Bacteria : Single-celled organisms with NO nucleus (prokaryotic) and NO organelles. Ribosomes are smaller than ours
& float freely in the cytoplasm. The outer wall is rigid & gives it shape (spheres, spirals…). All DNA in just one
chromosome (continuous loop anchored to plasma membrane)
Advantage ? small size = high surface-to-volume ratio.
Use ATP & amino acids,store carbohydrates and fats (like human cells). To get raw materials, break down raw
sewage (cause decomposition of dead animals & plants) or from soil and air.
VIRUSES : Tiny infectious agents
Viruses :Extremely small infectious agents with very simple structure : piece of RNA or DNA, in protein coat.
If they enter a living cell, use the cell’s organelles to make more virusses ! How do they enter a living cell?
ENDOCYTOSIS : inside, protein coats dissolve => viral genetic material incorporated in cell’s genetic material
MERGE their outer coat with cell’s membrane => release genetic material in cell’s cytoplasm
ATTACH to cell’s surface => inject their genetic material into the cell
Cell produces 1000s of copies of the virus instead of own metabolic activities => Possible effects :
Newly formed viruses can be released from cell membrane while cell is still alive
Cell can becomes so packed with viruses that dies, releasing a huge nr of viruses
PRIONS : Infectious proteins
Prions : misfolded form of normal brain cell protein that can trigger misfolding of nearby normal proteins (once
entered a nerve cell, misfolding process is SELF-PROPAGATING) => Infected brain cells die/burst, releasing prions to
infect other brain cells => Neurological symptoms and progressive degeneration.
Resistant to cooking, freezing, drying. No known cure. mammalian meat and bone meal products as cattle feed
have been banned ! (Mad cow disease, Creutzfeld-Jakob disease (CJD) – Dokter Prusiner)
THANSMISSIBILITY // MODE OF TRANSMISSION //VIRULENCE (how damaging?)=> determine health risk
Pathogens cause disease
Living: Bacteria (prokaryotic), Fungi, Parasits - Nonliving organisms : Viruses, Prions
BACTERIA : single-celled living organism
Bacteria : Single-celled organisms with NO nucleus (prokaryotic) and NO organelles. Ribosomes are smaller than ours
& float freely in the cytoplasm. The outer wall is rigid & gives it shape (spheres, spirals…). All DNA in just one
chromosome (continuous loop anchored to plasma membrane)
Advantage ? small size = high surface-to-volume ratio.
Use ATP & amino acids,store carbohydrates and fats (like human cells). To get raw materials, break down raw
sewage (cause decomposition of dead animals & plants) or from soil and air.
VIRUSES : Tiny infectious agents
Viruses :Extremely small infectious agents with very simple structure : piece of RNA or DNA, in protein coat.
If they enter a living cell, use the cell’s organelles to make more virusses ! How do they enter a living cell?
ENDOCYTOSIS : inside, protein coats dissolve => viral genetic material incorporated in cell’s genetic material
MERGE their outer coat with cell’s membrane => release genetic material in cell’s cytoplasm
ATTACH to cell’s surface => inject their genetic material into the cell
Cell produces 1000s of copies of the virus instead of own metabolic activities => Possible effects :
Newly formed viruses can be released from cell membrane while cell is still alive
Cell can becomes so packed with viruses that dies, releasing a huge nr of viruses
PRIONS : Infectious proteins
Prions : misfolded form of normal brain cell protein that can trigger misfolding of nearby normal proteins (once
entered a nerve cell, misfolding process is SELF-PROPAGATING) => Infected brain cells die/burst, releasing prions to
infect other brain cells => Neurological symptoms and progressive degeneration.
Resistant to cooking, freezing, drying. No known cure. mammalian meat and bone meal products as cattle feed
have been banned ! (Mad cow disease, Creutzfeld-Jakob disease (CJD) – Dokter Prusiner)
THANSMISSIBILITY // MODE OF TRANSMISSION //VIRULENCE (how damaging?)=> determine health risk
