Toxins Flashcards
What are the functions of toxins?
Target specific cells in an organism, punching holes in their membranes, or modifying intracellular components
What is toxigenesis?
The ability to produce toxins
What are endotoxins?
Structural components of bacteria
Where are endotoxins located?
On the cell envelope, on the outside surface of bacteria
What are lipopolysaccharides?
Large molecules that are a vital component of the outer membrane of Gram-negative bacteria
What recognises forign molecules and alerts the immune system?
Patternn recognition receptors
What are exotoxins?
Usually proteins secreted by bacteria and stimulate host responses
Are toxins major contributors to disease?
Yes
What do enterotoxin, neurotoxin and hemolysin describe?
The targets of bacterial exotoxins
What are some common activities for exotoxins?
Degrading host membranes and forming pores in host membranes
What are the two subunits of toxins?
A and B
What is the subunit A?
Active
Has the toxic activity
What is the subunit B?
Binding
Binds to host cells
Does the A subunit act before subunit B?
Yes, the A part is delivered to the host cell through interactions between host cell and the B part
Where is AB toxin secreted from?
Bacterial cell
Where does B toxin bind to?
A specific receptor of host cell
Where is A toxin transferred?
Across host membrane into the host cell
What is A toxin able to do once in the host cell?
Interfere with normal cell function
What is diphtheria?
Thick coating at the back of the throat
What can diphtheria lead to?
Difficulty breathing
Paralysis
Death
What does diphtheria toxin cause?
A block of protein synthesis in the host
How much of diphtheria toxin is enough to kill a cell?
A single molecule
What is the mortality rate of diphtheria in the young?
High
Why is diphtheria morality in the young high?
The destruction of tissues in vital organs due to the blockage of protein synthesis
What does the AB diphtheria toxin bind to?
The Heparin-binding epidermal growth factor to gain entry into the host cell
What are enterotoxins?
Exotoxins that act on enterocytes
What do shiga and shiga-like toxind target?
Cells in the small intestine to shut down protwin synthesis
What is Cholera?
A waterborne infection with vibrio cholerae
What are the symptoms of cholera?
Massive fluid loss
Life threatning dehydration
What AB toxin affects several regulatory changes within cells?
Cholera toxin
What are botulinum and tetanus toxins produced by?
Clostridium botulinum and clostridium teteni
What is an endospore?
Forming soil bacteria
What do neurological toxins involve?
The secretion of AB exotoxins that function at neurotoxins
Where does C.botulinum grow?
Directly in the intestine or in contaminated preserved foods
How can C.botulinum be produced?
In the body or ingested if present in foods
What does botulinum toxin prevent when acting at the motor end plate?
Prevents acetylcholine release from vesicles
What toxin causes a lack of stimulus to the muscle fibres, irreversible relaxation of the musces and prevents contraction?
C.botulinum
What stops acetylcholine release at the junction?
Glycine released from inhibitory neurons
Where does C.tetani grow?
In deep puncture wounds
Why does tetanus toxin bind?
To prevent release of glycine from the inhibitory neuron
What causes constant excitation of the muscles, uncontrolled contraction and spastic paralysis?
Tetanus
