Select characteristics exhibited by endotoxins, but not exhibited by exotoxins. Check All That Apply 8 00:54:26 eBook Composed of lipopolysaccharide Require very small doses to cause toxic effects Secreted from a living cell Heat-stable Have very specific targets Fever-inducing
The Correct Answer and Explanation is:
The correct characteristics exhibited by endotoxins, but not exotoxins, are:
- Composed of lipopolysaccharide
- Heat-stable
- Fever-inducing
Explanation:
Endotoxins and exotoxins are both types of toxins produced by bacteria, but they differ significantly in their chemical structure, how they act, and the symptoms they induce.
- Composed of lipopolysaccharide:
Endotoxins are part of the outer membrane of Gram-negative bacteria. They consist of a lipopolysaccharide (LPS) structure, which is a complex molecule made up of a lipid portion (lipid A) and a polysaccharide portion. In contrast, exotoxins are usually proteins and do not contain lipopolysaccharide. - Heat-stable:
Endotoxins are relatively heat-stable, meaning they remain toxic even after exposure to heat, often surviving temperatures of up to 250°C for 30 minutes. This is in contrast to exotoxins, which are generally heat-labile and lose their toxicity at high temperatures. - Fever-inducing:
One of the hallmark effects of endotoxins is their ability to induce fever. This is because endotoxins stimulate the body’s immune response, leading to the production of pyrogens that raise the body’s temperature. Exotoxins, on the other hand, do not typically induce fever.
Characteristics not exhibited by endotoxins:
- Require very small doses to cause toxic effects:
This characteristic is more common to exotoxins. Exotoxins can be extremely potent, with very small amounts required to cause damage, while endotoxins generally need higher quantities to elicit a toxic response. - Secreted from a living cell:
Exotoxins are actively secreted by living bacteria, whereas endotoxins are released when the bacterial cell dies and the outer membrane is broken down. - Have very specific targets:
Exotoxins tend to have very specific targets, affecting certain cells or tissues in the body. Endotoxins, however, have a broader effect, primarily inducing an immune response throughout the body rather than targeting specific tissues.
Thus, endotoxins have distinct features that set them apart from exotoxins in terms of structure, heat stability, and effects on the host.
