Answer:
Alzheimer's disease is not an inevitable part of aging. Occasional forgetfulness is a normal part of aging, but AD is a serious condition that can cause significant cognitive decline. Symptoms usually start off mild and worsen over time as the disease progresses.
Explanation:
Answer:
The correct answer is D.
Explanation:
Bordetella pertussis is a gram-negative coccobacillus that causes a disease called whooping cough.
The bacterium infests the patients by colonizing lung epithelial cells. To do so, it requires adhesins, called filamentous haemagglutinin, fimbriae and pertactin. Once the bacterium is attached to the lung epithelial cells, it produces a cytotoxin that prevents their cilia from moving.
Another virulent factor from B. pertussis is the pertussis toxin, which alters host immune system through the inhibition of phagocytes response to it.
Answer:
Only the extracts from heat-killed cells treated with RNase are unable to transform nonvirulent bacteria into virulent bacteria.
Explanation:
The experiment by Avery, McCarty and MacLeod aimed to identify Griffith's "transforming principle," which is a principle that explains how transformation is a way of recombining, exchanging, or transferring genetic information between organisms or from one organism to another. For this, they used cell that were heat inactivated and purified the transforming principle of these cells.
The purified cells did not give positive results in the tests done by the scientists, but they presented transformants very similar to the DNA. However, Avery suspected that the result should be reinterpreted and that the molecule was not a DNA. This is because RNA degrading enzymes had no effect on the transforming principle and only RNase-treated heat-killed cell extracts are unable to transform non-virulent bacteria into virulent bacteria.
