It is a wels catfish also called sheatfish it also looks like a catfish
The major contribution made by Avery, MacLeod, and McCarty was 'transformation of nonvirulent cells with a DNA extract was blocked only if DNase was added'. This observation supported the idea that the transforming agent in Griffith's experiment was DNA.
The Avery–MacLeod–McCarty experiment showed that DNA was the transforming agent observed in Griffith's experiment.
Griffith's experiment (1928) suggested that bacteria were capable of transferring genetic information (DNA) by a process of horizontal gene transfer called transformation.
While the bacteria were killed by heat, Frederick Griffith observed that the DNA had was taken up by II-R strain bacteria via transformation.
Avery–MacLeod–McCarty experiment observed that protease enzymes did not destroy the transforming agent (but DNAse destroyed this transforming principle), thereby suggesting that the transforming agent in Griffith's experiment was bacterial DNA.
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Answer:
The correct answer is "the S layer may play a role in protecting cells from viruses and predatory bacteria found in nature but not in laboratory cultures".
Explanation:
The S-layer (surface layer) is a part of the cell's envelope comprised of of identical proteins or glycoproteins that could be found in archaes and some bacterias in nature. The function of the S-layer is unknown, however the fact that is only seen in nature suggest that it may play a role in protecting cells from viruses and predatory bacteria found in nature but not in laboratory cultures. It is likely that archaes and bacteria synthesize the S-layer when they recognize viruses and predatory bacteria in nature, the S-layer is not synthesized in laboratory cultures because these pathogens are not present.