Answer:
In 1928, Fred Griffith performed an experiment revealing that genetic material can be passed between two different stains of the bacteria.
Explanation:
In 1928, Frederick Griffith, a British bacteriologist conducted some experiments to develop a pneumonia vaccine. He used mice and two strains of Streptococcus pneumoniae bacteria, known as R and S in his experiments.
The live R strain bacteria had a rough appearance and were nonvirulent. When he injected R bacteria into mice, they did not cause pneumonia. The live S strain bacteria had a smooth appearance due to their polysaccharide coating and were virulent. When injected into mice, the mice died as a result of pneumonia. The polysaccharide coating protected the S bacteria from the immune system of the mice.
Griffith then injected mice with heat-killed S bacteria (the heat killed the bacterial cells) and they did not cause pneumonia in mice. But when he injected a combination of non-lethal R bacteria and non-lethal heat-killed S bacteria into mice, the mice died from pneumonia. When he examined the blood sample from the dead mice, he found that the blood sample contained live S bacteria. This finding leads him to the conclusion that the nonvirulent R-strain bacteria had been "transformed" into virulent and lethal S-strain bacteria by taking up a "transforming principle" from the heat-killed S bacteria.
This experiment was then used for additional experiments conducted by Avery, McCarty, McLeod and then by Hershey and Chase. They found the evidence that the transforming principle from Griffith's experiment was actually the hereditary material, DNA. The DNA of the S strain bacteria had survived the heating process. This DNA that contains the genes for the production of the protective polysaccharide coating was taken up by the R strain bacteria. The transformed R strain bacteria were now protected from their host's immune system and this process of transferring genetic information between different bacterial strains is known as transformation.
I’m pretty sure it’s because the introns are removed and the Exon’s are kept and joined together to leave the cell. This happens during splicing..
Answer:
Compound: These are made of the various type of same or different elements. These elements show a specific ratio in a particular compound.
The physical properties are traits of a particular compound or element that can be observed physically like the state of matter, color, odor, and other. The chemical properties and physical properties of compounds and elements they formed are different.
It is not comparable as the elements have no or very little individual value in a compound. For instance, water made of hydrogen and oxygen, where water is liquid and constituents are gas.
