How do scientists disagree on the number of biomes that exist?

Lister cultured the bacteria responsible for milk spoilage. True False

Ann [662]

Answer:

True

Explanation:

8 0

3 years ago

alfred hershey and martha chase designed an experiment to determine the chemical makeup of griffith's transforming principle. de

MAXImum [283]

Answer:

Bacteriophages (phages) are viruses that infect only bacteria and do not infect mammalian or plant cells. Phages are ubiquitous in the environment. Phages or bacteriophages were chosen as a model system for their simplicity, as they only contained protein-coated nucleic acid. Alfred D. Hershey and Martha Chase (who were part of the bacteriophage group) in 1952 studying the infection of the bacterium Escherichia coli by the T2 phage show that the information definitely resides in the DNA. They used phage with either [32P] -labeled DNA or [35S] -labeled proteins to infect the bacteria. Immediately afterwards, they centrifuged the sample so that the infected bacteria remain in the pellet and the virus capsids (proteins) remain in the supernatant. [35S] is found in the supernatant, whereas [32P] is found in bacteria. After one cycle of infection, it was observed that when phage labeled in the [35S] proteins were used, only 1% of the radioactivity was incorporated into the progeny. But when phages were [32P] labeled, more than 30% of the radioactivity was in the progeny. They showed directly that what is transmitted from one progeny to another is the DNA and not the proteins, despite having first "diluted" in a bacterium.

Explanation:

Bacteriophages are viruses that infect bacteria in a specific way. Bacteriophages, like other known viruses, are found in an intermediate zone between living organisms and inert matter. Bacteriophages bind to the host pathogenic bacterium, introduce their genetic material, replicate inside it and destroy it. Hersey, along with his assistant Martha Chase, used phages because they knew that T2 phages were made up of 50% proteins and 50% nucleic acids and that phages entered bacteria and reproduced. As the progeny carried the same infection traits, the genetic material of this had to be transmitted to the offspring, but the mechanism was unknown. These scientists carried out an experimental work with the T2 virus, a bacteriophage that infects the bacterium Escherichia coli, which it reproduces by attaching itself to the outer wall of the bacterium, injecting its DNA into it where it replicates and directs the synthesis of the phage's own proteins. Phage DNA is encapsulated within proteins and produces phages, which lyse or disrupt the cell and release phage from progeny. They infected a culture of bacteria with radioactively labeled phages: the protein coat with sulfur (35S) and its DNA with phosphorus (32P). After infection, they separated the phages from the bacteria by violent shaking using a mixer (hence the name of the experiment). By centrifugation the much smaller phages remained in the supernatant and the much larger bacteria in the pellet. 85% of the radioactivity corresponding to DNA appeared in the pellet and 82% of the protein in the supernatant. This result supported the idea that DNA was the only component of the bacteriophage that penetrated the interior of the bacteria and, having the ability to form new phages, constituted the genetic material.

5 0

3 years ago

Barnacles attach to shellfish for transportation. The shellfish is not helped or harmed. This is an example of_

Vesna [10]

The correct answer is:

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→ " commensalism" .

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Note: "Commensalism" refers to a symbiotic relationship {"symbiosis"} between two (2) organisms — in which one organism benefits and the other organism is neither helped nor harmed.

{ i.e. " +, 0 " ; that is: "plus" sign for "one organism benefits" ;

"zero" sign for "neutral" ;

(in that the other organism is neither helped nor harmed.}.

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In the example given in the question, the two (2) organisms are:

1) the barnacles; and: 2) the shellfish.

The barnacles benefits by given a place to attach for the purpose of transportation (by using the shellfish to "cling to"}.

The shellfish are neither helped (benefitted in anyways from the attachment from the barnacles— nor are the shellfish harmed in any way.

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Hope this answer helps you!

Best wishes in you academic pursuits

— and within the "Brainly" community!

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8 0

3 years ago

How might giving a mumps vaccine to a boy protect his reproductive health later?

ArbitrLikvidat [17]

There are a small number of boys who, after possibly contracting mumps, could experienced decreased fertility in the future. Giving a mumps vaccine, since it's a weaker version of the virus, will allow the body to fight it off without the negative effects that could come with a full version of the illness.

4 0

3 years ago

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PLEASE HELP AND ANSWER AS MANY AS YOU CAN THIS IS MY FINAL EXAM

Fantom [35]

Answer:

2. Direct, 3. 1 2 and 3 I couldn't find 1 srry. :)

Explanation:

4 0

3 years ago

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