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likoan [24]
3 years ago
15

In the 1920s, bacteriologist Fred Griffith demonstrated that a heat-killed, infectious pneumococcus produced a substance that co

uld convert a harmless form of the bacterium into a lethal one. Fifteen years later, researchers prepared an extract from the disease-causing S-strain pneumococci and showed that this material could transform the harmless R-strain cells into the infectious S-strain form. This change to the bacteria was both permanent and heritable, suggesting that this "transforming principle" represents the elusive genetic material of the cells. But what kind of molecule was it?The researchers subjected their extract to a variety of tests to determine the chemical identity of the "transforming principle." In one experiment, they treated the material with enzymes that destroy all proteins. This treatment did not affect the ability of the extract to transform harmless bacteria into an infectious form.From this result, the researchers can conclude that:
Biology
1 answer:
Juliette [100K]3 years ago
5 0

Answer:

Some substance in the infectious S strain could change the harmless R strain into the more lethal form.

Explanation:

These first type of experiments where crucial to advance in DNA knowledge.

In one experiment, they treated the material with enzymes that destroy all proteins. This is important because scientist notice that there was something else that was causing the strain to change into a lethal form and was heritable (DNA).  Know a days we know that plasmids are responsible for such transformation.

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Help please !! I really don’t understand this much☹️
morpeh [17]
Ok, so I wrote these out just to make it a little bit easier for you to understand what I am about to explain.

So for the first one you have two different traits that can be inherited- having freckles or having no freckles, F and f respectively. The dominant trait (or having freckles) is shown by the capital F, and is almost always expressed over the recessive trait, or the lowercase f. So, for example, if you have a genotype of Ff, the trait having freckles will show up instead of not having freckles. The only way that you could have the trait of no freckles show up is if there are two recessive alleles for having no freckles, or ff. In this case, you have two parents who are both heterozygous for the trait of having freckles, so in other words the mother has Ff and the father has Ff. Each parent passes down one allele to the offspring, so since you are breeding Ff and Ff, you should result in having the possible genotypes of FF, Ff, Ff, and ff. This means that there is a 25% chance that the offspring will be homozygous for having freckles, a 50% chance that the offspring will be heterozygous for having freckles and a 25% chance that they would be homozygous for having no freckles, or a 1:2:1 ratio.

Incomplete dominance is a little bit different that just a normal monohybrid cross. Instead of just the dominant gene showing up in a heterozygous genotype, both traits show up. So like the question says, if a homozygous red flower plant was crossed with a homozygous white flower plant, their offspring would not just be white or red, they would be pink because it is a mixture of white and red. So then if you crossed the heterozygous, or Rr plants, the result would be a 25% chance of getting a homozygous RR red plant, a 50% chance of getting a pink Rr plant, and a 25% chance of getting a white rr plant, or another 1:2:1 ratio.

Sorry for the wordy answer, but hopefully this helps you understand this a little better :)

4 0
3 years ago
Increased production of goods makes our lives more comfortable, but causes an increase in the demand for energy and other resour
vladimir1956 [14]

Answer:

pollution levels in the atmosphere

Explanation:

One negative impact of increased production of goods is the increased levels of pollution in the atmosphere.

Pollution is the introduction of harmful substances into the environment beyond levels that are safe for life. The materials are the pollutants.

Production of goods or manufacturing generates a lot of waste with it. Air pollution is easily attributable to manufacturing.

Green house gases from combustion of fossil fuels to drive industrial processes generally leads to climate change.

Smokes and dusts can be produced by industrial processes and when scattered about causes pollution

3 0
3 years ago
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which system works together to provide protection for the body with the system shown in the diagram above? ​
olasank [31]
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7 0
3 years ago
What percent of marine creatures live in coastal waters?
astraxan [27]
Coastal waters have about 26% of all biological diversity. This world of seabirds, clams, crabs, starfish, anemones, fish, kelp, and marine mammals, among many others, is a beautiful place with many different types of plants and animal communities.
7 0
3 years ago
Can our cells carry out cellular respiration without oxygen? If so, how?
IRINA_888 [86]
Yes but just look it up also can someone answer my question? 10 points
4 0
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