Harshey and Chase did a great experimentation which was basically a two step experiment to prove that DNA and not proteins are the actual carriers of genetic information from parents to offspring.

In the first part of their experiment, they used bacteriophages (virus that eat bacteria). They used radioactively labeled sulphur(35S) medium to grow bacteriophages and observed that all the bacteriophages had proteins with radioactive sulphur(35S).

In the next step they allowed these phages to infect bacteria and to their surprise, they found that the bacteria did not had radioactively labeled sulphur in them because the coat of bacteriophage stays outside the body of bacteria when it attacks it. This proved that DNA not proteins were the hereditary material.

To make their results more reliable, they did a second experimentation in which, they marked the DNA of the phage with radioactive phosphorus 32P. After labeling DNA, they repeated the same experiment and this time, they found radioactive phosphorus inside the bacteria.

<em>This meant that the bacteria had DNA of phage entered inside them and this again proved that DNA not proteins are the hereditary material. You can see attached image for better understanding. </em>

Hope it help!

7 0

3 years ago

Q.#23.Lymph nodes are soft, small, round- or bean-shaped structures. They usually cannot be seen

rodikova [14]

Answer:

Lymph nodes swell to protect us from illness if they do not swell non fatal illnesses could spell out death

Explanation:

5 0

3 years ago

What major factors affected earth's changing climates?

Flura [38]

I just had this answer but it hasn't been graded. I put 1. Meteor impacts, 2. volcanic gases and 5. Milankovitch cycles. I didn't put earthquakes because I wouldn't think it would affect the climate changing since they just affect ground movement.

8 0

4 years ago

Read 2 more answers

Which is an example of positive gravitropism?

AveGali [126]

Answer:

c. the plant root growing down into the soil

Explanation:

The plant root going down deep into the soil is an example of positive gravitropism. Gravity pulls everything towards the center of earth i.e. downwards and roots follow the direction of gravity automatically by growing downward towards soil that is why it is known as positive gravitropism. In short we can say that root favors the direction of gravity.

Shoot on the other hand show negative geotropism/gravitropism i.e. it grows towards the opposite direction of gravity. Shoot grow towards upside direction i.e. away from the surface towards sky.

4 0

3 years ago