James Watson and Francis Crick
1930-1950 hope this helps
Hi,
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.
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Hope it help!
<u>ANSWER:</u>
The muscles and joints allow the hands to perform their function of holding and grasping a wide variety of things.
<u>EXPLANATION:</u>
- The structure of hands is "very delicate and complex". The tendons, nerve fibres, tissues and thin muscles are located right under the skin.
- The bones of the hand including the 4 carpal bones, 5 metacarpal and 14 finger bones are all connected by joints and ligaments and these allow the hand to grasp things.
- The wrist is made of "two parts of a joint" that allow the extension and stretching of hands.