The Secret of Photo 51 Video & DNA Model

PART ONE DIRECTIONS:

1)Read the following passage to yourself:

TheSecret of Photo 51 is a documentary video created by PBS Nova that highlights the life of Rosalind Franklin and her work with DNA. In the 1950’s, the race was on. At this time in history, science was unsure how DNA was constructed. Three groups of scientists were trying to unravel the molecular structure of DNA. Rosalind Franklin was the leader of one of those groups.

2)Go to Mr. Kobe’s website and watch Part 1 of the video.

PART TWO DIRECTIONS:

1)Read the following passage yourself:

Deoxyribonucleic acid (DNA) is a large molecule made from smaller units called nucleotides. From the picture to the right, you can see that every nucleotide is made from three smaller parts: (1) phosphate molecule, (2) sugar molecule, (3) nitrogen base. When combined, these three parts make a single nucleotide.

When nucleotides are combined, they create a larger molecule called a nucleic acid. DNA is one type of nucleic acid. You can see a nucleic acid to the left made from 8 nucleotides. Thispicture is very simplistic because in real life it is common for DNA to be made from millions of nucleotides bonded together, instead of only 8 nucleotides.

2)Go to Mr. Kobe’s website and watch Part 2 of the video

PART THREE DIRECTIONS:

1)Read the following passage yourself:

Prior to the 1950’s, scientists were unsure whether DNA was a double helix or a triple helix. This is because the technology in the 1950’s was not as advanced as it is today and it made obtaining pictures of DNA very difficult. Using the process of X-ray diffraction, Rosalind Franklin (working at King’s College in London) was producing the best images of DNA during this race to discover DNA’s structure.

2)Go to Mr. Kobe’s website and watch Part 3 of the video

PART FOUR DIRECTIONS:

1)Read the following passage yourself:

DNA has four nitrogen bases that seem to repeat over and over and over. The four nitrogen bases are called adenine (A), thymine (T), cytosine (C), and guanine (G). During the 1950’s, scientists were not sure if the nitrogen bases were arranged on the inside of the DNA molecule or on the outside.

Prior to the DNA race, a scientist named Erwin Chargaff (pictured above) made an important observation when studying DNA. Chargaff noticed that the amount of the nitrogen base “adenine” was always equal to the amount of the nitrogen base called “thymine.” He also discovered that the amount of the nitrogen base “guanine” was equal to the amount of the nitrogen base “cytosine.” For a while, no one knew why this was.

2)Go to Mr. Kobe’s website and watch Part 4 of the video

PART FIVE DIRECTIONS:

1)Read the following passage yourself:

The structure of DNA was finally solved by James Watson and Francis Crick. As mentioned before, Rosalind Franklin (King’s College London) was producing the best images of DNA with the help of X-ray diffraction. Without Franklin’s knowledge, her co-worker Maurice Wilkinsshowed some of her photographs to James Watson, who worked at rival Cambridge University. Together, Watson and Crick usedinformation from her photographsto calculate the molecular structure of DNA as a double helix.

Erwin Chargaff’s observations now made sense. The reason the amount of adenine (A) was equal to thymine (T) was simple. Adenine and thymine were bonded together! If there was a “T” on the left side of the DNA molecule, then an “A” would be on the right side. The same was true of guanine (G) and cytosine (C).

2)Using your combined strip 1 and strip 2….

  1. glue a rectangular shaped “ADENINE” onto the corner of the first sugar. The “Adenine” should be sticking out to the right of the sugar molecule. If you are confused, I have provided an example to examine.
  2. glue a rectangular shaped “GUANINE” onto the corner of the second sugar.
  3. glue a rectangular shaped “ADENINE” onto the corner of the third sugar.
  4. glue a rectangular shaped “THYMINE” onto the corner of the fourth sugar.
  5. glue a rectangular shaped “THYMINE” onto the corner of the fifth sugar.
  6. glue a rectangular shaped “CYTOSINE” onto the corner of the sixth sugar.

3)Go to Mr. Kobe’s website and watch Part 5 of the video.

PART SIX DIRECTIONS:

1)Read The following passage yourself:

On the day of their discovery on February 28, 1953, Watson and Crick walked into the Eagle Pub, which was located across the street from their Cambridge University laboratory, and interrupted the other customers who were eating lunch. In that pub, they proclaimed “We discovered the secret of life!” Shortly after that, their research paper was printed in the journal Nature.

2)Using your combined strip 3 and strip 4…

  1. Glue one blank rectangle onto the X of all six sugars. Once glued, the blank boxes should be sticking out to the left of the sugar molecules. If you are confused, I have provided an example to examine.

3)Go to Mr. Kobe’s website and watch Part 6 of the video.

PART SEVEN DIRECTIONS:

1)Read the following passage yourself:

In 1962, James Watson, Francis Crick, and Maurice Wilkins were awarded the Nobel Prize in Medicine. Sadly, Rosalind Franklin had passed away in 1958 due to ovarian cancer, which many believed she obtained during to her experiments with X-Ray technology as she took photos of DNA and other molecules. Had she survived, she likely would have been awarded the Nobel Prize as well since her work helped Watson and Crick uncover the mystery of DNA.

2)Go to Mr. Kobe’s website and watch Part 7 of the video.

3)Line up the nitrogen bases of strip 1 and 2, to the nitrogen bases of strip 3 and 4.

4)Glue the nitrogen bases together. This should create one large molecule of DNA, a double helix.

5)Follow Chargaff’s rules and handwrite the missing nitrogen bases into the blank nitrogen bases.