UNIT 5: DNA Structure and Mitosis Biology IDAYSHEET 47: DNA, Chromosome & Cell Division Review

Name: _______________________________ Date: _______________

Catalyst/Bellringer: Active Reading – Read the passage below using your reading strategies (underline, highlight and/or circle important information).

Double-Crossed! Rosalind Franklin never got proper credit for her revelation that the DNA molecule was a double helix.

Discrimination can be like the structure of an atom: Even if you can’t see it with the naked eye, you know it’s there.

What Rosalind Franklin faced in her scientific career might not have been overt (plain) sexism, but rather a subtle (delicate) refusal to take her seriously. Yet without her efforts, the two men who mapped the structure of DNA could not have made their discovery over 50 years ago.

As we begin to study the awesome structure of DNA, some people find it necessary to pause and remember the woman who did the groundwork for understanding DNA, yet received none of the public credit – and to ask if such a miscarriage of justice could happen again.

“It could,” say Brenda Maddox, whose biography, “Rosalind Franklin: The Dark Lady of DNA,” was published recently. “Women are making their way very slowly in the sciences.”

Few people outside of the scientific community have heard of Franklin, who died in 1958 at age 37. But it was her meticulous (careful) research that tipped off James Watson and Francis Crick that the DNA molecule was a double helix, and revealed its significance (importance) in the transfer of genetic information from cell to cell.

Watson and Crick were awarded the 1962 Nobel Prize for their discovery. Pivotal (critical) to the breakthrough, however, were the X-ray photographs of the DNA molecule made by the Franklin, a crystallographer who specialized in producing marvelously detailed images of microscopic structures, images that required hundreds of hours to develop. In 1953, as various groups were trying to nail down the structure and function of DNA, Franklin’s former lab partner, Maruice Wilkins, showed her photographs to Watson and Crick behind her back, setting the stage for the duo’s “Eureka!” moment. The crucial (important) image, called Photograph 51, distinctly (clearly) showed the twined strand that would constitute what is routinely acknowledged as the most significant scientific discovery in the second half of the 20th century.

As Watson recounts in “The Double Helix” (1968), his memoir about the race to unlock the secret of life, “The instant I saw the picture my mouth fell open and my pulse began to race.” In the same book, which became a best seller, Watson is dismissive of Franklin and her work, complaining about her clothes and her appearance.

“The best home for a feminist, “ he added, “is someone else’s lab.” Franklin died of ovarian cancer – doubtless brought on, in part, by exposure to radiation during many years of X-ray work Maddox observes – before the issue of her contribution could be addressed. Would it happen like that today?

“I want to say it would happen much less frequently,” say Londa Schiebinger, a professor of the history of science at The Pennsylvania State University and author of “Has Feminism Changed Science?” (1999). “But few inroads have been made. I don’t find the sense that this has all been taken care of.”

While the number of women in all branches of the sciences has been steadily increasing, a misogynistic (distrust of women) attitude persists (continues), says Geller, a senior scientist as the Smithsonian Astrophysical Observatory in Cambridge, Mass. “Women have much less access to the resources necessary to hold on to major research results, “ she says. “They do not have the administrative positions and receive fewer financial resources.”

“Their groups are smaller or non-existent,” adds Geller, who in 1975 was only the second women ever to earn a doctorate in physics at Princeton University. Often what they face, Geller and others report, is not overt, in-your-face prejudice but a discouraging “boys’ club” atmosphere such as that that prevailed at King’s College in London just after World War II, when Franklin, the bright young woman with a PhD in physical chemistry from Cambridge University, arrived and began work.

Detailing the Double Helix

Armed with Franklin’s Photograph 51, Watson and Crick were finally able to detail the double helix correctly. On February 28, 1953, Watson records in his memoir, Crick raced into a pub and told his friends the secret of life was a secret no more. “In the excitement of the discovery,” Maddox writes, “it seems to have escaped their notice that while Rosalind’s work was fundamental to their discovery, she had not been consulted on its use.”

Franklin died before Watson and Crick became household names on the back of her work. It was only in 1975, when Anne Sayre, a friend, published a biography of Franklin that the world at large became aware of her contribution.

Review Questions:

1. What was Rosalind Franklin’s contribution to our understanding of DNA’s shape?

2. What did James Watson and Francis Crick do to earn a Noble Prize?

3. Explain a time when you were double-crossed:

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Today’s Objectives: I CAN demonstrate my understanding of DNA shape, its ability to replicate, how it coils into chromosomes, and cellular division.

Homework 47 is due at the beginning of next class.

Activity 1: Review (Use Daysheets 44, 45 & 46 to help you answer the following questions)

1) If you were given the one strand of DNA below, what would the complementary strand’s bases be?

2) What is the picture of? _____________________________________

3) Who created this picture? __________________________________

A CGA TT AC

_________ ___ ___ ___ ___ ___ ___

4) What are the building blocks of DNA? __________________________

5) Label the picture of the DNA nucleotide below:

6) Use the provided word bank to label the following diagram:

Word Bank: Cell DNA Base Pairs Nucleus Chromosome

7) The figure below shows DNA replicating. In the space provided, describe what is occurring at each letter section of the figure.

A B

A

C A: _______________________________________________ _______________________________________________ _______________________________________________

B: _______________________________________________

8. Draw a chromosome and use the following words to correctly label your diagram:

Centromere Chromatid DNA Sister Chromatids

9. A segment of DNA that codes for a protein is a

a. protein b. gene c. chromatid d. deoxyribose

10. What is the process during which the nucleus of a cell is divided into two nuclei?

a. fertilization b. replication c. cytokinesis d. mitosis

11. The process during cell division in which the cytoplasm divides is called

a. prophase b. mitosis c. cytokinesis d. telophase

12. How many chromosomes will each daughter cell have when this cell completes mitosis? ________

13. List the four phases of mitosis and the memory clue for each phase below:

1. Phase: _________________________________ Memory Clue: _____________________________________2. Phase: _________________________________ Memory Clue: _____________________________________3. Phase: _________________________________ Memory Clue: _____________________________________4. Phase: _________________________________ Memory Clue: _____________________________________

Activity 2: One-Pager

Directions: Fill the entire page with information that you believe to be important for your quiz today. You must use at least 3 different colors when completing your One-Pager. You can use words, word art, pneumonic devices, memory clues, and pictures.

HW47: Enzymes Revisited Biology IName _________________________________

Date ___________1. Label the following picture of an enzyme using the following terms: Enzyme, Substrate,

Active Site

Use the following graph to answer questions 2-4.

2. Which of the chemical reactions (catalyzed of uncatalyzed) in the graph above will happen at a faster rate? _____________________________________

3. Which of the chemical reactions has a lower activation energy in the graph above, the catalyzed or the uncatalyzed reaction? ______________________________________

4. Which of the chemical reactions above (catalyzed or uncatalyzed) has an enzyme present? _________________________________

Use the following graph to answer questions 5-6.

5. Using the graph above, which of the following chemical reactions will proceed at a faster rate (with an enzyme or without an enzyme)? _________________________________________

6. Using the graph above, which chemical reaction will have a lower activation energy (with enzyme or without an enzyme)? ___________________________________

7. The molecule on which an enzyme acts is called the

a. substrate b. active site c. activation energy d. product

8. The site on which the substrate on the enzyme is called the

a. substrate b. active site c. activation energy d. product

Using the graph below, answer questions 9-11.

9. What is the optimal pH of Salivary amylase? _____________

10. What is the optimal pH of Pepsin? _____________

11. What is the optimal pH of Arginase? _____________

12. What is the molecule of energy for the body?

a. oxygen b. ATP c. glucose d. carbon dioxide

13. Green plants capture light energy in the process called

a. photosynthesis b. cellular respiration c. fermentation d. activation energy

14. All living things use a process called __________________________________________ to obtain energy from the bonds of food molecules.

a. photosynthesis b. cellular respiration c. fermentation d. activation energy

15. ____________ is responsible for speeding up chemical reactions by lowering activation energy.

a. carbohydrates b. lipids c. enzymes d. DNA