ESSENTIAL QUESTION: HOW DO OUR CELLS DETERMINE WHO WE ARE? DNA Notes

1. Why is DNA referred to as a universal genetic code? It’s the same molecule used in all living things to carry genetic information

2. What does DNA stand for? Deoxyribonucleic acid “dee-ahk-see-righ-boh- noo-klay-ik-assid”

3. Why is DNA important to learn about? What determines what we look like and much of who we are. Helps us understand how all life on Earth works Shows us how characteristics/traits are passed on from parents to offspring Helps us learn what causes some diseases and how to cure them.

4. Describe the shape of a DNA molecule and draw a picture of a section of the molecule. “double helix” Twisted ladder

5. What are the four nucleotide bases that make up the “rungs” of the DNA ladder? Which bases always pair with which? A = Adenine T = Thymine G = Guanine C = Cytosine A pairs with T G pairs with C

6. How many base pairs are there in a complete set of DNA? 3 billion, or 3,000,000,000

7. What percent of all human DNA is identical? Using this percentage, how many pairs would be different? Show your work! 99.9% 3,000,000,000 x.999 = 2,997,000,000 3,000,000,000 – 2,997,000,000 = 3,000,000 pairs different

8. What percent of chimpanzee DNA is identical to human DNA? Using this percentage, how many base pairs are the same letters in the same order? Show your work! 98% 3,000,000,000 x.98 = 2,940,000,000 the same letters in the same order.

9. What percent of a banana’s DNA is identical to a human’s? How many base pairs would be the same letters in the same order? What similarities do we have with bananas that would explain this? 50% 3,000,000,000 x.5 = 1,500,000,000 the same letters in the same order. Many cell organelles are the same (nucleus, cell membrane, mitochondria, etc.) Many of the processes for making cell parts, for cell respiration, cell division the same.

10. If all the uncoiled DNA in one cell were three feet long, how many miles would the uncoiled DNA from all your cells stretch? Assume there are about 10 trillion cells in the human body (other estimates are as high as 100 trillion) and 1 mile = 5,280 ft. Show your work! 10,000,000,000,000 cells x 3 ft./cell = 30,000,000,000,000 ft. 30,000,000,000,000 ft. x 1 mi./5,280 ft. = 5,681,818,182 mi. Distance to moon and back = 240,000 mi. x 2 = 480,000 mi. 5,682,000,000 mi. x 1 trip/480,000 mi. = 11,800 trips to moon and back!

Where in the cell is DNA found? In the nucleus

How does all that DNA fit into the nucleus? 1. Remove the gelatin capsule from the envelope 2. Remove the 10 m of thread from the envelope and stretch it out to its full length. It represents a single DNA molecule. 3. Try to find a method to reconstruct the nucleus by inserting the “DNA molecule” into the capsule.

How does all that DNA fit into the nucleus? 1. Based on your results, infer how do you think a cell fits DNA into its nucleus? 2. What benefits does a cell receive by being able to put a large amount of genetic information in a small package? 3. How does this pose problems for a cell during DNA replication?

History of DNA: Gregor Mendel 1866 Czech monk who did experiments with pea plants to see how genetic traits were passed from generation to generation.

History of DNA: Friedrich Miescher 1868 Swiss physician who identified nucleic acid in nuclei of cells

History of DNA: Rosalind Franklin 1953 British biophysicist who took photo of DNA molecule using x-ray diffraction

History of DNA: Watson and Crick 1953 American and British scientists used Franklin’s photo and ball and stick models to infer double helix shape of DNA molecule.

What are genes and how are they important? Genes are segments of the DNA that carry genetic information. They code for proteins that carry out the function of the cell and gives us our physical, biological characteristics.

Every time you make new cells, the DNA has to be copied so the new cell has a complete set of genetic information…..