Good Afternoon! Please get a computer, log on, and navigate to the “Links” section of the class website….

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

Finish for HW!

Characteristics of Living Things 1. Living things are made of cells 2. Living things reproduce 3. Living things are based on a universal genetic code (DNA) 4. Living things grow and develop 5. Living things obtain materials and energy 6. Living things respond to their environment 7. Living things maintain a stable internal environment 8. Living things, as a group, change over time.

1. What does DNA stand for? Deoxyribonucleic acid

2. Why is DNA referred to as “The blueprint of life?” Contains the instructions for building an organism; same molecule used by ALL living things.

3. Where in the cell is DNA found? In the nucleus

How does all that DNA fit into the nucleus? 1. Get gelatin capsule from teacher. 2. Cut a piece of thread 10 m long (from front wall to 2 nd lab table). This represents a single DNA molecule. 3. Try to put the “DNA” thread into the “nucleus” capsule.

How does all that DNA fit into the nucleus? Based on your results, how do you think a cell fits DNA into its nucleus? By twisting, wrapping, and compressing it into bundles called “chromosomes.”

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 chemical compounds that make up the “rungs” of the DNA ladder? Which of these nitrogen bases always pair with which? A = Adenine T = Thymine G = Guanine C = Cytosine A pairs with T G pairs with C

6. Why is the order in which the bases are arranged in the DNA molecule important? Order of bases is the code cells use to make different proteins.

Functions of proteins in living things: Build muscles, tissues, cells Help fight diseases (antibodies) Help digest food (enzymes) Help transport things in and out of cells

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

How big is 3 billion? Counting to one billion would take about 95 years (assuming it takes 3 seconds to say each number) 3,000,000,000 sec ÷ 60 sec/min ÷ 60 min/hr ÷ 24 hr/d ÷ 365 d/yr = 95 yrs Counting to 3 billion would take almost 300 years…..

8. What percent of all human DNA is identical? Using this percentage, how many base pairs would be the same? Show your work! 99.9% = 99.9/100 = ,000,000,000 x.999 = 2,997,000,000 pairs the same.

9. If you compared the DNA of two humans, and compared the DNA of two chimpanzees, whose DNA would be more similar: the two humans or the two chimpanzees? Why? The two humans. Humans are a younger species; less time for the DNA to mutate, change over time.

10. 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 processes the same, like cell respiration.

11. 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 across U.S. = 3,000 mi. 5,682,000,000 mi. ÷ 3,000 mi. = 1,894,000 cross country trips!

11. 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 = 238,855 miles 5,682,000,000 mi. ÷ 238,855 mi. = 11,900 trips to moon and back!

Questions?

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.

2012: Enzo Di Fabrizio, physics professor at the Magna Graecia University in Catanzaro, Italy, gets photo of DNA using an electron microscope.

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

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.