1. DNA

2. A. DNA
Living organisms are made up of cells that contain a substance called deoxyribonucleic acid (DNA).
DNA provides the instructions for building parts of the cell.
DNA is wrapped together to form structures called chromosomes that are found in the cell’s nucleus.

3. Chromosomes Made of DNA and proteins.
Humans have 23 pairs of chromosomes
One pair of 23 from the mother and 23 from the father.

4. A gene is a segment (part) of a DNA molecule that
contains information for making a protein.

5. 4. DNA contains four chemicals that are strung in patterns on extremely thin, coiled strands in the cell
Adenine, A
Thymine, T
Cytosine, C
Guanine, G.
5. Each cell in your body contains about 6 feet of DNA thread, for a total of about 3 billion miles (if all your DNA threads were stretched out straight) of DNA inside you!

6. The stringy stuff in the test tube is DNA that has been extracted from an organism. But you can’t tell which one of these organisms it came from just by looking at it. That’s because DNA looks exactly the same in every organism on Earth.

7. Every cell in our body contains a copy of the exact same genetic code
Every cell in our body contains a copy of the exact same genetic code. This means that each of our cells contain every gene needed to produce every protein. BUT every cell doesn’t produce every protein - they only produce the proteins needed by their particular cell type.

8. B. The Structure of DNA 1. Looks like a twisted ladder or double helix
2. Both sides of the ladder are made of molecules of deoxyribose(sugar), alternating with phosphate molecules.

9. Building DNA Building Blocks

10. 3. Each rung of the ladder is made up with a pair of molecules called nitrogen bases:Adenine, thymine, guanine and cytosine.

11. 4. Adenine always matches up with thymine,
Guanine only pairs with cytosine

12. C. DNA Replication

13. 1. A cell makes a copy of its DNA before mitosis occurs.
2. Replication ensures that each daughter cell will have all the genetic information needed to carry out its activities.

14. A Nucleotide

15. 3. Replication starts with the two sides of the DNA molecule unwinding and separating.
4. The molecule separates between the paired nitrogen bases
5. Nitrogen bases floating around in the nucleus
pair up with bases on each half of the chromosome.

16. 3. Replication starts with the two sides of the DNA molecule unwinding and separating.
4. The molecule separates between the paired nitrogen bases
5. Nitrogen bases floating around in the nucleus
pair up with bases on each half of the chromosome.

17. D. History of Science
1. In the 1950s, DNA was identified as the carrier of genetic information.
2. Rosalind Franklin conducted
x-ray diffraction studies of the DNA molecule in 1951, which suggested DNA had a helical structure.

18. 3. At the same time James Watson and Francis Crick were exploring how DNA functioned.

19. 4. They realized that the
form of a double helix would not only explain
the shape of DNA, but explain how the
molecule passes on genetic information.

20. 5. After physically building a model of their proposed structure, they realized they had solved the riddle of how genetic information is transmitted.

21. 6. In 1962, Watson, Crick and another researcher Maurice Wilkins, received the Nobel Prize for their discovery.
7. Unfortunately, Rosalind Franklin's death in 1958 at age 38 prevented her from sharing in their recognition.