DNA and Protein Synthesis
1. Answer the following questions:
X-rays damage DNA in organisms. Rosalind Franklin died of cancer at an early age. How might her work with X-ray diffraction have led to her death?
- X-rays can be harmful and cancer-causing agents. The radiation could have contributed to her cancer by mutating her DNA over the long period of time she spent exposed to x rays in the lab.
A scientist extracted 4.6 picograms (or 4.6 x 10-12 grams) of DNA from mouse muscle cells. How much DNA could be extracted from the same number of mouse kidney cells and the same number of mouse sperm? Explain your answer.
- 4-6 picograms from mouse kidney cells, but 2-3 picograms from mouse sperm. The amount of DNA in each normal cell is always the same. Muscle cells and kidney cells both have the same amount of DNA. Sperm cells only contain one copy of each chromosome, so the same number of cells contains half as much DNA.
2. In a few sentences, explain how the structure of DNA is similar to that of a ladder. How is it different? - Nucleotides are the subunits that make up DNA. Each nucleotide is made of three parts: a phosphate group, a five-carbon sugar molecule, and a nitrogen-containing base. While the sugar molecule and the phosphate group are the same for each nucleotide in a molecule of the DNA, the nitrogen base may be any one of four different kind: Adenine, Guanine, Thymine, Cytosine. The DNA shown resembles a ladder twisted like a spiral staircase. The sugar-phosphate backbones are similar to the side rails of a ladder. The paired nitrogen bases are similar to the rungs of the ladder. The nitrogen bases face each other. The double helix is held together by weak hydrogen bonds between the pairs of bases.
X-rays damage DNA in organisms. Rosalind Franklin died of cancer at an early age. How might her work with X-ray diffraction have led to her death?
- X-rays can be harmful and cancer-causing agents. The radiation could have contributed to her cancer by mutating her DNA over the long period of time she spent exposed to x rays in the lab.
A scientist extracted 4.6 picograms (or 4.6 x 10-12 grams) of DNA from mouse muscle cells. How much DNA could be extracted from the same number of mouse kidney cells and the same number of mouse sperm? Explain your answer.
- 4-6 picograms from mouse kidney cells, but 2-3 picograms from mouse sperm. The amount of DNA in each normal cell is always the same. Muscle cells and kidney cells both have the same amount of DNA. Sperm cells only contain one copy of each chromosome, so the same number of cells contains half as much DNA.
2. In a few sentences, explain how the structure of DNA is similar to that of a ladder. How is it different? - Nucleotides are the subunits that make up DNA. Each nucleotide is made of three parts: a phosphate group, a five-carbon sugar molecule, and a nitrogen-containing base. While the sugar molecule and the phosphate group are the same for each nucleotide in a molecule of the DNA, the nitrogen base may be any one of four different kind: Adenine, Guanine, Thymine, Cytosine. The DNA shown resembles a ladder twisted like a spiral staircase. The sugar-phosphate backbones are similar to the side rails of a ladder. The paired nitrogen bases are similar to the rungs of the ladder. The nitrogen bases face each other. The double helix is held together by weak hydrogen bonds between the pairs of bases.