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| A small molecule that can covalently bind to other similar molecules to form a larger macromolecule. Compare with polymer. |
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| A molecule consisting of a five-carbon sugar (ribose or deoxyribose), a phosphate group, and one of several nitrogen-containing bases. DNA and RNA are polymers of nucleotides containing deoxyribose (deoxyribonucleotides) and ribose (ribonucleotides), respectively. Equivalent to a nucleoside plus one phosphate group. |
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| Any long molecule composed of small repeating units (monomers) bonded together. The main biological polymers are proteins, nucleic acids, and polysaccharides. |
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conducted in 1928 by Frederick Griffith, was one of the first experiments suggesting that bacteria are capable of transferring genetic information through a process known as transformation.[1][2]
Griffith used two strains of pneumococcus (Streptococcus pneumoniae) bacteria which infect mice – a type III-S (smooth) and type II-R (rough) strain. The III-S strain covers itself with a polysaccharide capsule that protects it from the host's immune system, resulting in the death of the host, while the II-R strain doesn't have that protective capsule and is defeated by the host's immune system. A German bacteriologist, Fred Neufeld, had discovered the three pneumococcal types (Types I, II, and III) and discovered the Quellung reaction to identify them in vitro.[3] Until Griffith's experiment, bacteriologists believed that the types were fixed and unchangeable, from one generation to another.
- Today, we know that the "transforming principle" Griffith observed was the DNA of the III-S strain bacteria. While the bacteria had been killed, the DNA had survived the heating process and was taken up by the II-R strain bacteria. The III-S strain DNA contains the genes that form the protective polysaccharide capsule. Equipped with this gene, the former II-R strain bacteria were now protected from the host's immune system and could kill the host. The exact nature of the transforming principle (DNA) was verified in the experiments done by
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| Hershey and Chase Experiment |
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Definition
| They studied a virus named T2 and observed how is effected the bacterium Ecoli. They began by growing Viruses in the presence of two radioactive isotopes. S35 and P32. Because they knew one thing. DNA contains Phosphorous and Proteins contain Sulfur. Also it was based on the fact that the viruses have plasmids they use to infect the host cell . The plasmids remain outside the cell the only thing that enters in the dna. so they let the viruses grow with the radioactive isotopes and then shook them up in a blende and separated the material to discover what had made it into the host cell. and this was DNA. |
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One Gene =One enzyme
•Each gene is responsible for encoding a different protein
•Most of these proteins function as enzymes |
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Meselson-Stahl
Experiment |
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Is replication semiconservative, conservative or dispersive?.... that tiss the question.
Conclusion was Semi Conservative: after two generations is which 1/2 low density DNA turned out to be 14 N strand and 1/2 intermediate-density DNA or the hybrid
See what they did is: they grew E. Coli Celss in a medium with 15 N as sole source of nitrogen for many generations. Collected samples and purified DNA.2. they transfered cells to a medium containing 14N . after cells divided one they collected samples and purified. 3. after cells have divided a second time in 14N medium, collect sample and purify DNA.4.they centigued the three samples separately. Compare the locations of the DNA bands in each sample. |
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deoxyribonucleoside triphosphate
(dNTP) |
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Definition
| A monomer that can be polymerized to form DNA. Consists of deoxyribose, a base (A, T, G, or C), and three phosphate groups; similar to a nucleotide, but with two more phosphate groups |
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