1. Nucleoside have only a sugar and nitrogen base. (whereas nucleotides have sugar, nitrogen base, and phosphate group.)
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| There is a hydroxyl (-OH group) in the structure of RNA. |
2. RNA is more reactive than DNA because it is single stranded and it has one extra oxygen. This means that it cannot form a double helix strcuture because of the extra oxygen bond. The oxygen bond will react with something, such as the nearby phosphate group, and break the ladder structure if the RNA where to create a helix structure.
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| A portion of a DNA molecule with the helix unwound, showing the complementary base pairs. |
3. In base pairing, adenine and thymine always bind together (double hydrogen bonds) and guanine and cytosine bind together (triple hydrogen bonds).
4. There are three types of nucleotide bonds:
- Glycosyl - sugar + nitrogenous base (intramolecular)
- Phosphodiester - sugar + phosphate (intramolecular)
- Hydrogen - between nitrogenous bases (bonds connecting the nucleotides and nucleosides) (intermolecular)
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| Friffith's experiment proving that DNA is genetic material. |
5. Discovery of the genetic code began with research by Frederick Griffith in 1928. He discovered transformation, which is a change in genotype and phenotype due to the assimilation of a foreign substance by a cell. Through his experiments, it was proven that protein was not the hereditary material.
6. REPLICATION Summary:
Acts | Names | Characters | Roles |
| I | Initiation | -Helicase -SSBP -Gyrase -Primase | -Untwists DNA, provides the direction of replication -Stabilizes single stranded DNA -Release tension -Makes primers to initiate elongation |
| II | Elongation | -DNA Pol. III | -Elongates new DNA strands -Replication (5’-3’) |
| III | Termination | -DNA Pol. I -Ligase | -Proofreads the new strand (replace RNA with DNA) -Joins gaps between okazi fragments |
7. Ribosomes are composed of 30 and 50 subunits (70s total) in prokaryotes, 40 and 60 subunits (80s total) in eukaryotes.
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| Exons are excised (cut out) before translation. |
8. RNA splicing removes introns (the noncoding segments) and joins exons to creat an mRNA molecule.
9. Three ways in which DNA can be replicated:
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| Possible ways DNA is replicated in. The two original strands of DNA are shown in yellow (light); newly synthesized DNA is blue (dark). |
Dispersive replication would produce two DNA molecules with sections of both old and new DNA interspersed along each strand.
Semiconservative replication would produce molecules with both old and new DNA, but each molecule would be composed of one old strand and one new one.
10. DNA replicates 5' to 3'.
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