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Biology DNA#2
| Term | Description |
|---|---|
| Frederick Griffith | A British medical officer, made an observation that "some chemical substance" transferred from the dead bacteria to the living cells by studying and experimenting on two strains of pneumococcus bacteria. |
| Transformation | A type of permanent genetic change in which the properties of one strain of dead cells are conferred on a different strain of living cells. |
| Avery, MacLeod, and McCarty | Identified the transforming principle as DNA. They did this through a series of experiments in which they lysed the S cells, separated the organelles, and then tested each fraction to see if it could transform living R cells into S cells. |
| Hershey and Chase | Experimented on bacteriophages with isotopes 35 S and 32 P to test if DNA is used in reproduction. |
| Franklin | Produces an X-Ray diffraction image of DNA |
| Watson and Crick | Proposes a model of the structure of DNA. |
| DNA building block | Composed of Nitrogenous Base, 5 Carbon Sugar, and a phosphate. |
| Nitrogenous Bases | Attached to the 1' carbon of the sugar. Include adenine, guanine, thymine, and cytosine. |
| Purines | Composed of adenine and guanine. |
| Pyrimidines | Composed of thymine and cytosine. |
| Nucleotides | DNA building block. Nucleotides are linked by covalent bonds. The phosphate group has an ester bond to the 5 carbon sugar. The 5 carbon sugar has a glycosidic bond to the nitrogenous base. |
| Phosphodiester linkage | A bond between the 3' Carbon of one sugar to the 5' Phosphate of the adjacent sugar. |
| 5' end | Has a 5' Carbon attached to a phosphate |
| 3' end | Has a 3' carbon attached to a hydroxyl group. |
| Chargaff's Rule | States that the ratios of purines to pyrimidines and also of adenine to thymine and of guanine to cytosine were close to one. |
| Antiparallel | The two strands of DNA runs in opposite directions. |
| Complementary sequence | The sequences of nucleotides in one chain dictates the complementary sequence of nucleotides in the other. "3'--AGCTAC--5' and 5'--TCGATG--3'" |
| DNA Replication | A process in which the sequences of nucleotides in DNA could be precisely copied. |
| Semiconservative Replication | A model in which the hydrogen bonds between the two strands would break and the two chains to separated. Each strand could then pair with new complementary nucleotides to replace its missing partner. The result is two DNA identical to the original, w/ 1P |
| Conservative replication | Both parent strands would remain together, and the two newly synthesized strands would form a second double helix. |
| Dispersive replication | The parental and newly synthesized strands might become randomly mized during the replication process. |
| DNA replication w/ mutation | When the DNA molecule containing an error replicates, one of the strands gives rise to a molecule exactly like its parent strand; the other mutated strand gives rise to a molecule w/ a new combination of bases that is transmitted to future generations. |
| DNA Helicases | Open the double helix by disrupting the hydrogen bonds that hold the two strands together. |
| Single-strand binding proteins (SSBs) | Also called Helix-destablizing proteins, bind to single DNA strands and stablize them; this prevents the double helix from reforming until the strands are copied. |
| Topoisomerases | Break one or both DNA strands, preventing excessive coiling during replication, and rejoin them. |
| DNA polymerase | The enzyme that catalyze the linking together of the nucleotide subunits. They add nucleotides only to the 3' end of a growing polynucleotide strand, and this strand must be paired with the strand being copied. |
| DNA Synthesis Direction | As the nucleotides link together, two of the phosphates are removed. These reactions are strongly exergonic and do not need additional energy. Therefore the new strand of DNA always grows in teh 5' ---> 3' direction. |
| DNA Primase | Synthesizes short RNA primers on the lagging strand. Begins replication of the leading strand. |
| DNA Ligase | Links Okazaki fragments by joining the 3' end of the new DNA fragment ot the 5' end of the adjoining DNA. |
| Telomerase | Lengthens telomeric DNA. This enzyme is typically present in cells that divide an unlimited number of times, and most types of cancer cells. |
| RNA primer | The sequence of about 5 RNA nucleotides that are synthesized during DNA replication to provide a 3' end to which DNA polymerase adds nucleotides. The RNA primer is later degraded and replaced with DNA. |
| Origins of replication | Specific sites on the DNA molecule where DNA replication begins. |
| Replication Fork | The Y-Shaped structure where the strands replicate |
| Leading Strand | The new strand that is growing toward the replication fork. |
| Lagging Strand | A new strand that grows in fragments away from the replication fork. |
| Okazaki fragments | The 100- to 2000- nucleotide pieces on the lagging strand. |
| DNA synthesis BiDirectional | When double-stranded DNA separates, two replication forks form, and the molecule replicates in both directions from the origin of replication. |
| Telomeres | End caps of chromosomes. Because DNA replication of eukaryotes is discontinuous in the lagging strand, DNA polymerase does not complete neatly. At the end, a small portion is left unreplicated, and a small, singled stranded segment is lost. But info kept. |
Created by:
mahn
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