Terms : Hide Images
| 2400064 | Oswald Avery | This person worked to identify the transforming substance. He purified various chemicals from heat-killed pathogenic bacteria, then tried to transform live nonpathogenic bacteria with each chemical. | |
| 2400065 | Virus | This is a little more than DNA (sometimes RNA) enclosed by a protective coat | |
| 2400066 | Bacteriophages | These are viruses that infect bacteria. | |
| 2400067 | Phages | Bacteriophages | |
| 2400068 | Hershey-Chase Experiment | Mix radioactively labeled phages with bacteria. The phages infect the bacterial cells. Agitate in a blender to separate phages outside the bacteria from the cells and their contents. Centrifuge the mixture so bacteria form a pellet at the bottom of the test tube. Measure the radioactivity in the pellet and the liquid. | |
| 2400069 | Erwin Chargaff | This person analyzed the base composition of DNA from a number of different organisms. | |
| 2400070 | Chargaff's rules | # of A=T and # of G=C | |
| 2400071 | DNA | This is a polymer of nucleotides. | |
| 2400072 | Nucleotide | This has a nitrogenous base, deoxyribose, and a phosphate group. | |
| 2400073 | Watson and Crick | This person (these people) discovered the double helix by building models to conform to X-ray data. | |
| 2400074 | Rosalind Franklin | This person was an X-ray crystallographer and took the photo that some person (people) used to get the double-helical structure of DNA. | |
| 2400075 | Pyrimidines | The family of nitrogenous bases that have a single ring. | |
| 2400076 | Purines | The family of nitrogenous bases that have two organic rings. | |
| 2400077 | Conservative model | The parental double helix reamins intact and an all-new copy is made. | |
| 2400078 | Semiconservative model | The two strands of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand. | |
| 2400079 | Dispersive model | Each strand of both daughter molecules contains a mix of old and newly synthesized parts. | |
| 2400080 | Meselson-Stahl experiment | This tested the three models ofDNA replication by this: bacteria cutured in medium containing 15N and then is transferred to medium containing 14N. The different isotope of nitrogen was distinguishable so after DNA samples were centrifuged, one could tell which model was correct. | |
| 2400081 | Origins of replication | special sites where the replications of a DNA molecule begins | |
| 2400082 | replication fork | This is a Y-shaped region where the new strands of DNA are elongating. | |
| 2400083 | DNA polymerases | These are enzymes that catalyze the elongation of new DNA at a replication fork. | |
| 2400084 | 3' end | This is where a hydroxyl group is attaced to the 3' carbon of the terminal deoxyribose. | |
| 2400085 | 5' end | This is where the sugar-phosphate backbone terminates with the phosphate group attached to the 5' carbon of the last nucleotide. | |
| 2400086 | where DNA polymerases add nucleotides | DNA polymerases add nucleotides only to the free 3' end of a growing DNA strand. | |
| 2400087 | Which direction do DNA strands elongate | 5' -> 3' | |
| 2400088 | leading strand | This strand is made first and is made completely at one time. | |
| 2400089 | Lagging strand | This strand is made starting from the direction away from the replication fork. This is synthesized in a series of short segments. | |
| 2400090 | Okazaki fragments | These are the series of segments first synthesized in the lagging strand. | |
| 2400091 | DNA ligase | This ligates (joins) the sugar-phosphate backbones of the Okazaki fragments to create a single DNA strand. | |
| 2400092 | Primer | This is the start of a new chain and is a short stretch of RNA. | |
| 2400093 | Primase | This is an enzyme that joins RNA nucleotides to make the primer. This can start an RNA chain from scratch. | |
| 2400094 | helicase | This is an enzyme that untwists the double helix at the replication fork, separating the two old strands. | |
| 2400095 | single-strand binding protein | These line up along the unpaired DNA strands, holding them apart while they serve as templates for the synthesis of new complementary strands. | |
| 2400256 | Frederick Griffith | This person made an experiment that involved injecting mice with smooth S cells, rough R cells, heat-killed S cells, and heat-killed S cells with living R cells. | |
| 2400257 | Mice Lab | Mice were injected with pathogenic bacterium and variant bacterium. This experiment had apparently nothing to do with DNA, yet it hadeverything to do with DNA. This experiment was performed by Griffith. | |
| 2400258 | pathogenic | disease-causing | |
| 2400259 | variant | harmless | |
| 2400260 | transformation | This is a change in genotype and phenotype due to the assimilation of external DNA by a cell. |
