Term
| Explain Griffith's contribution to early genetic exploration. |
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Definition
| Griffith discovered the process of transformation in his experiment with two bacteria strains. He noticed that the dead pathogenic bacteria cells could convert living pathogenic bacteria into the harmful (pathogenic) strain. |
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Term
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Definition
| A change in genotype and phenotype due to the assimilation of external DNA by a bacterial cell |
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Term
| Explain Avery's et al contribution to early genetic exploration. |
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Definition
| Avery identified DNA as containing genetic material, as opposed to RNA and protein, by testing each molecule's ability to transform in a sample. His discovery was not widely accepted at the time. |
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Term
| Bacteriophage (aka. phage) |
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Definition
| Virus that infects bacteria |
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Term
| Explain the Hershey and Chase experiment and its significance. |
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Definition
| Hershey and Chase provided additional evidence to show that DNA carries genetic information by using radioactive sulfur to tag protein in one virus particle and radioactive phosphorus to tag DNA in another virus particle. After allowing the virus to infect bacteria, they noticed that the radioactive phosphorus was transmitted into the bacteria cell, thus proving that DNA was the genetic material that is transmitted from virus to bacteria. |
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Term
| What are the four nitrogenous bases and their complementary pairs? |
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Definition
Adenine - Thymine
Cytosine - Guanine |
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Term
| What are Chargaff's rules? |
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Definition
| The proportion of adenines in a DNA helix is equal to the proportion of thymines, and the proportion of cytosines is equal to the proportion of guanines |
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Term
| What are the three components of a DNA strand? |
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Definition
| Deoxyribose (sugar), phosphate group, nitrogenous base |
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Term
| Explain the contributions of Watson and Crick regarding DNA structure. |
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Definition
| Watson and Crick identified DNA as having a double helical structure after examining an X-ray diffraction photograph of DNA that Rosalind Franklin took. |
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Term
| Why does the double helix structure for DNA make sense? |
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Definition
| The model works because it places hydrophobic nitrogenous bases in the molecule's interior and away from the surrounding aqueous solution. The consistent width between strands is explained by the paring of pyrimidine bases with purine bases, which are held together by hydrogen bonding. |
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Term
| Identify which bases are pyrimidines and which are purines. Which are larger? |
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Definition
Pyrimidines: C, T
Purines: A, G
Purines are larger. |
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Term
| Semiconservative Model of Replication |
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Definition
| Two daughter DNA molecules each have one parental strand and one newly formed strand |
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Term
| Conservative Model of Replication |
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Definition
| The parent double helix re-forms and the duplicated model is totally new |
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Term
| Dispersive Model of Replication |
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Definition
| All four strands of the two DNA molecules are a mixture of parental and new DNA |
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Term
| Explain Meselson's and Stahl's contributions to DNA replication. |
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Definition
| They confirmed the semiconservative model of replication by labeling parent DNA in bacteria with 15N, a heavy isotope, and placing them into a medium with 14N, a lighter isotope. Next they measured the densities of successive generations of bacteria. |
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Term
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Definition
| Location with a specific nucleotide sequence where DNA begins replicating (in both directions) |
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Term
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Definition
| Y-shaped region where the parental strands of DNA are being unwound |
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Term
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Definition
| Enzyme that untwists and separates the double helix |
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Term
| Single-strand binding proteins |
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Definition
| Proteins that bind to unpaired DNA strands for stability |
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Term
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Definition
| Enzyme that relieves strain produced from untwisting strands |
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Term
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Definition
| RNA chain that is added to the end of a parental DNA strand to initiate replication |
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Term
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Definition
| Enzyme that synthesizes the primer to form a new polynucleotide off the parental DNA template strand |
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Term
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Definition
| Enzymes that catalyze the synthesis of new DNA by adding nucleotides to a pre-existing chain |
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Term
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Definition
| Adds nucleotides to the RNA primer in the 5' -> 3' direction |
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Term
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Definition
| Replaces RNA primer with DNA on the lagging strand only |
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Term
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Definition
| Only requires one primer for synthesis because replication moves toward the replication fork; elongates continuously |
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Term
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Definition
| Elongates as a series of segments, away from the replication fork |
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Term
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Definition
| Segments of replicated DNA along the lagging strand; each fragment must be primed separately |
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Term
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Definition
| Enzyme that joins the sugar-phosphate backbones of all Okazaki fragments into a continuous DNA strand |
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Term
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Definition
| DNA polymerase removes and replaces incorrectly paired nucleotides |
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Term
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Definition
| Enzyme that cuts out gaps of DNA that contain errors |
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Term
| Nucleotide excision repair |
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Definition
| Nuclease removes damaged DNA and DNA polymerase and DNA ligase fills in the resulting gap with the correct nucleotide sequence, using the undamaged strand as a template |
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Term
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Definition
| Nucleotide sequence that is added at each end of a DNA strand to protect genes from being removed during each replication (replication results in shortening DNA strands). |
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Term
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Definition
| Enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells |
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Term
| List the multiple levels of packing in a metaphase chromosome in order of size. |
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Definition
| DNA double helix, nucleosomes, 30 nm fiber, looped domains (300 nm fiber), chromatid, chromosome |
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Term
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Definition
| Complex of DNA and protein that fits into the nucleus of a eukaryotic cell |
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Term
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Definition
| Proteins that group together with DNA strands wrapped around; first level of DNA packing |
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Term
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Definition
| "beads on a string"; histone clusters with DNA threading |
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Term
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Definition
| Large loops of 30 nm fiber that eventually are folded into the metaphase chromosome shape |
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