Term
| who introduced the double hilical model for dna? |
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Definition
| james watson an dfrancis crick in 1953 |
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Term
| who discovered that genes were located on chromosomes? |
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Definition
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Term
| who discovered teh genetic role of dna? what did he study? |
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Definition
| frederick griffith in 1928. he worked with two strains of bacterium, one pathogenic and one harmless |
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Term
| what happened when griffith mixed the heat killed reamins of a pathogenic strain with the living cells of a harmless one? what did he call this phenomenon? |
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Definition
| some of the living became pathogenic. he called it tranformation, a change in genotype and phenotype due to assimilation of foreign dna |
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Term
| who discovered what the transforming substance was in griffith's experiment. why were many biologists skeptical about this discovery? |
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Definition
| Oswald Aver, Maclyn Mccarty and Colin MacLeod. little was known about dna at the time |
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Term
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Definition
| or simply phages are viruses that infect bacteria |
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Term
| who showed that dna is the genetic matierial of a phage known as T2? |
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Definition
| alfred hershey and martha chase |
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Term
| who reported that dna composition varies from one species to teh next? what did this do for dna as a genetic material? |
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Definition
| erwin chargaff in 1950. it made dna a more credible candidate for genetic material. |
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Term
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Definition
| in any species there is an equal number of A and T bases, and an equal number of G and C bases |
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Term
| who studied teh molecular structure of dna with x ray crystallogrophy? |
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Definition
| maurice wilkins and roalind franklin |
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Term
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Definition
| two strands of dna coiling making a two spirals |
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Term
| who concluded that there were two antiparallel sugar-phosphate backbones with nitrogenous bases paired in teh molecule's interior? |
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Definition
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Term
| what is watson and crick's semiconservative model? |
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Definition
| when a doubel helix replicates, each daughter molecule will have one old strand derived or conserved from teh parent molecule and one newly made strand |
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Term
| whose experiments suppored teh semiconservative model? |
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Definition
| matthew meselson and franklin stahl's |
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Term
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Definition
| site where replication begins. the two dna strands seperate opening up a replication bubble |
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Term
| explain replication role of the replication bubble in eukaryotic chromosome replication. |
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Definition
| hundreds or even thousands of bubbles form and seperate the strand in both directions from each origin until entire molecule is copied |
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Term
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Definition
| the ends of replication bubbles, a y shaped region where new dna strands are elongating |
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Term
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Definition
| enzymes that untwist the double helix at the replication forks |
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Term
| single strand binding protein |
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Definition
| this protein binds to and stablizes single stranded dna until it can be used as a template |
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Term
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Definition
| corrects overwinding ahead of replication forks by breaking, swiveling, and rejoining dna strands |
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Term
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Definition
| a short stretch of rna with a free 3' end, bound by complementary base pairing to the template strand, that is elongated with dna nucleotides during dna replication |
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Term
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Definition
| enzyme that joins rna nucleotieds to make the primer using the parental dna strand as a template |
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Term
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Definition
| catalyze teh elongation of new dna at the replication fork |
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Term
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Definition
| the new complementary dna strand synthesized consinuously along the template strand toward the replication fork in the mandatory 5' --> 3' direction |
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Term
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Definition
| a discontinuously synthesized dna strand that elongates by means of okazaki fragments, each synthesized in a 5' --> 3' direction away from the replication fork |
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Term
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Definition
| a short segment of dna synthesized away from the replication fork on a template strand during dna replication, many of which are joind together to make up the lagging strand of newly synthesized dna |
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Term
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Definition
| a linking enzyme essential for dna replication; catalyzes the covalent bonding of the 3' end of one dna fragment (such as an okazaki fragment) to the 5' end of another dna fragment ( such as a growing dna chain) |
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Term
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Definition
| repair enzymes correct erros in base pairing |
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Term
| nucleotide excision repair |
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Definition
| a nuclease cuts out and replaces damaged stretechs of dna. it cuts in such a way that it can immortalize mutations |
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Term
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Definition
| the tandemly repetitive dna at the end of a eukaryotic chromosome's dna molecule that protects the organism's genes from being eroded during successive rounds of replication. TTAGGG |
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Term
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Definition
| catalyzes the lengthening of telomeres in germ cells |
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Term
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Definition
| change in genotype or phenotype due to assimilation of foreign dna |
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Term
| what's requires more energy to break, adenine and thymine or guanine and cytosine and why? |
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Definition
| guanine and cytosine requires more energy to break because they have more hydrogen bonds |
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Term
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Definition
| region in bacteria where is found dna in a supercoild state |
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Term
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Definition
| complex of dna and protein found in the nucleus of eukaryotic cells |
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Term
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Definition
| proteins that are responsible for packagine teh first level of dna in chromatin |
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Term
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Definition
| beads formed when dna winds around histones. nucleosomes are strung together like beads on a string by lnker dna. 10 - nm fiber |
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Term
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Definition
| interactions between nucleosomes cause the thin fiber to coil or fold into this thicker fiber |
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Term
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Definition
| the 30 nm fiber forms looped domains that attach to proteins |
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Term
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Definition
| the loops domains that further coil. the width of a chromatid is 700 nm |
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Term
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Definition
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Term
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Definition
| highly condensed chromatin |
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