BIO-1120: Chapter 16

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BIO-1120: Chapter 16
2015-01-03 21:45:52
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  1. Antiparallel
    Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5' -> 3' directions)
  2. Bacteriophage
    a virus that infects bacteria; also called phage
  3. Chromatin
    the complex of DNA and proteins that makes up eukaryotic chromosomes. when the cell is not dividing, chromatin exists in its dispered form, as amass of very long, thin fibers that are not visible with a light microscope
  4. DNA Ligase
    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)
  5. DNA Polymerase
    an enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucelotides to the 3' end of an existing chain. There are serveral different DNA polymerases; DNA polymerase III and DNA polymerase I play major roles in DNA replication in E. coli.
  6. DNA Replication
    the process by which a DNA molecule is copied; also called DNA synthesis
  7. Double Helix
    the form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape
  8. Euchromatin
    the less condensed form of eukaryotic chromatin that is available for transcription
  9. Helicase
    an enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands
  10. Heterochromatin
    eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed
  11. Histone
    a small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in chromatin structure
  12. Lagging Strand
    a discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' -> 3' direction away from the replication fork
  13. Leading Strand
    the new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5' -> 3' direction
  14. Mismatch Repair
    the cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides
  15. Nuclease
    an enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides
  16. Nucleosome
    the basic, bead-like unit of DNA packing in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone
  17. Nucleotide Excision Repair
    a repair system that removes and then correctly replaces a damaged segmentof DNA using the undamaged strand as a guide
  18. Okazaki Fragment
    a short segment of DNA synthesized away from the repluication fork on a template strand during DNA replication. Many such segments are joine dtogether tog make up the lagging strand of newly synthesized DNA
  19. Origin of Replication
    site where the replication of DNA molecule begins, consisting of a specific sequence of nucleotides
  20. Phage
    a virus that infects bacteria; also called a bacteriophage
  21. Primase
    an enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA strand as a template
  22. Primer
    a short stretch of RNA with a free 3' end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication
  23. Replication Fork
    A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized
  24. Semiconservative Model
    type of DNA replication in which the replicated double helix consisting of one old strand, derived from the parental molecuke, and one newly made strand
  25. Single-Strand Binding Protein
    a protein that binds to the unpaired DNA strands during DNA replication, stablizing them and holding them apart while they serve as templates for the ynthesis of complementary strands of DNA
  26. Telemere
    the tandemly repetitive DNA at the end of a eukaryotic chromosome's DNA molecule. Telomeres protect the organism's genes from being eroded during successive rounds of replication
  27. Topoisomerase
    a protein that breaks, swivels, and rejoins DNA strands. During DNA replication, topoisomerase helps to relieve strain in the double helix ahead of the replication fork
  28. Transformation
    (1) the conversion of a normal cell into a cell that is able to divide indefinitely in culture, thus behaving like a cancer cell. (Malignant transofmration may also describe the series of changes in a normal cell in an organism that change it into a malignant (cancerous) cell.) (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell.When the external DNA is from a member of a different speicies, transformation results in horizontal gene transfer