AP Biology-Ch 16 The Molecular Basis of Inheretance

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AP Biology-Ch 16 The Molecular Basis of Inheretance
2013-07-19 00:38:31
Biology terms

Ch 16 The Molecular Basis of Inheretance
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  1. double helix
    The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.
  2. origins of replication
    Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
  3. 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.
  4. antiparallel
    Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5′ → 3′ directions).
  5. DNA polymerase
    an enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain
  6. 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).
  7. chromatin
    The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.
  8. replication fork
    A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are growing.
  9. RNA primer
    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.
  10. RNA primase
    An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
  11. Leading strand
    The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5'?3' direction.
  12. telomere
    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. See also repetitive DNA.
  13. template strand
    The DNA strand that provides the pattern, or template, for ordering the sequence of nucleotides in an RNA transcript.
  14. helicase
    An enzyme that untwists the double helix of DNA at the replication forks, separating the two strands and making them available as template strands.
  15. 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.
  16. Okazaki fragment
    A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication, many of which are joined together to make up the lagging strand of newly synthesized DNA.
  17. Single-strand DNA-binding protein (SSBPs)
    A protein that binds to the unpaired DNA strands during DNA replication, stabilizing them and holding them apart while they serve as templates for the synthesis of complementary strands of DNA.
  18. telomerase
    An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells.
  19. semiconservative model
    Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand.
  20. nucleoid
    A dense region of DNA in a prokaryotic cell.
  21. DNA polymerase I
    5' to 3' exonuclease activity, removal of RNA primers.
  22. DNA polymerase III
    5' to 3' polymerase activity, 3' to 5' exonuclease activity (delete key)
  23. Sliding clamp protein
    oads DNA polymerase on the DNA and keeps DNA polymerase from falling. Increase processivity.