Chapter 13 Flashcards
The molecular Basis of Inheritance (aka DNA Replication)
Who was Fredrick Griffth?
he discovered the phenomenum of “transformation” (mouse experiment)
What are Chargaff’s Rules?
1)DNA composition varies between species
2) for each species, %of A matches %of T, and %of C matches %G
What was the Hershey-Chase experiment?
found that DNA was genetic material (tagged proteins and DNA on viruses and let them infect E. Coli)
What is a baceriophage?
viruses that infect bacteria
What is a virus
an infection particle incapable of replicating outside of a cell
explain the structure of a DNA double helix
-the helix makes a full turn every 3.4 nM
-the bases are stacked .34nM apart
-every ten ‘rungs’, the helix creates a full turn
How are nucleic acids unique in comparison to other organic molecules?
nucleic acids have the ability to dictate their own replication from monomers
DNA replication is
the process by which a DNA molecule is replicated
(1 in 10,000,000,000 nucleotide pairs have an error)
What are the models of DNA replication? Which one is the most supported?
conservative model - a parent molecule creates an identical copy while remaining intact, resulting in 3 new daughter molecules and the original parent molecule
semiconservative model - a strand from the parent goes to each of the direct daughters, who then replicate again, so there are 4 new daughter molecs with 2 of those having a strand of the original parent in them (MOST SUPPORTED IN EXPERIMENTATION)
dispersive model - all of the resulting 4 daughter molecs have parts of the parent, in a mosaic fashion
origin of replication
stretch of DNA with a specific sequence of nucleotides that dictate where replication should occur
-eukaryotes have thousands of these to spread up the process of DNA replication
replication fork
a Y-shaped region on replicating DNA molecule where the parental strands are being unwound and new strands are synthesizing
Helicase
an enzyme that untwists the double helix of DNA at replication forks by breaking the nitrogenous base’s H-bond
Single-strand binding protiens
a protein that binds to the unpaired DNA strands during DNA replication, stabilizing and holding them apart while serving as templates for the synthesis of complementary strands of DNA
topoisomerase
a protein that breakers, swivels, and rejoins DNA strands (relieve strain in the double helix ahead of the replication fork)
what is a RNA primer?
a short polynucleotide with a free 3’ end, bound by complementary base pairing to the template strand and elongated with DNA nucleotide during DNA replication
what is primase?
a enzyme that joints RNA nucleotide to make a primer during DNA replication, using the parental DNA strand as a template
what is DNA polymerase
an enzyme that catalyzes the elongation of new DNA by the addition of nucleotides to the 3’ end of an existing chain
what is the lagging strand? what are Okazaki fragments?
the lagging strand is a discontinuously synthesized DNA strand that elongates by menas of OKazaki fragments in a 5’ -> 3’ direction (away from the replication fork)
Okazaki fragments are short segments of DNA synthesized away from the replication fork on a template strand during DNA
what is DNA ligase?
an enzyme that catalyzes the covalent bonding of the 3’ end of one DNA fragment to the 5’ end of another DNA fragment
what is the process of mismatch repair?
the cellular process that uses specific enzymes to remove and replace incorrectly paired enzymes
what is 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
what is nucleotide excision repair?
a repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide
what are telomeres?
the repetitive DNA at the ends of eukaryotic chromosome’s DNA molec; protects genes from being eroded during successive rounds of replication
what is a nucleoid?
dense regions of DNA in a bacterium that are not surrounding with a nuclear envelope
