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30 Cards in this Set

  • Front
  • Back
change in genotype and phenotype due to the assimilation of external DNA by a cell
bacteriophages (phages)
viruses that infect bacteria as a tool in molecular genetic.
DNA vs. Protein in Phage cells
DNA of the virus is injected into the host cell, while proteins remain outside. The injected DNA causes the cells to produce new viral DNA and proteins
double helix
the form of native DNA, referring to its 2 adjacent polynucleotide strands wound into a spiral shape
adenine and guanine are nitrogenous bases with two organic rings (2x as wide as pyrimadines)
thyamine and cytosine nitrogenous bases with single rings
A-T are bonded by 2 H bonds, G-C are bonded by 3 H bonds. Van der Waals attractions between the stacked pairs holds molecules together.
semiconservative model
each of the two daughter molecules will have one old strand, derived from the parent moelcule, and one newly made strand
conservative model
parent molecule remains intact and the new molecule is formed entirely from scratch
dispersive model
each strand of both daughter molecules contains a mixture of old and newly synthesized parts
origins of replication
specific sequence of nucleotides that proteins recognize and separate the strands to open the bubble.
DNA replication begins where 2 parental strands of DNA eparate to form replication bubbles. There are thousands of origin sites along the DNA molecule of each chrom that expand laterally in both directions as DNA replicates. The bubbles fuse to separate the two daughter strands.
replication fork
Y shaped region where the two strands of DNA are elongating, catalyzed by DNA polymerases
DNA polymerase
as nucleotides align complementary bases along a template strand of DNA, nucleotides are added by polymerase, one by one, to the growing end of the DNA strand
50 nucleotides/second
Energy for nucleotide addition
nucleoside triphosphate links to the sugar phosphate backbone of a growing DNA strand and loses 2 of its phosphates as a pyrophosphate molecule. hydrolysis of the bonds between the phosphate groups provides the energy for the reaction
The 5'-3' strand runs counter to the 3'-5' strand, creating distinct polarity. The 3' end has a hydroxyl group on the end, the 5' end ends with a phosphate. Nucleotides are only added to the 3' end, so DNA elongates in the 5'->3' direction.
leading strand
the new continuous completmentary DNA strand synthesized along the template strand in the 5'->3' direction
lagging strand
a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork (3'->5')
okazaki fragments
how the lagging strand grows. they individually grow in the 5'->3' direction,but work their way in in the opp. direction connected by DNA ligase (enzyme)
a short stretch of RNA that signals where replication should begin
enzyme that joins RNA nucleotides to make the primer
priming DNA synthesis
DNA polymerase cannot initiate a polynucleotide strand. After elongation, RNA is replaced with DNA
an enzyme that untwists the double heliz at the replication fork, separating the 2 old strands
single strand binding protein
line up along the unpaired DNA strands and holds them apart while they serve as templates for the synthesis of new complementary strands
mismatch repair
fixes mistakes that are made when DNA is copied. DNA polymerase proofreads each nucleotide against the template, and deletes (and replaces with the correct base) the mistake
excision repair
cutting out and replacing the DNA strand that is damaged
DNA cutting enzyme that cuts out the section of the strand with the damage. DNA polymerase and ligase re-fill this deletion
Limitations of 3' end
a gap is left at the 5' end of each new strand because DNA polymerase can only add nucleotides to a 3' end. Each round of replication results in shorted daughter strands.
special nucleotide sequences (DNA) that consists of multiple repetitions of one short nucleotide sequence AAAAAAA (polyA strand). because primer is cut out, there are extra base pairs on the template end. to make them match up, the extras must be cut out so they are made of only one base nucleotide
enzyme that catalyzes the lengthening of telomeres in gametes, so that the strands dont get shorter with each generation. has a molecule of RNA along with its protein