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36 Cards in this Set

  • Front
  • Back
DNA synthesis begins at a unique location called
origin of replication
the double helix of DNA is unwound by _____, large ATP-dependent enzyme proteins.
helicases
as the double helix is unwound, the DNA is stabilized by a
single-stranded binding protein
extensions of DNA occurs ____ on the leading strand and _____ on the lagging strand
continuously, discontinuously
most errors in base pairing are corrected by ____ functions associated with the action of ____
proofreading functions, DNA polymerase I and III
enzyme that seals "cracks" in DNA replication on the lagging strand
DNA ligase
site of replication that appears to move down the DNA
replication fork
why is proofreading important to the cell?
if there is a mispairing of bases, the base pair will be unstable
why are there leading and lagging strands?
because of the 5' > 3' direction that DNA must replicate in. since the parent strands are antiparallel, the new strands will be forming in different directions. one has to go "against the current".
RNA polymerase stops transcription at specific sites called
transcription terminators
although encoded by ___, transcription terminators function at the level of ___
DNA, RNA
some transcription terminators are ______ and require no accessory proteins beyond the polymerase
intrinsic terminators
In bacteria, trancription terminators are often ____ followed by a run of Uracils
stem-loops
what is an intrinsic terminator?
termination sites that require no accessory proteins or extra factors. usually has a G-C rich sequence followed by an A-T rich sequence which leads to termination
what is a stem-loop structure?
inverted repeats with central nonrepeating segment strand folds into a loop, pairing up the inverted repeating parts
In bacteria, promoters are recognized by the _____ of RNA polymerase
sigma subunit
promoters recognized by a specific sigma factor have ____ sequences
very similar
in the eukarya, the major classes of RNA are transcribed by ____ RNA polymerases
different
What is a consensus sequence?
the bases that occur most often in a particular position determine the consensus sequence
in a eukaryote, which type of RNA polymerase transcribes genes that encode proteins?
RNA polymerase II
RNA polymerase that synthesizes most types of rRNA
RNA polymerase I
RNA polymerase that synthesizes all the mRNA
RNA polymerase II
RNA polymerase that synthesizes tRNA, and on type of rRNA
RNA polymerase III
the three major types of RNA are:
messenger RNA, transfer RNA, and ribosomal RNA
the transcription of RNA from the DNA involves the enzyme ____, which adds bases onto 3' ends of growing chains
RNA polymerase
unlike DNA polymerase, RNA polymerase can
start a chain
RNA polymerase recognizes a specific start site on the DNA called the
promoter
RNA synthesis stops at the
transcription terminator
what is a promotor?
sites on DNA strands where RNA polymerase binds to begin a new chain
what is a transcription terminator?
a site at which trancription of RNA ends and the DNA closes into the original double helix
The unit of transcription often contains ____ gene
more than one
transcription of several genes into a single mRNA molecule may occur in ____, so the mRNA may contain the information for more than one ____.
prokaryotes, polypeptide
genes that are transcribed together from a single promoter constitute an
operon
genes encoding ribosomal RNA are _____ in both prokaryotes and eukaryoes
cotranscribed
what is messenger RNA?
an intermediary to the genes that encode proteins
what is polycistronic mRNA?
a single mRNA molecule that codes for a group of related enzymes all transcribed simulataneously.