Day 1 Test 2 Flashcards
Enzyme that synthesizes DNA
DNA Polymerase
DNA Polymerase adds nucleotides at __ end of a growing DNA strand using old strand___.
Adds nucleotides at 3’ end of a growing DNA strand using old strand as a template
DNA Polymerase catalyzes formation of ____ bonds between ____ of last nucleotide in strand with ____ of incoming nucleotide
DNA Polymerase catalyzes formation of phosphodiester bonds between 3’ OH group of last nucleotide in strand with 5’ phosphate of incoming nucleotide
DNA Polymerase can only add nucleotides to a g____ DNA strand.
DNA Polymerase can only add nucleotides to a growing DNA strand (cant start a new strand from scratch)
DNA Polymerase after adding a nucleotide, DNA polymerase _____
DNA Polymerase after adding a nucleotide, DNA polymerase stays attached to chain
(T/F) The replication fork is symmetrical
False. The replication fork is asymmetrical
DNA is only synthesized in ____direction
DNA is only synthesized in 5’ to 3’ direction
At the replication fork one strand is growing overall at its ____.
At the replication fork one strand is growing overall at its 3’ end
In the leading strand DNA:
In the leading strand DNA is synthesized continuously from 5’ to 3’
In the lagging strand:
DNA is synthesized discontinuously in separate, small pieces called okazaki fragments
Okazaki fragments are synthesized ____ direction
Okazaki fragments are synthesized 5’ to 3’
On lagging strand, DNA growing in ____ direction
On lagging strand, DNA growing in 3’ to 5’ direction
On _____ strand, DNA growing in 3’ to 5’ direction
On lagging strand, DNA growing in 3’ to 5’ direction
At lagging strand, DNA polymerase is moving _____ in relation to the fork
At lagging strand, DNA polymerase is moving backwards from the fork (backstitching)
(T/F) DNA Polymerase is Self-Correcting
True
DNA polymerase has a 3’ to 5’ _____ activity
DNA polymerase has a 3’ to 5’ exonuclease activity
____ required to start synthesis of a DNA strand
Primase
Primase begins new strand by…
Primase can begin a new strand by joining 2 nucleotides together
Leading strand needs ___ primer(s)
Leading strand only needs one primer
(T/F) Leading strand needs at least 2 primers
False. Leading strand only needs one primer
Lagging strand needs ____ primer(s)
Lagging strand needs many primers – one for every okazaki fragment (about every 200 nucleotides)
Lagging strand needs ___ primer(s)
Lagging strand needs many primers – one for every okazaki fragment (about every 200 nucleotides)
Okazaki fragments are about ___ nucleotides long.
okazaki fragments are about 200 nucleotides long.
If correct nucleotide is added by DNA polymerase…
DNA polymerase adds next nucleotide
If incorrect nucleotide is added by DNA polymerase…
DNA polymerase removes incorrect nucleotide by cutting the bond then adds correct nucleotide
DNA polymerase has a _____ direction exonuclease activity
DNA polymerase has a 3’ to 5’ exonuclease activity
primase makes a short stretch of RNA about____ long is base-paired to template strand
10 nucleotides
A short stretch of RNA is called a ____.
Primer, because it provides a 3’ end for DNA polymerase to use for DNA synthesis
Primer is later removed by ____.
nucleases that recognize RNA in an RNA/DNA duplex and excise it
Gap left by removal of primer is filled by _____
DNA repair polymerase
DNA repair polymerase fills gap left by removal of primer with ______ as a primer.
DNA repair polymerase fills gap left by removal of primer with adjacent okazaki fragment as a primer.
DNA repair polymerase fills gap left by removal of primer with adjacent okazaki fragment as a _____.
primer.
___ joins together the completed fragments
DNA ligase
DNA ligase – joins together the completed fragments by …
Catalyzing the formation of phosphodiester bonds
DNA ligase – joins together the completed fragments by catalyzing the formation of phosphodiester bonds. ___ of one DNA fragment and ____ of adjacent DNA fragment
3’ OH of one DNA fragment and 5’ phosphate of adjacent DNA fragment
___ A large, multi-subunit complex present at the replication fork
Replication Machine
Replication Machine Contains… _ _ _ _ _
primase,
DNA polymerase,
helicase,
single-strand binding protein, sliding clamp
(T/F) Replication Machine complex moves along DNA to allow DNA synthesis on both strands
True, complex moves along DNA to allow DNA synthesis on both strands in a coordinated manner
In replication machine ___ moves along the DNA helix and opens it up (separate 2 strands)
Helicase
Helicase uses the energy of___
ATP hydrolysis
___ exposes the single-stranded DNA template
Helicase
___ binds to the single strands and prevents reformation of base pairs between the two original template strands
Single-strand binding protein
___ keeps DNA polymerase firmly attached to the DNA, forms a ring around the DNA
Sliding clamp
On the lagging strand DNA polymerase is ___ each time an okazaki fragment is completed
temporarily released. DNA polymerase and sliding clamp are released and may then re-associate with DNA to synthesize the next okazaki fragment
(T,F) Sliding Clamp forms a ring around the DNA
True
___ Special sequences at ends of chromosomes
telomeres are a repeated sequences that allow the ends to be replicated
__ enzyme that binds to telomeres
Telomerase
In humans the telomeres is
GGGTTA
