DNA Replication Flashcards
Each strand of the DNA helix is a polymer of nucleotides joined together in ___ ___ that have alternating sugar-phosphate-sugar-phosphate links. On the inside of the double helix are the complementary ___ ___ held together by ___ ___.
- phosphodiester linkages
- base pairs
- hydrogen bonds
The arrangement of the double helix is in an ___-___ fashion, meaning that one strand oriented in the 5’ to 3’ direction is directly paired to a ___ strand oriented in the 3’ to 5’ direction.
- anti-parallel
- complementary
Phosphodiester bonds involve linkage between the __ ___ ___ of the incoming nucleotide and the __ ____ of the previous nucleotide in the chain.
- 5’ phosphate group
- 3’ hydroxyl
DNA contains four bases - A,T,C, and G arranged with A paired with __ and G paired with __ on the internal portion of the double helix.
- T
- C
Hydrogen bonds stabilize these base pairs: __ for the A-T pair and ___ for the G-C pair. Thus, ___ pairs are harder to break than ___ pairs.
- two
- three
- G-C
- A-T
DNA has a ___ and a ___ groove arising from ___ ___ linkages between the deoxyribose ___ and each ___ in the double helix.
- major and a minor
- asymmetric glycosidic
- sugar
- base
DNA has three major forms -
A, B , and Z
The A and B forms are ___-__ ____, whereas the Z form is a ___-___ ____.
- right-handed helices
- left-handed helix
The B form of DNA is the ___ ___ one and contains about ___ bases per turn of the helix.
- most prevalent
- 10.5
Z-DNA may have roles in:
marking the location of genes in eukaryotic chromosomes
The A form (actually discovered by Rosalind Franklin) is more _____ and is also a right handed helix. The A form is the form assumed by ___ ___ ___ or ___-__ ____ as well.
- compressed
- double strand RNA
- RNA-DNA duplexes
____ _____ ___ is an enzyme that has three enzymatic activities.
-DNA polymerase I
What are the 3 activities of DNA Polymerase I?
- a 5’ to 3’ DNA polymerase activity to make DNA
- a 3’ to 5’ exonuclease activity (also called proofreading)
- a 5’ to 3’ exonuclease activity.
All DNA polymerases require a ____ to start ___ ____. This requirement is formed inside of cells by a special RNA polymerase known as ____. (RNA polymerase does not require a primer)
- primer
- DNA synthesis
- primase
DNA replication proceeds by ___ distinct mechanisms (both ____)- ___ on each strand.
- two
- 5’ to 3’
- one
Leading strand and lagging strand synthesis occur by different mechanisms, but both are catalyzed by the same ___ ____ ____ (___ __, in the case of E. coli).
- DNA replication complex
- Pol III
Leading strand synthesis is ____ in the __ to __ direction.
- continuous
- 5’ to 3’
Lagging strand synthesis can only occur when the leading strand synthesis ___ __ a new single stranded region for replication. The __ to __ syntheses of the lagging strand are ______.
- opens up
- 5’ to 3’
- discontinuous
The many pieces of lagging strand synthesis are called:
Okazaki fragments
To combine the okazaki fragments, the ___ _____ must be removed from each one. The 5’ to 3’ _____ ____ of DNA Polymerase I is needed to remove the initial ___ ____ of leading strand synthesis, but is needed frequently to remove the ____ of lagging strand synthesis.
- RNA primer
- exonuclease activity
- RNA primer
- primers
___ ____ is an enzyme that creates ______ bonds between adjacent nucleotides between _____ ____.
- DNA ligase
- phosphodiester
- Okazaki fragments
Biotechnologists use DNA ligase to join DNA fragments together to create:
-recombinant molecules
E. coli DNA replication occurs at ____ base pairs per second. At __ base pairs per turn, this represents a machine turning at ___ to ___ rpm.
- 1000
- 10
- 5000 to 6000
E. coli’s helicase protein (___-__: part of the __ ____) unwinds DNA at a rate of at least ____ rpm. The protein separates strands ahead of the ___ ___ __ so as to make single strands ____ for replication.
- DNA B
- BC complex
- 5000
- DNA Pol III
- accessible
