DNA Replication Flashcards
What is DNA replication?
MAking a copy of DNA
Why do we need DNA replication?
Cell reproduction
Watson and Crick discovery suggested what?
Base pairing suggested possible copying mechanism
What does it mean to be semiconcervative?
Half of new molecule comes from the parent DNA and the other half is synthesized
What are chromosomes?
Condensed DNA
What are the two types of chromosomes?
- Linear
2. Circular
What are the bonds between nucleotides?
H-bonds
How many chromosomes are in E. coli?
Single circular chromosome
What is the shape of a human chromosome? How many do they have?
Linear; 23 chromosome pairs
What is the origin of replication?
Where replication starts
What is the replication “bubble”?
The bubble created by splitting the H-bonds between nucleotides
What does it mean to have bidirectional replication?
Replication done on both sides of the fork
Where does new DNA attach to 3’ end of a polynucleotide?
Hydroxyl group of the 3’ C (2 PO4) are lost in process
What kind of reaction creates polynucleotides?
Dehydration Reaction
What kind of bond is created by the dehydration reaction?
Covalent phosphodiester bonds
New DNA strands elongate ONLY in _’ to _’ direction.
5’ to 3’
How do you determine if the strand is the leading or lagging strand?
Leading- toward fork
Lagging- away from fork
KNOW THE STEPS OF LAGGING AND LEADING DNA REPLICATION.
YES SIR
What is the role of helicase?
Unwind parental double helix at replication forks
What is the role of single strand binding protein?
Binds to and stabilizes single-stranded DNA until is it used as a template
What is the role of topoisomerase?
Relieves overwinding strain ahead of replication forks by breaking, swiveling, and rejoining DNA
What is the role of primerase?
Synthesizes an RNA primer at 5’ end leading strand and at 5’ end of each Okazaki fragment lagging strand
What is the role of DNA polymerase III?
Using parental DNA as a template, synthesizes new DNA strand by adding nucleotides to an RNA primer or a preexisting DNA strand
What is the role of DNA polymerase I?
Removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides added to 3’ end of adjacent fragment
What is the role of DNA ligase?
Joins Okazaki fragments of lagging strand; on leading strand, joins 3’ end of DNA that replaces primer at reset of leading strand DNA.
Explain the “trombone” model of the DNA Replication Complex.
The proteins are not the moving part of this process. The DNA will move through the proteins as the replication process progresses
What are Okazaki fragments?
RNA/DNA fragments created in the lagging strand of DNA replication
