8.2 Flashcards
What is the function of Helicase in DNA replication?
Seperates the DNA into two strands
Helicase unwinds the double helix structure of DNA, allowing replication to occur.
What role does Primase play in DNA replication?
Adds RNA primers
Primase synthesizes short RNA sequences that serve as starting points for DNA synthesis.
What is the primary function of DNA Polymerase III?
Adds nucleotides to produce new DNA strands
DNA Polymerase III is responsible for the bulk of DNA synthesis during replication.
What is the role of DNA Polymerase I in DNA replication?
Removes RNA primers and replaces them with DNA nucleotides
DNA Polymerase I ensures that RNA primers are replaced with DNA, maintaining the integrity of the new DNA strand.
What does Ligase do in the DNA replication process?
Connects DNA fragments together
Ligase seals nicks in the sugar-phosphate backbone of the DNA, joining Okazaki fragments on the lagging strand.
What is the goal of DNA replication?
To make an identical copy of DNA for each new cell.
What do the arrow ends of the DNA model indicate?
They point in opposite directions.
What do the 3’ and 5’ carbons represent in DNA?
They are used to distinguish carbons on the sugar portion of the nucleotide.
How are the 3’ and 5’ carbons oriented in the DNA strands?
5’ - 3’.
What is the approximate rate of nucleotide addition in eukaryotic cells?
50 nucleotides per second.
Why do multiple replication bubbles form during DNA replication?
To speed up the replication process.
What is the role of helicase in DNA replication?
It separates or unzips the DNA.
Which type of bond does helicase break during DNA replication?
Hydrogen bonds.
Why is helicase able to break hydrogen bonds?
Because hydrogen bonds are weaker than covalent bonds.
What is the function of DNA polymerase during replication?
It catalyzes the synthesis of new DNA by adding nucleotides.
What is the leading strand in DNA replication?
The DNA strand that is made continuously.
What is the lagging strand in DNA replication?
The strand that is synthesized in fragments (Okazaki fragments).
What must occur when DNA polymerase bumps into the first fragment on the lagging strand?
Remove the DNA polymerase and join the two fragments together.
Why is DNA replication considered to be a semi-discontinuous process?
Because replication occurs continuously on the leading strand and discontinuously on the lagging strand.
Fill in the blank: Nucleotides are added to the DNA strand in the ______ direction.
5’ → 3’.
What are Okazaki fragments?
Short DNA fragments synthesized on the lagging strand.
What is the total number of nucleotides in the human genome?
6.4 billion nucleotides.
How long would it take to copy the human genome if only one base is copied at a time?
Approximately 1421 days.
What is the first step in the process of DNA replication?
Feeding the strands of DNA into the helicase enzyme.
What is the importance of labeling the 3’ and 5’ ends during DNA replication?
To ensure correct orientation and directionality during synthesis.
True or False: DNA replication occurs in only one direction.
False.
