KA2- DNA replication Flashcards
Where does DNA replication occur?
The nucleus
When does DNA replication happen?
Before nuclear division
What does DNA replication ensure?
That a complete set of genetic information is passed on to new cells and the next generation
What does DNA replication produce?
Exact copies of the parent DNA molecule
Why is DNA unique?
As it can replicate itself
What is the first stage of DNA replication?
DNA unwinding
What does DNA unwinding create?
A replication fork with two template strands
What happens to the hydrogen bonds during first stage of DNA replication?
They break
What does a primer bind to?
The template strand with an exposed 3’ end
Why must a primer be present?
As DNA polymerase can only add nucleotides to an existing strand
What is a primer made of?
A short sequence of nucleotides
What replication is continuous?
The template strand that has the 3’ end
What replication strand forms the leading strand?
The one that has continuous replication
What is DNA polymerase?
The enzyme that adds individual nucleotides to the new DNA strand
How do free nucleotides line up?
Using complementary base pairing
What can DNA polymerase do?
Only add nucleotides to the 3’ end of a primer
What does DNA polymerase join?
The sugar of the primer to the phosphate of the first nucleotide
What does DNA polymerase help form?
A new strand
How does DNA polymerase continue adding nucleotides to the 3’ end of the growing strand?
Forming bonds between their sugars and phosphates
Why is the leading strand continuous?
As the process of DNA polymerase adding nucleotides to the 3’ end is repeated until the entire molecule has been replicated
What must happen to each fragment in the lagging strand?
It must be primed
Why must each fragment be primed?
To allow DNA polymerase to add nucleotides
How can DNA only grow?
By adding nucleotides to its 3’ end
What type of replication is the lagging strand?
Discontinuous
What happens once replication of lagging strand is complete?
The primer is replaced with DNA
What does DNA ligase do?
Joins the fragments together to create the lagging strand of DNA
What are the 5 requirements for DNA replication?
- DNA
- Primers
- DNA nucleotides
- Enzymes
- ATP
Why do we need ATP?
For energy
What are the enzymes we use in DNA replication?
DNA polymerase
DNA ligase
Why do we need primers?
Act as an existing chain for DNA polymerase to attach to
What is DNA replication essential for?
The continuation of life
What is DNA replication essential to ensure?
That exact copies of a specific genetic information is passed from cell to cell during growth, and from one generation till the next during reproduction
