DNA Replication Flashcards
1
Q
Step 1 of DNA Replication
A
DNA must unwind to expose a single stranded template
2
Q
What does helicase do?
A
- Unzips and unwinds the double helix
- Breaks hydrogen bonds
3
Q
What enzymes are used in step 1 of DNA replication?
A
- Helicase
- Toposiomerase (gyrase)
4
Q
What does topoisomerase (gyrase) do?
A
- Detangler
- Prevents supercoils by nicking and resealing DNA
5
Q
Step 2 of DNA Replication
A
DNA must be held open, not to reform a coil
6
Q
What do Single Stranded Binding Proteins do?
A
- Bind to the uncoiled DNA and keep it open
7
Q
Step 3 of DNA Replication
A
A primer must be created before DNA synthesis can occur
8
Q
What is a primer?
A
- Short sequence of RNA, complementary to template
- Provides 3’ end where DNA synthesis can begin
9
Q
What is primase?
A
Enzyme that synthesizes RNA primer
10
Q
What is RNA polymerase?
A
- Synthesizes primers on leading strand
- Type of RNA polymerase
11
Q
Leading strand
A
- New strand that is synthesized continuously
- Synthesized towards replication fork
12
Q
Lagging Strand
A
- Synthesized in short fragments called Okazaki fragments which are later joined together
- Discontinuously
- Synthesized away from replication fork
13
Q
Step 4 of DNA Replication
A
DNA synthesis begins
14
Q
What is DNA polymerase 3 (builder)
A
- Enzyme that catalyzes the addition of nucleotides complementary to the template strand
15
Q
What direction does DNA synthesis occur in?
A
5’ to 3’ direction
