The document outlines DNA replication, a crucial process for cell growth, repair, and reproduction, detailing its significance, stages, and key enzymes involved. It explains the three theories of DNA replication: conservative, semi-conservative, and dispersive, as well as the sequential steps of replication from unzipping the DNA to the proofreading and completion of new strands. The document emphasizes the roles of enzymes like DNA helicase, primase, polymerases, exonuclease, and ligase in the replication process.

1. DNA
REPLICATIO
N
Name: Baco, Bea O.
Program&Section: BSED-SCI
2A
Schedule: TT (8:30-11:30)
Date: 11/07/24

2. Objectives:
Explain the importance of DNA
replication.
Describe the steps involved in the
process of DNA replication.
• Identify the functions of the key
enzymes involved in DNA replication.

3. What is DNA Replication?
DNA replication is the process in
which a cell makes an identical
copy of its DNA. It is vital for cell
growth, repair, and reproduction
in organisms as it helps with the
transmission of genetic
information.

4. DNA
Is a molecule made up of two
strands twisted around each
other in a double helix shape.

5. FOUR BASES OF DNA
A (Adenine)
always pairs with
T (Thymine)
G (Guanine) always
pairs with C
(Cytosine)
A T G C
ADENINE
THYMINE
GUANINE
CYTOSINE

6. When does DNA Replication
Happen?
DNA is replicated during the S
phase of the cell cycle.

7. Where does DNA Replication
Occur?
DNA replication occurs in the
cytoplasm of prokaryotes and
in the nucleus of eukaryotes

8. Three Theories of DNA
Replication
1. Conservative Replication Model
In the conservative model, the original DNA
molecule remains completely intact, and an
entirely new, separate DNA molecule is
synthesized. After replication, one daughter
molecule would consist of both original
strands, while the other would consist of
two new strands.

9. Three Theories of DNA
Replication
2. Semi- Conservative Replication Model
The semi-conservative model proposes
that each of the two strands of the original
DNA molecule serves as a template for a
new strand. After replication, each
daughter DNA molecule has one original
strand (from the parent molecule) and one
newly synthesized strand.

10. Three Theories of DNA
Replication
3. Dispersive Model
In the dispersive model, DNA replication is
thought to occur in a fragmented way,
where each resulting strand is a mixture of
old and new DNA segments. The parent
DNA is broken into segments, and the new
DNA is interspersed with the old segments
within each strand.

11. Replication Preparation and
Beginning
Before DNA can be replicated,
the double-stranded molecule
must be “unzipped” into two
single strands.
Step 1: Replication
Fork Formation

12. DNA HELICASE
DNA helicase disrupts the hydrogen bonding
between base pairs to separate the strands
into a Y shape known as the replication fork.

13. REPLICATION BEGINS
Step 2: Primer
Binding
Once the DNA strands have been
separated, a short piece of RNA
called a primer binds to the 3’ end of
the strand. The primer always binds
as the starting point for replication.
Primers are generated by the
enzyme DNA primase.

14. REPLICATION BEGINS
Step 2: Primer
Binding

15. DNA Replication: Elongation
Enzymes known as DNA
polymerases are responsible
for creating the new strand by
a process called elongation.
Step 3 : Elongation

16. DNA
REPLICATION
FORK

17. DNA REPLICATION: ELONGATION
Step 3: Elongation

18. TERMINATION
Step 4: Termination
Completion of DNA
synthesis.
Once both the continuous and
discontinuous strands are formed, an
enzyme called exonuclease removes
all RNA primers from the original
strands

19. TERMINATION
Step 4: Termination
Completion of DNA
synthesis.
Another exonuclease “proofreads”
the newly formed DNA to check,
remove, and replace any errors.
Another enzyme called DNA ligase
joins Okazaki fragments together
forming a single unified strand

20. References
Cells can replicate their DNA precisely | Learn science at Scitable. (n.d.).
https://www.nature.com/scitable/topicpage/cells-can-replicate-their-dna-
precisely-6524830/
Khan Academy. (n.d.).
https://www.khanacademy.org/science/ap-biology/gene-expression-and-
regulation/replication/a/molecular-mechanism-of-dna-replication
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002).
DNA replication mechanisms. Molecular Biology of the Cell – NCBI
Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK26850/
Admin. (2024, July 2). DNA Replication Process with Diagrams Class 12 –
Prokaryotic & Eukaryotic DNA Replication. BYJUS.
https://byjus.com/biology/dna-replication-machinery-enzymes/