We have seen detectives on
TV and movies getting
excited about finding hair
or skin or other body cells
on the crime scene. Why?
Exactly the same DNA is
contained in every single
cell in our bodies! Have
you ever wondered how
that is possible?
Cells are capable of giving
rise to a new generation
of cells by undergoing
DNA replication and cell
division. We are going to
study how DNA is
replicated so that each
new cell gets the same
copy in its nucleus.

Lesson 1: Discovery of DNA: A Review
 Scientists and experiments leading to the discovery of
DNA

Lesson 2: DNA Structure: A Review
 The Chemical Composition of DNA, The Double Helix

Lesson 3: DNA Replicates Semi-Conservatively
 The Meselson and Stahl Experiment

Lesson 4: The Process of DNA Replication
 Separating the DNA Strands, Building the
Complementary Strands, DNA Repair

Lesson 5: Assessment
Overall Expectations
D2. investigate, through laboratory activities, the structures of
cell components and their roles in processes that occur within
the cell;
D3. demonstrate an understanding of concepts related to
molecular genetics, and how genetic modification is applied
in industry and agriculture.
Specific Expectations
D2.2 analyse a simulated strand of DNA to determine
the genetic code and base pairing of DNA (e.g., determine
base sequences of DNA for a protein; analyse base
sequences in DNA to recognize an anomaly) [AI]
D3.1 explain the current model of DNA replication, and
describe the different repair mechanisms that can correct
mistakes in DNA sequencing
Scientists such as Hammerling, Griffith,
Hershey and Chase, Chargaff, Franklin
and Wilkins, Watson and Crick
conducted experiments that led to
better understanding of DNA and its
structure. Slides with M/C questions and
clickers may be used to review this
information with the students.
 Students complete a DNA timeline
scavenger hunt at

› http://www.dnai.org/timeline/index.html

Students are shown the following video
› http://www.youtube.com/watch?v=ZGHkHMoyC5I


Students build DNA molecules in pairs (Activity # 1)
Teacher goes over discussion questions with the
class. Any gaps in knowledge are filled and
misconceptions are corrected.

What is semi-conservative replication?
› What do you notice?
› Based on your knowledge of DNA structure, how
do you think this occurs?

Hypothesis
Conservative

Semi-Conservative
Dispersive
Objective: Is DNA replication conservative, semiconservative or dispersive?
Meselson and
Stahl Experiment
(Continued)



Experiment explained
using overhead
Following animation
explaining experiment
shown:
› http://highered.mcgr
awhill.com/olc/dl/12007
6/bio22.swf
Students complete the
virtual lab and assessed
(quiz #1)
› http://www.sumanasi
nc.com/webcontent
/animations/content/
meselson.html
Key Enzymes: DNA Helicase, Single
Stranded Binding Proteins (SSBs), DNA
Gyrase
 Replication Fork vs. Replication Bubble



Key Enzymes: DNA Polymerase I and III, Primase,
DNA Ligase
Key Terms: RNA Primers, Leading and Lagging
Strands, Okazaki Fragments

Synthesis of Lagging Strand

Key Enzymes: DNA polymerase I and III
act as exonuclease

The students will be shown animations:
› http://highered.mcgraw-
hill.com/olc/dl/120076/micro04.swf
› http://highered.mcgrawhill.com/olc/dl/120076/bio23.swf

Whole-Class Replication Role-Play
› Each student acts as a nucleotide. Hands
are used to form bonds. (Explained fully in
summary)
1) Visual: Students will make a sketch or diagram of the process of DNA replication. (K/I)
2) Musical: Students will listen to the DNA replication song and write another verse for the
song. (K/I/C/A)
http://www.youtube.com/watch?v=dIZpb93NYlw
3) Kinesthetic: Students will design an explanation for DNA replication using body/hand
actions. (K/I/C/A)
4) Linguistic: Students will imagine being a DNA molecule and write a story explaining how
they are copied. (K/I/C)
5) Intrapersonal: Students will write explaining what they found to be fascinating about DNA
replication. (K/I/C/A)
6) Interpersonal: Students will explain their understanding of DNA replication to their partners.
(K/I/C)
7) Logical: Students will perform the DNA replication gizmo at
http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=439
Students will be given a copy of the ‘Student Exploration Sheet’ found on the website.
(K/I/C/A)
Summative Assessment will take place at the end of the genetics unit in the form of a Unit
Test.
The students may find it difficult to understand the
procedure and conclusions of the Meselson and Stahl
experiment
•
•
Explain each step in detail using illustrations and drawings
The students may have a difficult time visualizing the
concept of DNA replication
•
•
Show the animations multiple times
The students may have difficulty keeping track of all the
enzymes involved in replication
•
•
Create a word wall with all the important terms
The students may get confused about the lagging strand
replication
•
•
Emphasize that DNA strands are antiparallel and DNA
polymerase III synthesizes only in the 5’ to 3’ direction.
The following tutorial can be used to reiterate concepts:
http://www.wiley.com/college/pratt/0471393878/student/ani
mations/dna_replication/index.html
•




Model building, role play and animations will help the entire
class including ELL and special needs students to visualize the
abstract structure of DNA.
Posting a word wall with the new vocabulary related to DNA
structure and replication process will help the ELLs and
special need students in writing tasks.
Extra attention and time will be given to ELLs and special
needs students during classroom discussions and in computer
lab.
Peer assistant will be encouraged in the classroom
assignments by heterogeneous grouping of students.
•
DNA analysis can be used to:
• Solve crimes (homicide)
• Identify human remains (missing persons,
disasters)
• Determine relationship between family
members (paternity, child abductions)
• Medical Research (genetic diseases, drugs)
• Agriculture and Horticulture (genetically
modified organisms)
• Animal Husbandry (genetically modified
animals)
Thomson Nelson Limited. (2003). Biology 12. Toronto, Ontario: Author.
This textbook was the source for background information and was also used for
organizing the lessons.
http://www.accessexcellence.org/RC/AB/WYW/wkbooks/SFTS/activity2.php
This website was used to form Activity # 1 that is used in reviewing DNA
composition and structure.
http://highered.mcgraw-hill.com/olc/dl/120076/bio22.swf
This animation was used to explain the Meselson and Stahl Experiment.
http://www.sumanasinc.com/webcontent/animations/content/meselson.html
This virtual lab was used as assessment for the Meselson and Stahl Experiment.
http://highered.mcgraw-hill.com/olc/dl/120076/micro04.swf
http://highered.mcgraw-hill.com/olc/dl/120076/bio23.swf
These animations were used in summarizing DNA Replication
http://www.youtube.com/watch?v=dIZpb93NYlw
This video shows the DNA replication song that was part of assessment.
http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&Resour
ceID=439
This gizmo was used as an assessment tool at the end of the lessons.
http://www.wiley.com/college/pratt/0471393878/student/animations/dna_replicat
ion/index.html
This tutorial was used to clear any student misconceptions and reiterate the whole
process of DNA replication