Biology - HOT Science Lab

Teacher
After
activity:
d. Students may also not be paying attention to the direction in which the
complementary strand is going. Even though it is not assessed, an
understanding of how a complementary strand in DNA is oriented (5‘, 3‘
direction) should be reviewed.
e. Another student misconception and important factor in DNA replication is
the importance of enzymes in a DNA model in order to allow for its
unzipping in the replication process. Without these restriction enzymes,
replication would not occur. Have the students model the ―cutting‖ of the
hydrogen bonds in their DNA model, using their restriction ―enzymes‖
(scissors).
f. Students also need to understand that these enzymes are actually proteins
in the body. When macromolecules are taught, restriction enzymes can be
applied to the content as an example of a protein.
g. Students should be drawing every stage of their modeling process into their
journals and label what is occurring at every point. Use these observations
for your assessments.
What the teacher will do:
a. Ensure the students clean up their models. You may choose to have them
store it with plastic wrap in order to use them on assessments or during
discussions.
b. Have the students complete the following ―Data Analysis‖:
1. What is the function of DNA (to preserve genetic information in the cell)
2. Why is it so important that the order of base pairs stays the same (to
ensure that the sequence of the genetic code stays the same and to
prevent mistakes from occurring in cell division)
3. What would happen if there was a change in the base pair sequence
(Changes in the DNA sequence can cause a mutation in the individual
proteins of an organism causing problems such as cancer or
uncontrolled cell growth. These mutations can also become new
variations in a species if they are carried on.)
4. What special proteins make replication of DNA possible (Enzymes
allow the unzipping of a DNA strand in order to allow it to be replicated.)
5. What is the difference between replication and duplication (Replication
is a complimentary copy of the strand of DNA, filling one side to its
matching pairs. Duplication would mean exact copy of the original
bases)
6. At which stage of cell division (mitosis) does replication take place
(During the Synthesis phase before Mitosis)
c. Discuss your results and your analysis questions with the rest of the class
in a whole group discussion. Determine as a class what might be the
prevailing factor in the amount of DNA extracted. Design a simple
experiment that would test these factors.
Extension:
Gizmo: DNA Fingerprinting Analysis
Biology HSL Page 204
Curriculum and Instruction