Introducing Nucleotides
A. Lesson Objectives: Students will learn the three basic building parts of each nucleotide and identify
elements of base pairing.
B. Target Grade Level: 10th
C. Science TEKS 6A: The student knows the structures and functions of nucleic acids in the mechanisms of
genetics; describe components of deoxyribonucleic acid (DNA)
D. Time Frame: 120 minutes
E. Attachments: DNA Extraction Lab, DNA Extraction Materials List, Discovering DNA Structure
Directions and Nucleotides, Vocabulary Self-Rating, Word Wall Graphic Organizer, Text selection,
Interpreting Graphics, DNA Concept Map
5E Model
I. Engage:
(30 minutes)
Activity
Students will extract the DNA from
wheat germ following a basic procedure.
The “Big Idea” to guide the activity and
discussion may be, “Is it possible to
extract or pull out DNA from cells and
see it?”
Students will complete the “After
Engage” column of the Vocabulary SelfRating worksheet (Carr, et al., pg 103).
Upon completion of the Vocabulary SelfAssessment the teacher should check for
prior knowledge—Do you know what
DNA is?—with a thumbs up/thumbs
down survey of the class. Then provide a
summary of DNA to refresh students’
memory.
II. Explore:
(15 minutes)
Each student will receive an “Exploring
DNA Structure” handout and color-coded
nucleotide. Students should spend 10
minutes collecting information,
completing the worksheet and assembling
the four bases. An additional 5 minutes
should be spent assembling the DNA
helix.
Modifications: Students may be given the
base pairs printed out on clear acetate;
collect observations regarding bonding,
shape; and create the helix.
Independent student work covering this
topic may be given through the “DNA
Origami” activity. This modeling activity
is time intensive and assumes an
understanding of basic chemistry.
Rationale
The lab provides a concrete experience with
DNA by allowing students to visualize
actual DNA from a plant and qualitatively
determine that organisms and cells contain a
large amount of DNA. As the students are
going through the lab, the teacher should
keep a log of terms that the students are
using to describe what they see or think is
happening. This list will be utilized during
the explanation portion of the lesson.
Throughout the lesson add the terms that
you record onto the physical word wall for
reference.
Students will complete a Vocabulary SelfRating to track their understanding of key
terms of the lesson and to inform the
teacher of the students’ perceived prior
knowledge.
This activity guides students to the
understanding of the base-pairing rules. The
bonding is conceptualized by the two
different “lock and key” shapes that are
unique to each base pair. This leads towards
future conversations regarding the double
and triple bonds formed. Again, terms used
by students should be noted for the next
portion of the lesson.
The modifications vary depending upon the
degree of implementation. Students with a
stronger chemistry background may infer
the answers to the “Discovering DNA
Structure” worksheet. Students that were
absent or in need or remediation may
complete the DNA Origami Activity.
Introducing Nucleotides
III. Explain:
(15 minutes)
The teacher will focus the class attention
on the terms collected during the first two
portions of the lesson sequence (which
are posted on the word wall). Each pair is
assigned a term or description and asked
to explain what they meant when they
used the term; write the explanation on
the white boards. Students will share-out
their understanding of the terms with the
class. Through this discussion the
students and teacher will enhance the
vocabulary wall and record this
information in their notebook.
The explanation portion of the lesson is an
opportunity for students to help each other
create an understanding of the concepts
viewed earlier in the lesson. Basic
descriptions and terms from the Engage and
Explore section are divided up amongst the
class. The goal of this activity is to help
students assign scientific vocabulary,
terminology, or descriptions to their
experiences. Students have the opportunity
to create a statement, revise it, and then
share with the class in a less intimidating
manner. As the students share out, the word
wall is created and the students copy the
information down in their notebooks or
graphic organizers.
IV. Extend:
(30 minutes)
In pairs or individually, students will read
the DNA Concept Map Worksheet. They
will then organize the vocabulary term
cards on the table in a manner that has
meaning to them. (5 minutes)
Students have the opportunity to apply their
new knowledge. By applying the new
science vocabulary to the reading selection
students begin to develop a deeper
understanding of nucleotides. To give more
purpose to the text selection, the students
are informed that they will be reorganizing
their vocabulary term cards into a concept
map. Students that are behind or were
absent may use the word wall to construct
initial connections between the terms. The
final draft of their concept map will be
copied into their science journal.
Students will read from the text pg 230–
233 silently or in pairs. As the students
come across the vocabulary terms from
the cards they are encouraged to reorganize the cards based on their deeper
understanding of the vocabulary and
context. (15 minutes).
Upon completion of the reading, students
will copy their final concept map into
their notebooks and add arrows to show
the connections among the terms.
Students who finish quickly may be
challenged to explain why they made the
connection on each of the arrows. (10
minutes)
*Modification: Students who have
difficulty with reading the text may grasp
the key vocabulary with a guided analysis
of the two key graphics (8.4 & 8.7). The
“Interpreting Graphics” worksheet can
help students systematically analyze a
graphic and draw conclusions.
The concept of nucleotides and base pairing
is extremely abstract. Thus far, the activities
are all aimed at helping students
conceptualize the four bases and what
geometric shapes results from their pairing.
The students are moving from actual
experience and 3D to analyzing a 2D
graphic with the same basic information.
There are multiple opportunities for
students to share their ideas and check their
answers in small groups prior to sharing out
with the class.
Re-visit Vocabulary Self-Rating and
complete the column “After Extend.”
V. Evaluate:
(5 minutes)
Ongoing formative assessment.
Throughout the lesson sequence the teacher
utilizes formative assessments to gauge the
students’ acquisition of the new content.
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