The Chemical Basis of Life > Lessons

 

Lesson 11: “Mother Nature’s Marvelous Menu 4”

 

 

    Topic: Nummy yummy nucleic acids                Grade Level: 12        Duration: 2 X 60 min.

                 (DNA & RNA)

 

Student Objectives: Students will be able to:

1.  describe the similarities and differences in the structure of DNA & RNA (3.1)

            2.  describe the processes of replication and transcription (3.2)

            3.  use processes of science: C13 formulating models

4.  expand their critical and creative thinking skills (CCT), and become independent learners (IL)

 

 

Curriculum Orientation:    Transaction and transformation

 

Instructional Method:        Model Building (Experiential Learning)

 

Materials:                             Blackboard and chalk, overhead projector, overheads 1.23-1.30 (see overhead section), extra scissors and glue/tape, “Mother Nature’s Marvelous Menu, Today’s Topic: Nucleic Acids” student worksheets (see student handout section), “DNA Replication” and “DNA Transcription” student handouts (see student handout section), and outline for unit exam                         

 

 

Review:                                  Collect the students’ completed labs from last day.  Ask the

     (5 min.)                          students to list the four groups of organic compounds.  Tell them that today they will study the last group: nucleic acids, and finish cooking with mother nature.         

 

 

Presentation (115 min.):

 

A.  Motivational Set:        Assess the students’ prior knowledge about nucleic acids

      (5 min.)                              (DNA/RNA) by asking the students to tell you what they know about these three letters: DNA or RNA.  Tell the students that in today’s class, they will gain a deeper understanding of nucleic acids: deoxyribonucleic acids and ribonucleic acids by constructing models.  In next day’s class, they will study DNA replication and transcription.

 

 

 

B.  Activities:

     (95 min.)

 

Teacher Activities

Day 1

                                                1.  Hand out one DNA/RNA worksheet to each student.

2.  Tell the students that they have all class to work on their models, but that they are due at the start of next day’s class.

3.  Instruct students to get started as it takes a fair bit of time to cut out the model pieces.

4.  As students are working, meander through the classroom.  Use this time to make anecdotal records and answer student questions.

5.  With ten minutes left in the class, invite students to start cleaning up.  Remind the students that the paper scraps should be recycled and not thrown in the garbage.

6.  Assign homework: students are to have their models completed as well as the corresponding questions from the DNA/RNA handout for the beginning of next day’s class.  This is important because the models will be used in the next lesson on replication and transcription.

                                               

Day 2

1.   Do a homework check to see which students have not completed their DNA models.  Do not collect the worksheets for marks.

2.  Review the similarities and differences in the structure of DNA and RNA using overhead 1.23: “Similarities and Differences in DNA & RNA”.  Ask that the students use the overhead to check their answer to question 15.

                                                3.  Go over the answers to the rest of the questions (1-14).

4.   Pass out the student handouts on DNA replication and transcription.           

5.  Explain DNA replication using overheads 1.24: “A nucleotide,” 1.25: “DNA double helix,” 1.26: “DNA replication,” and 1.27: “DNA replication” (diagram).  Encourage the students to replicate their models (Students will need free nucleotides to do this), or to follow along on the handout.

6.  Explain DNA transcription using overheads 1.28: “DNA transcription,” 1.29: “DNA transcription” (diagram), and 1.30: “Flow of genetic material”. 

                                                7.   Bring closure to the lesson by asking key questions.

8.  Assign homework and write the unit test outline on the blackboard.              

 

 

C.  Key Questions:               Compare and contrast DNA with RNA.

Along one strand of a double helix is the nucleotide sequence GGCATA.  What is the complementary sequence for the other DNA strand?

Outline the process of DNA replication/transcription: the   ingredients, the process, and the final product(s).       

                                                Who worked out the three-dimensional structure of DNA?

Explain the statement: “DNA replication depends on specific base pairs”.

 

D.  Homework:                     Tell the students that next day’s class will be a review period­a chance to ask questions, tie up any loose ends, study­for the following day’s unit exam.  Ask that each student have one review question prepared.    

 

Evaluation:                             Formative: During the lesson, monitor the students’ work progress and behavior using anecdotal records (Day 1) (see evaluation section), and on Day 2, do a homework check and note student responses to key questions.

Summative: At the end of the chemical basis of life unit, include some relevant questions from this lesson on the test.