Unraveling the Code: Exploring DNA's Molecular Structure

Biology Grades High School 13:00 Video
Print Lesson Plan Watch Video

Lesson Description

This lesson dives deep into the molecular structure of DNA, exploring its components and how they contribute to its function. We'll examine nucleotides, nitrogenous bases, and the double helix.

Video Resource

Molecular structure of DNA | Macromolecules | Biology | Khan Academy

Khan Academy

Duration: 13:00
Watch on YouTube

Key Concepts

  • Nucleotide structure (phosphate group, sugar, nitrogenous base)
  • Nitrogenous base pairing (Adenine-Thymine, Guanine-Cytosine)
  • Deoxyribose vs. Ribose
  • Purines and Pyrimidines
  • Hydrogen bonding in DNA

Learning Objectives

  • Students will be able to identify the components of a nucleotide.
  • Students will be able to explain the difference between deoxyribose and ribose.
  • Students will be able to describe the base pairing rules in DNA.
  • Students will be able to differentiate between purines and pyrimidines.
  • Students will be able to explain the role of hydrogen bonds in DNA structure.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing the basic function of DNA as the carrier of genetic information. Briefly discuss the central dogma of molecular biology (DNA -> RNA -> Protein). Pose the question: How does DNA's structure enable it to perform its function?
  • Video Viewing (15 mins)
    Play the Khan Academy video "Molecular structure of DNA | Macromolecules | Biology | Khan Academy." Instruct students to take notes on the key components of DNA structure.
  • Discussion and Clarification (15 mins)
    Lead a class discussion to clarify any points from the video that students found confusing. Focus on the following: the components of a nucleotide, the difference between deoxyribose and ribose, the names of the nitrogenous bases, the difference between purines and pyrimidines, the base pairing rules, and the role of hydrogen bonds.
  • Activity: Building a DNA Model (20 mins)
    Students will work in small groups to construct a simplified model of a short DNA sequence using provided materials (e.g., colored paper, pipe cleaners, beads). They should label each component (phosphate, sugar, base) and illustrate the correct base pairing. Alternatively, a digital model can be created using online tools.
  • Wrap-up and Assessment (5 mins)
    Review the key concepts covered in the lesson. Assign the multiple-choice and fill-in-the-blank quizzes for homework or in-class assessment.

Interactive Exercises

  • DNA Structure Jigsaw
    Divide the class into four groups. Each group becomes an expert on one of the following topics: 1) Nucleotides, 2) Sugars (ribose/deoxyribose), 3) Nitrogenous Bases (Purines/Pyrimidines), 4) Base Pairing and Hydrogen Bonds. Each group prepares a short presentation to teach the rest of the class about their assigned topic.

Discussion Questions

  • Why is it important for DNA to have a stable structure?
  • How does the structure of DNA allow it to be easily replicated?
  • How does the slight difference between ribose and deoxyribose affect their respective roles in the cell?

Skills Developed

  • Model building
  • Critical thinking
  • Scientific communication
  • Note taking

Multiple Choice Questions

Question 1:

Which of the following is NOT a component of a nucleotide?

Correct Answer: Amino acid

Question 2:

Which nitrogenous base pairs with Adenine (A) in DNA?

Correct Answer: Thymine (T)

Question 3:

What type of bond holds the two strands of DNA together?

Correct Answer: Hydrogen bond

Question 4:

Which of the following is a purine?

Correct Answer: Adenine

Question 5:

What is the difference between ribose and deoxyribose?

Correct Answer: Deoxyribose lacks an oxygen atom on the 2' carbon, ribose has one.

Question 6:

What part of the nucleotide makes DNA acidic?

Correct Answer: Phosphate group

Question 7:

Which of the following is a pyrimidine?

Correct Answer: Cytosine

Question 8:

How many rings do purines have?

Correct Answer: Two

Question 9:

Which of the following binds with Guanine?

Correct Answer: Cytosine

Question 10:

Where is DNA typically found in eukaryotes?

Correct Answer: Nucleus

Fill in the Blank Questions

Question 1:

The building blocks of DNA are called ________.

Correct Answer: nucleotides

Question 2:

The sugar found in DNA is called ________.

Correct Answer: deoxyribose

Question 3:

The nitrogenous base ________ pairs with guanine.

Correct Answer: cytosine

Question 4:

Nitrogenous bases with two rings are called ________.

Correct Answer: purines

Question 5:

The bonds that hold the nitrogenous bases together are ________ bonds.

Correct Answer: hydrogen

Question 6:

Adenine and Guanine are classified as ________.

Correct Answer: purines

Question 7:

Cytosine and Thymine are classified as ________.

Correct Answer: pyrimidines

Question 8:

Deoxyribonucleic acid is the junction for ________ acid.

Correct Answer: nucleic

Question 9:

Adenine binds with ________ in DNA.

Correct Answer: thymine

Question 10:

DNA is found in the ________ of eukaryotes.

Correct Answer: nucleus

Educational Standards

B.LS1.1:Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. B.LS3.1:Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.

Teaching Materials

Download ready-to-use materials for this lesson:

Student Worksheet Classroom Slides Assessment Quiz
Add to Google Classroom

User Actions

Sign in to save this lesson plan to your favorites.

Sign In

Share This Lesson

Related Lesson Plans