Purpose and Procedure:
The purpose of this lesson is to introduce the students to the basic structure of the DNA
molecule. Have the students read the section in their textbook regarding the basic
structure of DNA. Open the attached webpage, titled “Basic DNA Structure” and present
it to the class. After presenting it to the class, have the students take out a piece of paper
and answer the quiz questions attached to this page. Open and review the webpage while
correcting the quiz, to reinforce the basic DNA structure.
7th Grade Life Science Standards:
Genetics:
2. A typical cell of any organism contains genetic instructions that specify its
traits.
Those traits may be modified by environmental influences. As a basis for
understanding this concept:
e. Students know DNA (deoxyribonucleic acid) is the genetic material of
living organisms and is located in the chromosomes of each cell.
.
Investigation and Experimentation:
7. Scientific progress is made by asking meaningful questions and conducting
careful investigations. As a basis for understanding this concept and addressing
the content in the other three strands, students should develop their own questions
and perform investigations. Students will:
a. Select and use appropriate tools and technology (including calculators,
computers, balances, spring scales, microscopes, and binoculars) to
perform tests, collect data, and display data.
d. Construct scale models, maps, and appropriately labeled diagrams to
communicate scientific knowledge (e.g., motion of Earth's plates and cell
structure).
Objectives:
The students will:
1. Understand that the heredity code that genes contain is called DNA
(deoxyribonucleic acid).
2. Understand that the DNA structure is a double-helix or twisted ladder shape.
3. Understand the structure of the DNA molecule includes the sugar-phosphate
backbone and four nitrogenous bases; adenine, thymine, cytosine, and guanine.
4. Understand that adenine always pairs with thymine and cytosine always pairs
with guanine.
Assessment:
After viewing the introductory DNA lesson, the students knowledge will be assessed
through the following Quiz:
1.
2.
3.
4.
5.
6.
DNA stands for ____________________________________ ____________.
The __________-____________ backbone connects the four bases.
The four nitrogenous bases are_______, _____, _______, _______.
___________ always pairs with _______________.
___________ always pairs with _______________.
Draw a diagram showing the DNA structure with the correctly paired bases.
Key:
1.
2.
3.
4.
5.
6.
DNA stands for deoxyribonucleic acid.
The sugar-phosphate backbone connects the four bases.
The four nitrogenous bases are adenine, thymine, cytosine, and guanine.
Adenine always pairs with thymine.
Cytosine always pairs with guanine.
See DNA webpage.