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Unit VI Structure and Function of DNARNA Teaching Module B-4

By Randy Black,2014-11-26 12:45
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Unit VI Structure and Function of DNARNA Teaching Module B-4

    Unit VI Structure and Function of DNA/RNA Teaching Module B-4.1

Instructional Focus

    Compare DNA and RNA in terms of structure, nucleotides, and base pairs.

Content Overview for Module B-4.1

There are two types of nucleic acids.

    ? Deoxyribonucleic acid (DNA)

    ? Ribonucleic acid (RNA)

Both DNA and RNA are composed of small units called nucleotides. The

    nucleotides that compose nucleic acids have three parts:

    ? A nitrogenous base

     Cytosine (C)

     Guanine (G)

     Adenine (A)

     Thymine (T) (DNA only)

     Uracil (U) (RNA only)

    ? A simple (pentose) sugar

     Deoxyribose (DNA only)

     Ribose (RNA only)

    ? A phosphate group

The basic structure of the two molecules is different.

     DNA consists of two single chains which spiral around an imaginary axis to form

    a double helix with nitrogenous bases from each strand of DNA chemically

    bonded through the axis of the helix.

    ? When the nitrogenous bases of two strands of DNA chemically bond through

    the center of the helix, each base can bond to only one type of base. Bases

    that bond are called complementary bases.

     Guanine (G) and Cytosine (C) will only bond with each other.

     Thymine (T) and Adenine (A) will only bond with each other.

    1 Unit VI Structure and Function of DNA/RNA 3 7-1-10 S Curriculum

Content Overview for Module B-4.1

     RNA consists of a single chain of nucleotides with nitrogenous bases exposed

    along the side.

    ? When the nitrogenous bases of RNA chemically bond to a strand of DNA,

    each RNA base can bond with only one type of DNA base. Bases that bond

    are called complementary bases.

     Guanine (G) and Cytosine (C) will only bond with each other.

     Thymine (T) and Adenine (A) will only bond with each other. It is

    essential for students to compare the structure of the two types of

    nucleic acids.

     DNA RNA

    Cytosine (C) Cytosine(C) Type of base composing Adenine (A) Adenine (A) nucleotides Guanine (G) Guanine (G) Thymine(T) Uracil (U) Type of sugar composing deoxyribose ribose nucleotides

     Molecule structure and shape Double helix Single chain

Instructional Progression

Previous and future knowledge

This concept has not been addressed in previous grades.

Instructional Considerations

It is essential for students to understand that nucleic acids are organic

    molecules that serve as the blueprint for proteins and, through the action of proteins, for all cellular activity.

It is not essential for students to understand

     the chemical formula for DNA or RNA;

     the difference between pyrimidine bases and purine bases.

Key Vocabulary and Concepts

    Nucleic acids: deoxyribonucleic acid (DNA), ribonucleic acid (RNA) Nucleotides: nitrogenous base, sugar, phosphate group Complementary bases

    2 Unit VI Structure and Function of DNA/RNA 3 7-1-10 S Curriculum

Materials Needed

See Instructional Planning Guide Activity and Appendix I.

Suggested Teaching Module B-4.1

Revised Taxonomy: 2.6-B Understand Conceptual Knowledge

Introduction

    This module can be introduced by discussing the structural make up of DNA and RNA. It is important to explain the difference between DNA and RNA. RNA consists of a single chain of nucleotides, ribose and it is single stranded whereas DNA is double stranded and has deoxyribose as a sugar. There are four nitrogenous bases in DNA Adenine, Thymine, Guanine and Cytosine. RNA also consists of four nitrogenous bases Adenine, Uracil, Guanine and Cytosine. Uracil replaces Thymine in RNA. It is important for students to be able to pair nitrogenous bases with complimentary structures. A recommended website entitled “Compare DNA and RNA in Structural Basis (http://www.dnatube.com/video/1017/Compare-DNA-

    and-RNA-in-structural-basis), as well as, “DNA Structure”

    (http://www.sumanasinc.com/webcontent/animations/content/DNA_structure.html)

    can serve as a foundation animating the structure of DNA. This can be followed by using Building RNA and DNA (Instructional Planning Activity Guide B-4.1a, p12 ). After using this activity, the students should complete Comparing DNA and RNA (Instructional Planning Activity B-4.1b, p 15) and/or the follow-up questions found in DNA-RNA (Instructional Planning Activity Guide B-4.1c. p 17). Modeling DNA (http://www.kidsknowit.com/interactive-educational-movies/free-online-movies.php?movie=DNA is a website that can be used to bring closure to module B-4.1. It is important that the students are able to recognize, differentiate and interpret a DNA and RNA nucleotide.

Suggested Resources

See Instructional Planning Guide Activity and Appendix I.

    3 Unit VI Structure and Function of DNA/RNA 3 7-1-10 S Curriculum

Assessing Module B-4.1

Formative and Summative assessments

    The objective of this indicator is to compare DNA and RNA in terms of structure, nucleotides and base pairs; therefore, the primary focus of assessment should be to detect simi