Chapter 3- Section 4 The DNA Connection/Protein Synthesis

AGENDA Mon. April 16, 2007

STUDENTS

  1. Warm up
  2. Review DNA Replication
  3. Read pp. 91-96 The DNA connection
  4. DNA connection Lecture

CALIFORNIA STATE STANDARDS

1.0, 1.a, 1.c, 2.0, 2.b, 2.c, 2.d, 2.e, 7.0, 7.c, 7.d, 7.e

OBJECTIVES

  • Explain the term genetic code
  • Describe the process by which a cell produces proteins
  • Describe different types of mutations and how they affect an organism.

TEACHER

  1. Warm up
  2. Define the following words:
  3. Messenger RNA
  4. Transfer RNA
  1. The DNA Connection Lecture
  2. Overhead transparenies

Title: The DNA Connection

Main Ideas / Notes
What are the 4 nitrogen bases found in DNA?
What is important about the order of nitrogen bases?
How many nitrogen bases code for an amino acid? /
  • “A” (adenine) joins with “T” (thymine)
  • “C” (cytosine) joins with “G” (guanine)
The order of the nitrogen bases along the DNA form a genetic code that specifies the type of amino acid to be produced.
  • Amino Acids are the building blocks of proteins. There are 20 amino acids.
3 nitrogen bases code for 1 amino acid.
  • For example, think of it as THREE letter words:
dogheryouhimcat
  • These words ALL mean something different.
  • If there was a mistake made in the sequence, the cell can produce proteins that should not appear or make any sense.

What are these nitrogen base mistakes called? / These mistakes are called
MUTATIONS. For example:
dogherrouhimcat (1 mutation)
dogherryouhimca(3 mutations)

Agenda- Tue April 17, 2007

STUDENTS

  1. Warm up
  2. Protein Synthesis lecture

AGENDA – Wed April 18, 2007 and Thurs April 19, 2007

Protein Synthesis Lesson Plan

California State Standards:
7th grade Life Science
1.0All living organisms are composed of cells, from just one to many trillions, whose details usually are visible only through the microscope.
1.c The nucleus is the repository for genetic information in plant and animal cells.
2.0A typical cell of any organism contains genetic instructions that specify its traits. Those traits may be modified by environmental influences.
2.e DNA is the genetic material of living organisms, and is located in the chromosomes of the
cell.

Learning Objectives:

  • Students should be able to explain the term genetic code.
  • Students will be able to describe the process by which a cell produces proteins.

Goals:
  • Goal for Lesson: Identify how DNA and RNA produce proteins inside the cell.
  • Goal for Unit: Understand that DNA plays many important roles within the cell, and is needed for the cell to function.
  • Goal for Subject Matter: Develop scientific ways of thinking such as asking questions, observations, and use evidence to support your findings or theory.
  • Goal for Long Term: DNA is an important element of life.

Lesson Design:
Warm-up:
As a review from our previous lecture, students will individually write down the answer to the following question: In your own words, compare and contrast DNA and RNA. You may draw a Venn Diagram if you choose, however do not forget to compare as well. Use key terms when answering.
Whole group discussion:
After five minutes, students will be allowed to list results obtained for both the similarities and differences between DNA and RNA. The teacher will write responses down in a Venn diagram on the overhead projector, as the students present them.
Lesson Questions:
Based on what we discussed previously, who can tell me how nitrogen bases along a gene serve as a genetic code? How is this gene sequence important in determining proteins?
Whole group discussion:
Students will brainstorm for a few minutes and present reasons. The teacher will display manipulatives, and gene sequences in order to promote student understanding of codons (three-letter code words that make up DNA). Students should also be able to express in their discussion, some knowledge of how these codons represent an amino acid.
Introduction to Activity:
Based on information previously discussed about protein synthesis, students should have some general knowledge about the key elements involved in the production of proteins. In order to help understand and visualize this process, students will be shown various manipulatives demonstrating protein synthesis. As these manipulatives are being shown, students will be directed to their textbooks (Prentice Hall Focus on Life Science pp. 94-95) where a diagram of protein synthesis is displayed. Students will be asked to produce a “Protein Synthesis Booklet” that represents how the messenger RNA, transfer RNA, DNA, ribosomes, nucleus, and amino acids all function together to produce proteins.
Activity:
1)Each student will work individually to produce their own protein booklet, but will be able to collaborate with peers during the activity.
2)Students will be given two strips of un-lined copy paper (one paper cut in half). They will be instructed to place one strip inside the other and fold it “hamburger style” in order to make a booklet with six pages, not including the front and back. The front of the book (page 1) will be the title page “Protein Synthesis” and their name, date, period. The back of the book (page 8) will be “THE END”
3)Students will be instructed that for pages 2-7 they must fill in each page by drawing, IN ORDER, a process of protein synthesis that occurs, and explain that process in their own words using key terminology. The teacher will instruct students that they are allowed to use the diagram in their books to help them determine the drawings. However, the teacher will also point out that there are only four drawings in the book and students must draw six. Students are encouraged to use their knowledge of protein synthesis to determine where the two additional drawings should go, and what they should look like. Students will also be informed that not all of the drawings will be the same, but that the process and explanations should all clearly explain and demonstrate the steps of protein synthesis.
4)Students are directed to color and label their diagrams, remembering that colors representing nitrogen bases and organelles must remain the same throughout their drawings.
5)Students that require a higher level reasoning skills and more in depth challenge are provided a section of the DNA with specific nitrogen bases. They will also be provided with an answer key that identifies the three-letter codons that represent each amino acid. Given this section of DNA and amino acid key, these students must identify the strand of RNA that will match up with the section of DNA given, and what amino acids will join to form the protein chain as a result. Finally, students must incorporate these additional factors into their diagrams and explanations.
Homework:
Students will individually write a one-paragraph answer explaining how a change in one nitrogen base on the DNA strand can lead to a mutation, and what could be some possible consequences or advantages of this occurring?

Protein Synthesis- the production of protein

Main ideas / Notes
Where are proteins found?
How do ribosomes and chromosomes come together to produce proteins if they are located in different parts of the cell?
Compare and Contrast RNA and DNA.
How does protein synthesis begin?
What “reads” the codes to produce proteins?
What is the function of transfer RNA?
How does protein synthesis end? / Proteins are found inside the ribosomes, which are located in the cytoplasm on the cell.
  • REMEMBER: Chromosomes are located in the nucleus of the cell.
  • RNA is a genetic messenger that carries the genetic code from the DNA inside the nucleus to the cytoplasm.
  • This type of RNA is called messenger RNA
  • Unlike DNA, RNA is only single stranded NOT double stranded.
  • Like DNA, RNA also has four nitrogen bases.
  • However, instead of the base Thymine, RNA has a base called Uracil.
  • For RNA the nitrogen bases join as followed:
  • Adenine joins with Uracil
  • Cytosine joins with Guanine
The DNA molecule “unzips” and the messenger RNA strand base pairs with the DNA strand and copies the coded messages inside the NUCLEUS of the cell. The messenger RNA strand then continues into the cytoplasm.
Once in the cytoplasm, messenger RNA attaches to a ribosome and translation begins. The ribosome reads the three letter code and
allows a transfer RNA to enter into the ribosome.
The transfer RNA carries an amino acid into the ribosome to match up the three letter code and form a protein chain.
  • The ribosome moves down the messenger RNA reading new codes and allowing
new amino acids to form the protein
chain.
Once the ribosome reads a three letter STOP code, it releases the protein chain and protein synthesis ends.