Robin L. Lewis

Biology I- Genetics (Day 2)

Period: 2^nd

Approximate Time: 50 minutes

Objective(s):

The Student Will...

1.       Compare and contrast the structure of RNA and DNA.  (MSF Biology I 5a)

2.      Summarize the process of transcription and translation.  (MSF Biology I 5a)

Materials:

Textbook, dry erase markers, erasers, colored paper clips, pens, pencils

Set:

Yesterday we discussed the structure of DNA and DNA replication.  DNA is important because it stores our genetic information.   DNA is special because it houses the information in a code.  The code is located in each one of your cells and it is important for your body to follow these special instructions, if not, your foot can grow out of your ear! Number the alphabet to determine the real message of the code.  Here A=1, B=2, etc.  Code: 20 15 4 1    23 5’12 12   19 20 21 4   7 5 14 5 20 9 3 19! (Today we’ll study genetics!)  The code that you just solved is like a code that would be found in DNA.  The code has to be broken down and read in order to understand its’ meaning.  RNA is the molecule that reads the code from DNA.  Today we will compare and contrast the structures of RNA and DNA, and summarize the process of transcription and translation.

Procedures:

1.      Return Summary paper from the previous day.

2.      Write the set code on the board with instructions.  Once a student has solved the puzzle correctly have him to put the answer on the board.   Continue with set.

3.      Draw the structure of RNA and DNA on the board.  Have the students examine the pictures from the board.  Next, explain what the purpose of a Venn diagram.  Draw an example of one on the board and have the students copy it onto their own paper.  Have the students complete their Venn diagram by exploring the similarities, differences, and the common features of both molecules.

4.      Examine the results from the Venn diagram.

a.      DNA: double stranded, deoxyribose sugar, thymine nitrogen base, longer

b.      RNA: single stranded, ribose sugar, uracil nitrogen base, shorter

c.       Together: both have at least one strand, a sugar, a nitrogen base, both are nucleic acids

5.      Give the students the three types of RNA.  RNA comes in three forms.  They are:

a.      mRNA (messenger RNA)-records info from DNA.  Carries message DNA to the cytoplasm

b.      tRNA (transfer RNA)- transfers amino acids to the ribosomes

c.       rRna (ribosomal RNA)-makes up ribosomes where protein synthesis takes place.

6.      Explain transcription.  Remember earlier when you had to crack the code from DNA?  In the cell RNA is responsible to read the code that DNA gives it.  Transcription- Info is copied from DNA to RNA.  Word transcription means “to write”.  DNA writes a message fro RNA to read.

a.      During DNA replication, an RNA enzyme attaches to a promoter (beginning) site.  mRNA nucleotides match up with DNA nucleotides.  G-C, but A-U

b.      Once mRNA reads the message it carries it to the cytosol.

c.       Every three nucleotides on mRNA is a codon.  Codons represent a specific amino acid.

7.      Give the students an example of transcription.  DNA strand: ATAGCATCG  How should the complementary RNA strand read? (UAUCGUAGC)  Give students more practice with this concept.

8.      Explain translation.  Now we have all of this free mRNA that RNA has read the code from DNA, it must translate the message into amino acids.  Question: Amino acids are the building blocks of what organic molecule? (proteins)  The function of all the different types of RNA is to make proteins.  The process of making proteins is called protein synthesis.

a.      tRNA carries amino acids that are floating freely in the cytoplasm to the ribosomes.  tRNA has a special part of its structure made up of three nucleotides that is called an anticodon.  Have students speculate what is an anticodon by breaking down the word.

b.      tRNA pairs with a mRNA codon.  Then the amino acids are linked by peptide bonds.

9.      Give the students an example of translation.  Let’s revisit the previous example.  Give the tRNA binding sequence for this mRNA sequence of codons is UAU CGU AGC.  (AUA GCA UCG). 

10.  Time permitting, give students Modeling Protein Assembly Quick Lab p.196 as an assignment

a.      Review procedures with the students.

b.      Have students write their analysis on a separate sheet of paper to be turned in to the teacher.

11.  Collect Quick Lab.

12.  Have students summarize the process of transcription and translation on a sheet of paper.

13.  Collect summarization papers from closure.

Closure:

Have students compare RNA and DNA, and then have them contrast RNA and DNA.  Have student volunteers to summarize transcription and have another volunteer to summarize translation.  Encourage every student to add something to the oral review.  Today we have learned how to compare and contrast the structure of RNA and DNA and to summarize the process of transcription and translation.   Tomorrow we will discuss what happens when DNA replication goes wrong.

Assessment/Evaluation:

The teacher will conduct informal assessments through observation, listening (M) to student response from the lesson, and from reading the quick lab analysis.   Students will receive a grade for the transcription and translation summaries to determine if the students can summarize the process of transcription and translation (C).  The grade will be recorded in the grade book (D).

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