Today, we will review the concepts of translation and see why it is so important that proteins have been translated correctly.
1. Each student will have an activity sheet, prompting them to make a sandwich.
2. They have all the tools to make a peanut butter and jelly sandwich, but their directions cause all but one of them to make the wrong sandwich.
3. After the activity, the students will gather their sandwiches to take to a peanut butter & jelly picnic.
4. Each student will show which sandwich they brought to the picnic.
5. Can we have a peanut butter & jelly picnic? Why or why not?
6. In terms of translation of RNA into proteins, does this pose a problem? [Yes] How? [mutations]
Procedure:
1. Begin teacher-led discussion, reviewing translation (see above Set):
i. Amino acids are assembled from information encoded in mRNA. As each codon on t
the mRNA is paired with the anticodon on the tRNA, an amino acid is added to the
polypeptide chain.
ii. What are proteins made of? amino acids. So, those amino acids we’re forming during
translation creates the proteins. Once that protein is “activated” or turned on, gene
expression occurs.
2. Activity: Peanut Butter & Jelly Picnic (see above Set).
3. Being teacher led discussion on the different types of mutations: [Page 224]
i. Germ-cell mutations: Occurs in the germ cells (gametes). Does not affect organism
but can be passed to offspring, if gamete is fertilized.
ii. Somatic: Occurs in body cells; can affect organism, but aren’t passed to offspring
(Ex: leukemia, skin cancer, etc.)
4. Chromosome Mutations: Either changes structure of chromosome or loss of chromosome
(Page 225)
i. Deletion: Loss of a piece of chromosome due to chromosomal breakage.
a. Why is this so detrimental? All information on the missing piece is lost.
ii. Inversion: Segment breaks off, rearranges/ turns, and reattaches to the same
chromosome.
iii. Translocation: A segment of the chromosome breaks off and reattaches to another,
non-homologous chromosome.
5. Point Mutations: Substitution, insertion, or deletion of a single nucleotide.
i. Substitution- One nucleotide in a codon is replaced with a different nucleotide.
a. Sickle-cell anemia: Caused when adenine is substituted with thymine in a single DNA
codon. Makes a defective hemoglobin protein, which causes red blood cells to become
“sickle” shaped.
b. Occurs in approximately 1 out of every 500 African Americans.
ii. Insertion- One or more nucleotides are added in a gene.
iii. Deletion- One or more nucleotides are deleted in a gene.
Insertions and deletions create a frame shift mutation: Occurs when an insertion or deletion is not in multiples of three. Why? Because a codon consists of three nucleotides, read to create one amino acid.
6. Activity: Line “sandwiches” back up at front of classroom and have them perform the point mutations.
7. Closure
(20 minutes)
Closure:
Mutations can occur in gametic and skin cells. What are the three chromosomal mutations that can occur? Deletion, inversion & translocation. Definitions? There are also point mutations that can occur, which involve the substitution, insertion, or deletion of one or more nucleotides. Why is it important that no mutations/ or few mutations occur? [To have correct gene expression] Tomorrow, we’re going to continue or discussion on mutations and look at more situations where mutations have affected the expression of a particular gene. Class dismissed!
(5 minutes)
Assessment/ Evaluation:
Objective(s):
Identify the effects of various mutations on gene expression (DOK 1 Biology, 5.b).
Informal: The teacher will listen to the students' responses (M) when identifying the
types of mutations they create during the activity (C).
Formal: The student will turn in a quiz on the different types of mutations (C), and their
grades will be recorded in the grade book (D).
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