My Science Box

Getting Ready

1. Day 1 - Set up the crime scene. See Sources section for some great ideas for crimes that can be staged in a classroom and ideas for how to run a forensics unit.
2. Day 2 - Cut adding tape into 1 meter long strips. Set out scissors and meter sticks.
3. Day 3 – Tape out areas for the gels. All students can run their DNA on the same gel, or you can spread them out a little more by having groups of 5 students run their DNA on separate gels. For 5 students to run a gel, tape out a 100 inch (8.33 foot) x 60 inch (5 foot) rectangle. For all students to run their DNA on the same gel, you will need an area that is 100 inches long and wide enough for each student to have a minimum of 1 foot per person. The calculations are easiest if a single base pair DNA piece can travel 99 inches, 2 base pairs travel 98 inches, and so on. If your floor has small floor tiles, you can use those as your markers rather than inches.

Teacher Background
The crux of this activity is the creation of a DNA sequence on a strip of adding tape, replication of the DNA, then using these DNA sequences to perform DNA fingerprinting.

DNA replicationThe base pairing rules help explain the process of DNA replication – how a cell makes an exact copy each strand of DNA just before it divides. First, an enzyme called helicase unzips the DNA down the middle of the ladder, in between the base pairs. Next, an enzyme called DNA polymerase reads one half of the strand, identifies a matching nucleotide, and builds a new partner strand. The process is complicated by the fact that DNA polymerase can only work in one direction along the sugar-phosphate backbone (remember, that the 2 backbones are oriented in opposite directions to one another). Thus, while DNA polymerase can easily run continuously along one strand, known as the “leading” strand, the other “lagging strand” must be assembled in a piecemeal fashion, one section at a time.

Time
Day 1+: Investigating the crime scene (may take up to a week depending on the complexity of the evidence)
Day 2: Creating DNA samples and replicating DNA
Day 3: Running the “gel” and analyzing DNA fingerprint results

Grouping
Crime scene may be studied in teams or as a whole class. DNA samples are created and replicated individually. The gel is run and analyzed as a whole class.

DNA adding tapeIn this CSI activity, students solve a mystery using “DNA” taken from the scene of the crime. This write up describes how to collect a “DNA sample” (student ...

Sources
The inspiration for this assessment activity is the book The Cartoon Guide to Genetics by Larry Gonick and Mark Wheelis. It’s a wonderful textbook alternative that teaches genetics in a very entertaining, humorous way.

Standards
Grade 7
Genetics

Lesson Plan

1. Review the idea of transcription and translation. As you do, write down key concepts (see table below) in a column on the side of the board.

   Protein synthesis key concepts: DNA is located in the nucleus of the cell. The sequence of DNA nucleotides forms the genetic code. RNA polymerase separates the 2 strands of DNA and then matches an RNA nucleotide to each DNA nucleotide. This chain of RNA nucleotides forms a molecule of messenger RNA. The messenger RNA leaves the nucleus. A ribosome assembles around the messenger RNA The ribosome reads the sequence of codons in the messenger RNA and matches a transfer RNA molecule to each codon. The ribosome assembles the amino acids brought by the transfer RNA into a chain. The finished chain of amino acids is a protein.

Teacher Background
See background information from Protein Factory lesson.

Student Prerequisites
Good understanding of DNA structure (see DNA Models lesson) and protein synthesis (see Protein Factory lesson).

Getting Ready

Time
30 min to introduce the activity. 1-3 hours to complete and present the comic strips.

Grouping
Individual

Materials

• White copy paper
• Colored pencils
• Optional: handouts or overhead specifying the concepts that must be included

Setting
Classroom

Protein synthesis comic strip Created by teachers from the Science STARTS/Delta Sierra Science Program summer institute Let your creative juices flow. The process of translating nucleic acids into amino acids ...

Sources
This activity was put together from the bright ideas of several great teachers: Lori Lambertson of the Exploratorium Teacher Institute and Jim Youngblom of CSU Stanislaus.

Standards
Grade 8
Chemistry of Living Systems (Life Sciences)
6. Principles of chemistry underlie the functioning of biological systems. As a basis for understanding this concept:
c.     Students know that living organisms have many different kinds of molecules, including small ones, such as water and salt, and very large ones, such as carbohydrates, fats, proteins, and DNA.

Grade 9-12
Genetics
4.   Genes are a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism. As a basis for understanding this concept:
a.     Students know the general pathway by which ribosomes synthesize proteins, using tRNAs to translate genetic information in mRNA.
b.     Students know how to apply the genetic coding rules to predict the sequence of amino acids from a sequence of codons in RNA.
e.     Students know proteins can differ from one another in the number and sequence of amino acids.