Alien Encounters!

Guiding Question: What is the relationship between DNA, mRNA, proteins, and actual traits?

Background: In the year 2050, an incredible archeological discovery was made in the middle of a remote area of South America. It was an area where a large meteor had struck the Earth. A pile of alien bones was found completely mixed up together. The explorers who made the discovery immediately informed the organization known as Scientific Phenomena Over Our Fabulous Sphere (S. P. O. O. F. S). S. P. O. O. F. S. sent out its best scientists to collect DNA samples. (Yes, these aliens really did have DNA!) The scientists were able to recover small fragments of DNA which they brought back to their labs. After much work, they determined that the DNA fragments represented 9 genes.

Purpose: In this activity, you will determine the traits of these unfortunate recovered aliens by analyzing their DNA and determining the amino acid sequences of the resulting small protein fragments. Each fragment is associated with a particular gene and a specific alien characteristic (trait).

Procedure:1. Your teacher will give you a unique DNA sequence. 2. Put the DNA sequence for each gene in the proper location on your data sheet

(page 3).3. Transcribe the DNA for each gene into mRNA. Record these sequences on the

line that reads mRNA on your data sheet4. Translate the mRNA into amino acids using the provided mRNA Codon Chart

(top of page 2) Record the amino acid sequence for each gene at the indicated location on your data sheet.

5. Use the “Alien Genes” chart (bottom of page 2) to determine the traits that are associated with each of your amino acids sequences and write those traits on the data sheet in the indicated location.

6. Complete the Analysis Questions on page 4.

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mRNA CODON CHART

ALIEN GENES

This table shows the amino acid sequences for the various alien genes and traits.

Gene Letter

Amino Acid Sequence Resulting Characteristic

A Val-pro-ileu HairlessTryp-pro-ileu Hairy

B Tryp-val-val fat Ileu-ileu-ser skinny

C Ser-ala 4 legsSer-ser 8 legs

D Pro-ser-phe-gly Long noseGln-ser-phe-gly Short nose

E Lys-phe No antennae

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Lys-leu 4 antennaeF Pro-ala-ala Blue skin

Pro-ala-asp Red skinPro-ala-val Yellow skinPro-ala-pro Green skin

G Gln-gln-asp 10 fingersGln-gln-lys 12 fingers

H Gly-gly-ileu tailala-gly-ileu No tail

I Ileu-asp-ala 4 eyesSer-asp-ala 8 eyes

Data Sheet for Alien Gene Analysis

NAME Sydney Holt Alien Number Assigned to you by your teacher #18

Is your alien hairless or hairy? Is your alien fat or skinny? GENE A GENE BDNA A C C G G T T A T DNA A C C C A A C A A mRNA U G G C C A A T A mRNA U G G G U U G U UAmino Acids Trp; Pro; Ileu Amino Acids Trp; Val; ValTrait Hairy Trait Fat

Does your alien have 4 legs or 8 legs? What size nose does your alien have? GENE C GENE DDNA A G C C G A DNA G T C A G G A A A C C C

mRNA U C G G C U mRNA C A G U C C UUUGGGAmino Acids Ser; Ala Amino Acids Gln; Ser; Phe; GlyTrait 4 legs Trait Short nose

Does your alien have antennae or not? What color skin does your alien have? GENE E GENE FDNA T T T A A A DNA G G A C G C C T A

mRNA A A A, U U U mRNA C C U, G C G, G A UAmino Acids Lys, Phe Amino Acids Pro, Ala; AspTrait No antennae Trait Red skin

How many fingers does your alien have? Does your alien have a tail? GENE G GENE HDNA G T C G T C C T A DNA C C C C C C T A T

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mRNA C A G, C A G, G A U mRNA GGG; GGG; AUAAmino Acids Gln, Gln, Asp Amino Acids Gly, Gly, IleuTrait 10 fingers Trait Tail

Does your alien have 4 eyes or 8 eyes? GENE IDNA A G C C T A C G CmRNA U C G, G A U, G C GAmino Acids Ser; Asp; Ala` 8 eyes

ANALYSIS QUESTIONS

1. Draw a picture of your alien, making sure to include all relevant (known) traits. You may do this in a drawing program on your computer, or do it on a blank sheet of paper by hand. If done electronically, try to copy/paste it here. If you draw it by hand you may scan it or take a picture with a phone and email or text it to me. I am fine with receiving your picture in any form that you can send it! Be sure to include your alien’s genus and species at the top of your drawing and data sheet.

2. Give the tRNA sequences for Gene D.C A G T C C T T T G G G

3. How does a single change in a nitrogen base alter the formation of a resulting protein?

Each sequence of bases is specific to a certain amino acid, so if one base is changed, it alters the entire acid.

4. If you knew a particular amino acid sequence, could you figure out the DNA for that sequence? Why or why not?Not if there was more than one sequence. You could narrow the DNA’s down to a few but it would be hard to guess which bases would go together after that.

5. What is the difference between transcription and translation?Transcription describes the process of mRNA being replicated from DNA.Translation requires tRNA and rRNA and transcription produces mRNA.

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6. What are the roles of the DNA, mRNA, and tRNA in protein synthesis?

DNA stores genetic information, mRNA transcribes the DNA’s information, tRNA uses the information and brings amino acids together.

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