Transcription:Translation POGIL- Honors

Name: _________________________________________ Date: _____________________ Period: _______ Gene Expression- Transcription & Translation Why? DNA is often referred to as a genetic blueprint. In the same way that blueprints contain the instructions for construction of a building, the DNA found inside the nuclei of cells contains the instructions for assembling a living organism. The DNA blueprint carries its instructions in the form of genes. In most cases the genes direct the production of a polypeptide, from which other more complex proteins, such as enzymes or hormones, may be constructed. So, what is the language of these instructions and how are they read and decoded by the cell organelles? This activity will focus on the decoding of genes in eukaryotic cells. Model 1- Transcription & Translation

TRANSCRIPTION

TRANSLATION

1. Consider the eukaryotic cell in Model 1. a. Where in the cell does transcription take place? b. What is synthesized, or created, from DNA during transcription? c. DNA is a double stranded molecule. How would you describe the appearance of mRNA? d. Where does mRNA travel to after transcription?

2. Consider that DNA cannot leave the nucleus of a cell. mRNA, or messenger RNA can leave the nucleus. What do you think is the purpose of mRNA?

Read This! Transcription is similar to DNA replication except that in mRNA, the base Thymine (T) is no longer used. Instead, the base Uracil (U) pairs with Adenine (A). See the example below:

DNA sequence - C G A T C mRNA sequence - G C U A G

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Name: _________________________________________ Date: _____________________ Period: _______ Model 2- Transcription (DNA to mRNA)

TAC

DNA (double stranded)

A UG

mRNA (single stranded)

3. Consider Model 2.

a. Complete the statement below to describe the base pairing rule for DNA.

InDNA,Adenine(A)alwayspairswith__________(),andCytosine(C)alwayspairswith

___________().

b. Fill in the missing bases of the double stranded DNA molecule. (see the three examples)

c. Complete the statement below to describe the base pairing rule for mRNA.

InmRNA,Adenine(A)alwayspairswith__________(),andCytosine(C)alwayspairswith

___________().

d. Fill in the missing bases of the single stranded mRNA molecule using the bottom strand of DNA as the template. (see the three examples)

This is the end of the first step of gene expression, transcription, now let's take a closer look at the second step of gene expression, translation.

4. Consider the eukaryotic cell in Model 1. a. Where in the cell does translation take place? b. What cellular structures attaches to the mRNA in order to assemble proteins?

Read This!

The second step in decoding genetic messages is translation. The sequence of bases in mRNA is a set of instructions that originated in the nucleus. When a ribosome is attached to an mRNA sequence, codons, or groups of three bases, are read by the ribosome. Each codon specifies for a particular amino acid used to create a protein.

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Name: _________________________________________ Date: _____________________ Period: _______ Model 3- Universal Codon Charts

5. Consider the two diagrams in Model 3.

a. These diagrams determine which amino acid is coded for by each codon. While their appearances differ, they will both yield the same results. For an assessment, you will be required to use the codon chart on the right. The codon chart on the left is a much simpler representation; start on the inside and work your way out. For example, the codon CAC codes for the amino acid Histidine, which we can abbreviate with as "His."

b. Complete these models by determining the missing four amino acids.

A UGGUA GC UA A CCUU

mRNA

met

Amino Acids

A UUGG CCU AU UGGUA

mRNA

Amino Acids

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Name: _________________________________________ Date: _____________________ Period: _______

Read this!

Now it is time to put everything together and see how DNA determines the traits displayed by organisms. In this activity, you will examine the DNA sequence of a fictitious organism: the Snork. Snorks were discovered on the planet DeeZoo in a distant solar system. Snorks only have one chromosome with 6 genes on it. Your job is to complete transcription and translation in order to determine the traits of the Snork. Name: ___________________________________________ Date: _______________________ Period: _______

How does DNA determine the traits of an organism? Model 4- What traits do the DNA code for? IotCFonnionctmtahohlpilmesyle,ppatsclelkaetMeintvetecoitthtdryDaet,hnleye4seoc.SZ1urnoitpowoortikidilonleinnteaexarthdmnaeimdisnbtitaeonrnaxtehntletssahlobtaerleatalDiierotdsNnsoy4Aifs.n3ttsehobemeraqdsS.ueenSedronntorcookner.dktYohesofetoeuaornwumflityiccilnolthiemntaievtoeeheudoesofttonMoraerrogietcdfasheenrorliostf4omm.t1hM:oestohoSdemneloSe4rnkw.o2.riftkoh.rS6ansgsoeirsnktaesnswcoeen. riet.dYisocuorvjeorbed

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11

22

33

4

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DDNNAA AACCCCGGGGT TTATTA T A GACGCCGCAGGAGGG G GT T TTATATCAAAACA A AGAG A CGGGCACCGGAC CGGGAG A GG GGAGAAAG GTATACAT T CTCTTCAT T C C T A

mRNA U G G C C A A U A mRNA U G G C C A A U A

Amino Acmidins o

try-pro-iso try-pro-iso

NAamcied:s___________________________________________ Date: _______________________ Period: _______

Traits

Hairless

Traits

Hairless

Model 4.1

Amino Acid Sequence try-pro-iso try-gly-iso ser-ala-pro ser-arg-pro pro-val-phe pro-ser-phe lys-phe-phe lys-leyus--pahsep pro-ala-ala pro-ala-cys llyeus--lleeuu--apshpe leu-leu-arg

Model 4.2

Trait hairless

hairy 4 legged 2 legged round head block head no tail

tail square eyes round eyes long legs short legs

SketcShkyeotuchr Synoourrk Shneroer:k here:

Model 4.3

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