TRANSCRIPTION

BELLWORKOBJ: SIMULATE THE PROCESS OF TRANSCRIPTIONHW: FINISH TRANSCRIPTION PROBLEMS

1. What is the “central dogma or big idea” of biology?

2. What are the 3 kinds of RNA?

3. Describe the function of each type of RNA

4. Give at least 2 reasons why making proteins is such an important process

5. When you are finished, write down as many things as you can remember about the similarities & differences between DNA & RNA

VIDEO CLIP: CHEFS

http://www.youtube.com/watch?v=H5udFjWDM3E

SO HOW DOES RNA MAKE PROTEINS???

DNA

RNA

Protein

DNA stores information to run cell

Proteins actually DO the work in the cell

RNA’s function

is to make

proteins!

PROTEIN SYNTHESIS

To get from a DNA gene to a protein, the cell has to perform protein synthesis.

It requires 3 types of RNA: mRNA rRNA tRNA

It happens in 2 parts: Transcription Translation

TRANSCRIPTION

Transcription is the process of making an mRNA copy of the DNA instructions (recipe for a protein). Occurs in the nucleus.

TRANSCRIPTION VIDEO CLIP

http://www.dnalc.org/resources/3d/TranscriptionBasic_withFX.html

TRANSCRIPTION- STEP1 SIGNAL

Transcription begins when the cell receives a message to make a certain quantity of a specific protein.

EXAMPLE

After drinking milk, your cells receive a signal to begin making more LACTASE- the enzyme that breaks down lactose (milk sugar)

What other example can you think of that would

signal cells to make a protein?

RNA Polymerase “unzips” the DNA so it can get to the gene (recipe for the protein) on a single strand

TRANSCRIPTION- STEP 2 UNZIPPING

What kind of molecule is RNA polymerase (hint- look at the ending of the word)?

RNA polymerase binds to the promoter or starter DNA sequence (usually “TATA”) and begins making the complementary mRNA copy

TRANSCRIPTION- STEP 3 BINDING & READING

PRACTICE

Try #1 on your transcription worksheetG C C T G A C A C G T C A T C C C G A G T A A A

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ #2- Circle promoter (TATA) GACCTATAGTCTAG CTATAATGCTACACTGAGCTGCG

CAGGATATCAGATC GATATTACGATGTGACTCGACGC

 

GTCGAACGTATACGGGTGCATGATCCT GTATCGATCGAAATATCGATCGTTA

CAGCTTGCATATGCCCACGTACTAGGA CATAGCTAGCTTTATAGCTAGCAAT

#3- Underline the sequence that will be copied into mRNA

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

PRACTICECircle the promoter, underline the sequence to be made into

mRNA, make the complementary mRNA underneath

T G C A T A T G G G A T G T G C T G A T C G A T T G A G T G A A C G T A T A C C C T A C A C G A C T A G C T A A C T C A C T

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

After gene is transcribed, DNA zips back up (closes)

TRANSCRIPTION- STEP 4 DNA CLOSES

TAKE YOUR HANDOUT

Fold it correctly to reveal the hidden picture!

mRNA is spliced Segments called introns are removed (not part

of the recipe) Segments called exons are kept (final recipe)

TRANSCRIPTION- STEP 5 MRNA SPLICING

TALK TO YOUR NEIGHBOR

How did the Harry Potter fold-in model the process of mRNA splicing? Explain introns vs exons.

BELLWORK

1. Explain the analogy of the cake making.

What is the Recipe book?What is the copy of the recipe?What is the recipe?What is the ‘name’ of the recipe that

alerts you to it’s presenceWhat is the cook who ‘reads’ the

recipe?What are the ingredients called?

PRACTICECircle the promoter, underline the sequence to be made into

mRNA, make the complementary mRNA underneath

T G C A T A T G G G A T G T G C T G A T C G A T T G A G T G A A C G T A T A C C C T A C A C G A C T A G C T A A C T C A C T

mRNA: G G G A U G U G C T G A U C G A U U G A G U G A

Boxed-in parts = introns

Remove introns: G G G A U G U G C T G A A U U U G A

Mature mRNA: G G G A U G U G C T G A A U U U G A

The mature mRNA leaves the nucleus to find a ribosome

TRANSCRIPTION- STEP 6 MRNA LEAVES NUCLEUS

TRANSCRIPTION SUMMARY- SUMMARIZE TRANSCRIPTION TO YOUR NEIGHBOR

TRANSCRIPTION ACTIVITY

1. You and your partner will receive a “signal” in the cytoplasm (lab table) to begin transcription of a specific protein

2. Go into the nucleus (desk-side) & find the appropriate gene on the DNA molecule to transcribe mRNA from

3. Record the mRNA on your worksheet

4. Splice the mRNA according to instructions

5. Take your mature mRNA out of the nucleus & into the cytoplasm to (double check it with the answer key at your lab table)

6. Move to the next lab table to get a new signal & repeat

**If you finish early, begin the HW problems

CLOSURE

Write a note to a student who was absent explaining what they need to know about transcription.

**If you finish early, begin the HW problems