TRANSCRIPTION
Feb 23, 2016
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
TRANSCRIPTIONTranscription 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/Transcripti
onBasic_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 ACTIVITY1. 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
CLOSUREWrite a note to a student who was absent
explaining what they need to know about transcription.
**If you finish early, begin the HW problems