(Solved) Identify bases in the bottom strand that can be transcribed into start and stop

kdol

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9 years ago Edited: 9 years ago, duddy

Identify bases in the bottom strand that can be transcribed into start and stop

Recall that DNA and RNA are synthesized only in the 5'→3' direction and that DNA and RNA sequences are written in the 5'→3' direction, unless otherwise noted.

Consider the following DNA sequence:
5' TTGAAATGCCCGTTTGGAGATCGGGTTAC AGCTAGTCAAAG 3'
3' AACTTTACGGGCAAACCTCTAGCCCAATG TCGATCAGTTTC 5'

Identify bases in the bottom strand that can be transcribed into start and stop codons. Write the mRNA sequence (in the form of triplets, for example, GGG-AAA-CCC) that would be transcribed between start and stop codons if the bottom strand served as the template for RNA polymerase.

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duddy

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Staff Member

9 years ago

Quote from: kdol (9 years ago)

3' AACTTTACGGGCAAACCTC TAGCCCAATGTCGATCAGT TTC 5'

First, convert this to mRNA.

A's become U
T's become A
C's become G
G's become C

Then look for either AUG (start)

...and

For the stoppers.

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kdol Author

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9 years ago

I tried that and got CCC-GUU-UGG-AGA-UCG-GGU-UAC-AGU which was incorrect.

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bio_man

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Educator

9 years ago

3' AACTTTACGGGCAAACCTC TAGCCCAATGTCGATCAGT TTC 5'
Downwards Arrow

5' UUG ...

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kdole

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9 years ago

^ We have to start at the start codon so you wouldn't include the "AAC"

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bio_man

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Educator

9 years ago

3' AACTTTACGGGCAAACCTCTAGCCCAATG TCGATCAGTTTC 5'
Downwards Arrow

5'- AAC UUU ACG GGC AAA CCU CUA GCC CAA UGU CGA UCA GUU UC -3'

Interesting, no AUG Undecided

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ortho2122

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9 years ago Edited: 9 years ago, ortho2122

Just because the polymerase is going to transcribe off the bottom strand doesn't mean you have to search for the start codon by looking at the bottom strand. Look for a proper start codon in the upper strand sequence and see if you can read anything else in frame with it. I see one start codon that is in frame with a 9-residue peptide before hitting a stop codon.

Post Merge: 9 years ago

Except that the last codon should be AGC instead of AGU, and I would have included the AUG start codon, I don't see anything wrong with your answer, kdole.

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kdol Author

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9 years ago

The correct answer was

AUG-CCC-GUU-UGG-AGA-UCG-GGU-UAC-AGC-UAG

Thanks everyone!

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sarahishere13, Jc72, klig123, attaus

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bio_man

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Educator

9 years ago

Thanks for the update, kdol.

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Answer verified by a subject expert

Secret C.

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8 years ago Edited: 8 years ago, Secret Combo

Source I got both questions wrong but the automated HW gave me the right answers back. Enjoy

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Identify bases in the bottom strand that can be transcribed into start and stop

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