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DNA transcription

DNA transcription is the process by which the cell makes an RNA copy of the DNA original.

Essential questions: Why does the cell do this? How does the cell do this?


DNA, deoxyribonucleic acid

the original, kept safe in the nucleus.

mRNA, messenger ribonucleic acid

the copy, which will leave the nucleus & go into the cytoplasm

Transcription and Translation

How does the cell do this?

1. In the nucleus, the DNA gene unzips

DNA unzips

from mtel.nesinc.com, Biology Sample Open-Response Item

2. mRNA nucleotides  (C, G, A and U)  float in.

3. They join up with their complimentary DNA



4. Completed mRNA molecules now peel off, and moves away.


Why does the cell do this?

Consider the DNA to be like an original blueprint. Very important, and we want it protected. We also might use it more than once.

Consider mRNA to be like a photocopy. We can make as many as we need. And if the copy gets damaged, that’s Ok because we still have the original.

DNA RNA blueprint analogy copier

What is the difference between DNA and RNA?

RNA has sugar as part of its backbone, with some oxygen atoms.

DNA has a different sugar as part of its backbone, with 1 less oxygen atom. (that’s why it’s called deoxy)

ribose deoxyribose sugars

DNA comes in four shapes: C, G, A and T

Thymine (T) is only found in DNA

RNA comes in four shapes: C, G A and U.

Uracil (U) is only found in RNA

DNA is double-helical, while RNA is single helical.




Video: Transcription & Translation, DNA Learning Center


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