1. Transcription: DNA  mRNA

2. Remember… DNA is the genetic code and is found in the nucleus.
The genetic code is used to make proteins, which you are made of.
But…proteins are made on the ribosomes.

3. Remember…
nucleus
DNA

4. So how does the code get from the nucleus to the ribosomes?
RNA

5. Structure of RNA RNA differs from DNA in 3 ways:
RNA is a single strand.
RNA has the sugar ribose.
RNA has the nitrogen base uracil instead of thymine.

6. Structure of RNA
Single
strand

7. 3 Types of RNA Messenger RNA (mRNA) Ribosomal RNA (rRNA)
Transfer RNA (tRNA)

8. mRNA
mRNA delivers the instructions for making a protein from the nucleus to a ribosome in the cytoplasm.

9. Transcription DNA cannot leave the nucleus.
However, its code can be copied by mRNA and taken out of the nucleus.

10. Transcription
First, the enzyme RNA polymerase binds to DNA and separates the DNA strands.

11. Transcription
Then, a strand of mRNA is transcribed (copied) using one DNA strand as a template.

12. Transcription
To copy the code, RNA nucleotides are added using the base pairing rules for DNA, except that in RNA, uracil pairs with adenine.
(G – C, A – U)

14. Practice Transcribing
Let’s practice transcribing a strand of DNA:
DNA: G T C A G A T A C
mRNA:________________ C A G U C U A U G

15. Transcription Animation

16. RNA Processing
The sequences that code for proteins are called exons because they are “expressed” in the synthesis of proteins.
The introns do not code for proteins and are cut out of the mRNA sequence before it leaves the nucleus.
The remaining exons are spliced together.

18. After Transcription
The single strand of mRNA leaves the nucleus and enters the cytoplasm.
It will then travel to a ribosome where its code will be translated into a protein.

19. After Transcription

20. Transcription & Translation
In the nucleus
In the cytoplasm (ribosome)