1. Remember . . . . . . DNA = genetic information
DNA replication = unzipping of double helix and creating a new strand of DNA!

2. Picture this
You are a cell!! You want to make a protein, what do you do??? You have to get DNA  RNA  protein Protein synthesis!!

3. 8. 4 KEY CONCEPT Transcription converts a gene into a
8.4 KEY CONCEPT Transcription converts a gene into a single-stranded RNA molecule.
RNA carries DNA’s instructions.
Central dogma = info. flows in direction, from DNA to RNA to protein!

4. It includes 3 processes: Replication Transcription Translation RNA =
Ribonucleic acid
RNA = link btw
DNA & proteins!
replication
transcription
translation

5. Oh Man!!! DNA can’t leave the nucleus!!!
Which organelle makes proteins????
RIBOSOMES!
DNA’s code must be carried from the nucleus to the cytoplasm!!!
RNA does the job!

6. Let’s compare DNA & RNA!! Deoxyribose sugar Ribose sugar A, C, T, G
Double stranded
Ribose sugar
A, C, Uracil, G
Single stranded

7. Transcription
Process by which a portion of DNA (a “gene”) is copied into a complementary strand of RNA.
The DNA code is transferred out of the nucleus  ribosomes

8. RNA pol. reads template & makes complimentary strand!!
RNA polymerase recognizes start site of gene & UNWINDS DNA!!
RNA polymerase
New RNA strand
RNA strand hangs free & detaches once transcribed!!!
Nucleotides
DNA molecule

9. Transcription is catalyzed (started) by RNA polymerase.
RNA polymerase and other proteins form a transcription complex.
The transcription complex recognizes the start of a gene and unwinds a segment of it.
start site
nucleotides
transcription complex

10. RNA polymerase moves along the DNA
Nucleotides pair with one strand of the DNA.
RNA polymerase bonds nucleotides together.
DNA helix winds again as the gene is transcribed.
DNA
RNA polymerase moves along the DNA

11. The RNA strand detaches from the DNA once the gene is transcribed.

12. Transcription makes 3 types of RNA:
carries the message that will be translated to form a protein.
forms part of ribosomes (where proteins are made)
takes amino acids from the cytoplasm to a ribosome.
Ribosomal RNA (rRNA)
Transfer RNA (tRNA)

13. The transcription process is similar to replication....HOW??
Transcription & replication both involve
complex enzymes &
complementary base pairing.
BUT...have different end results:
Replication copies all the DNA; transcription copies a gene.
Replication makes one copy; transcription can make many copies.
growing RNA strands
DNA
one
gene