1. Transcription
Using DNA to make RNA

2. The “Big Picture” Goal Use DNA to make protein
Step 1: Replicate the DNA
Step 2: Transcribe DNA into RNA
Step 3: Translate RNA into protein
Today is all about step 2: TRANSCRIPTION

3. What Does it Mean to “Transcribe” something?
The definition: to make a written copy of something
The scientific definition: when RNA polymerase uses one strand of DNA as a template, from which nucleotides are assembled into a strand of RNA in the nucleus
The “in our own words” definition: using DNA to make RNA

4. Things to Keep in Mind: All of our traits come from our genes
Genes are special segments of our DNA that code for 1000’s of very specific different proteins
Human DNA is estimated to have 20, ,000 different genes!

5. Transcription
An enzyme called RNA polymerase finds the beginning of a gene
RNA Polymerase
DNA Molecule
Gene

6. Transcription RNA polymerase moves down the gene and…
Unwinds the DNA molecule into 2 temporarily separated strands
“Reads” one of the strands of DNA and pairs free floating nucleotides to it forming a new single strand of mRNA
Direction of Movement
New single strand of mRNA

7. Transcription RNA polymerase reaches end of gene
RNA polymerase detaches
New strand of RNA detaches from DNA template
RNA Polymerase
DNA Molecule
Completed new strand of mRNA

8. RNA Stands for ribonucleic acid Single stranded
Has a phosphate, ribose sugar, and base in each nucleotide
Made from 4 different bases:
Guanine (G), cytosine (C), adenine (A), uricil (U)

9. Practice:
If RNA polymerase were to find a gene, move down the gene unwinding the double stranded DNA, read the template strands to be this:
A G G C T A T T G C A
what would the sequence of the new strand of RNA be?

10. Practice:
If RNA polymerase were to find a gene, move down the gene unwinding the double stranded DNA, read the template strands to be this:
A G G C T A T T G C A
what would the sequence of the new strand of RNA be?
U C C G A U A A C G U

11. Similarities Between Replication and Transcription
Both involve enzymes
Both pair matching bases together
Both occur in the nucleus

12. Differences Between Replication and Transcription
Copies ENTIRE strand of DNA
Copies BOTH sides of DNA
Adenine (A) matches with thymine (T)
Final product: same thing you started with
Copies only ONE gene of DNA
Transcribes ONE side of DNA
Adenine (A) matches with uracil (U)
Final product: new single strand of mRNA