1. Transcription
Using DNA to make RNA

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

3. 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

4. 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

5. 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?

6. 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

7. Using RNA to make Protein
Translation
Using RNA to make Protein

8. Kinds of RNA Before we talk about translation, you should know:
There are 3 types of RNA involved in the process of making protein
mRNA: messenger RNA carries the message of how to make a protein (this is the one we talked about in transcription!)
tRNA: transfer RNA transfers amino acids to the ribosome during translation
rRNA: ribosomal RNA is one small piece making up the ribosome

9. Kinds of RNA
mRNA

10. Kinds of RNA tRNA Amino Acid Folded RNA Strand Anticodon
(complementary to the mRNA codon)

11. Kinds of RNA
rRNA
Ribosomal RNA
Ribosome

12. The Genetic Code On the mRNA molecule, bases are read 3 at a time
A group of 3 bases in a row is called a codon
There are 64 possible different codons that code for the 20 different amino acids
codon for
methionine (Met)
leucine (Leu)

13. The Genetic Code
How do you know which codons code for which amino acids?
Use the sheet I will pass out now!!!

14. The Genetic Code AUG is the start codon UAA, UAG, UGA are stop codons
This is where translation will begin
UAA, UAG, UGA are stop codons
This is where translation will end

15. Practice translating codons:
Codon=3 nucleotides that are read together
If this is the strand of mRNA:
UCGCACGGU
The codons are:

16. Practice translating codons:
Codon=3 nucleotides that are read together
If this is the strand of mRNA:
UCGCACGGU
The codons are:
UCG-CAC-GGU

17. Practice translating codons:
Codon=3 nucleotides that are read together
If this is the strand of mRNA:
UCGCACGGU
The codons are:
UCG-CAC-GGU
How many codons are there?

18. Practice translating codons:
Codon=3 nucleotides that are read together
If this is the strand of mRNA:
UCGCACGGU
The codons are:
UCG-CAC-GGU
How many codons are there? 3

19. Practice translating codons:
Codon=3 nucleotides that are read together
If this is the strand of mRNA:
UCGCACGGU
The codons are:
UCG-CAC-GGU
How many codons are there? 3
What amino acids are coded for?

20. Practice translating codons:
Codon=3 nucleotides that are read together
If this is the strand of mRNA:
UCGCACGGU
The codons are:
UCG-CAC-GGU
How many codons are there? 3
What amino acids are coded for?
Serine, Histadine, Glycine

21. The Process mRNA molecule leaves nucleus and binds with ribosome
Beginning at the start codon, ribosome binds tRNA molecules with mRNA molecules according to correct codon—anticodon pairing
So for example, if the codon GAC is on the mRNA molecule, a tRNA molecule with the anticodon CUG will bind to it
The tRNA molecule brings its amino acid, which the ribsosome will bind to other amino acids being brought in to make a polypeptide chain (protein)