1. DNA replication, transcription, & translation
How you go from DNA to proteins

2. Watson & Crick double helix
In 1953, Watson & Crick discovered the structure of DNA- the…
double helix

3. Remember DNA is in the nucleus of cells Chromosomes are made up of DNA
Where is DNA?
DNA is in the nucleus of cells
What is made up of DNA?
Chromosomes are made up of DNA

4. Remember as well… Before a cell divides (mitosis) it has to do what?
Copy its DNA, (and grow)

5. DNA replication An enzyme unzips (or takes apart) the double helix
Each strand acts as a template for the new strand
A T C G get added to the growing strand
An enzyme “proofreads” or double checks the new DNA to make sure there are no mistakes

6. Watch DNA replication

7. DNA contains genes Genes are parts of the DNA that code for traits
But how do we get from DNA to traits that we see?

8. First DNA is used to make RNA
This process is called transcription
RNA replaces T with U!
This type of RNA= messenger RNA, or mRNA

10. Watch transcription
Transcription

11. Review: Transcription
Enzyme unzips DNA
RNA polymerase starts transcription
RNA bases are matched to one strand of DNA
RNA strand is released

13. DNA is a double helix, RNA is not!

14. PRACTICE! Write the DNA strand: A C G G C T T A C T G G C A T T
Now you figure out the RNA strand.
Answer:
U G C C G A A U G A C C G U A A

15. Messenger RNA mRNA carries the message of your genetic code
It leaves the nucleus and goes into the cytoplasm where there are ribosomes

16. Serine-Histidine-Glycine
Genetic Code
Now you have mRNA carrying the genetic code
You read the sequence of letters 3 bases at a time: UCG-CAC-GGU
The 3 letter codes are called codons and stand for an amino acid: UCG-CAC-GGU
There are 20 amino acids that make up ALL the proteins in your body!
Serine-Histidine-Glycine

18. PRACTICE:
1. GCU AAA CGA UUC

19. From RNA to protein This process is called Translation
mRNA attaches to ribosome – rRNA found in ribosome acts as translator
tRNA anticodons match up with mRNA codons and carry the amino acid
The amino acids bond together to form a protein

22. Watch translation..TWICE!

23. REVIEW! DNA replication gives us: 2 copies of DNA
Transcription gives us:
mRNA
Translation gives us:
amino acid chain (protein!)
Proteins give us traits!