1. A gene is a segment of DNA that holds the ‘directions’ for a certain physical trait such as eye color
The ‘directions’ contained on a gene or genes tells a cell how to make a certain protein
The way that the protein is made determines the way the trait is expressed

2. Only a fraction of genes in a cell are
expressed (made into RNA) at any given time.
How does the cell decide which will be turned on and which will stay “silent”?
Promoter regions that show RNA polymerase where to start.
There are other Regulatory sites that
control whether a gene is ON or OFF.

3. Group of genes that operate together are called an Operon
When an Operon is turned OFF a repressor molecule binds to the operon, blocking RNA polymerase
When and Operon is turned ON the repressor molecule is released and RNA Polymerase is allowed to copy the genes

4. GENE is turned
“ON”

5. RNA Structure Also made of nucleotides
RNA is single stranded allows it to leave the nucleus while DNA cannot
Contains Uracil instead
of thymine A-U
G-C
There are three kinds of RNA: rRNA, tRNA, mRNA

6. Reading the codes DNA is copied by mRNA
mRNA’s code is then translated into amino acids
Remember A-T (U)
G-C
Translate this DNA code into mRNA code: GAGTTCACGTTG
mRNA code:

7. Now translate the mRNA code into amino acids using the chart
CUCAAGUGCUUC
Leu
Lys
Cys
Phe

8. DNA Structure in Prokaryotes
Approximately 5 million base pairs (3,000 genes)
DNA molecule in bacteria is circular
& found in the cytoplasm
Prokaryotes have NO nucleus!

9. The Human Genome The complete genetic code for humans is now known
The Human Genome project has deciphered the order of the 3.2 billion base pairs in the 23 human chromosomes
Now scientists are working on learning about how and where all the different proteins coded for on our DNA is being used

10. The Human Genome
This information is important in research for the cause, treatment & prevention of disease

11. The End
Hooray! We are done!