1. Gene Expression
1. Gene expression is the activation of a gene that results in transcription and the production of mRNA.
Only a fraction of any cell’s genes are expressed at any one time.

2. Gene Expression in Prokaryotes
2. An operon is a series of genes that code for specific products and the regulatory elements that control these genes. In prokaryotes, the structural genes, the promoter, and the operator collectively form an operon.

3. Gene Expression in Prokaryotes
3. Structural Genes at code for specific products, such as polypeptides.

4. Gene Expression in Prokaryotes
4. A promoter is the segment of DNA that is recognized by the enzyme RNA polymerase, which then initiates transcription.
5. An operator is the segment of DNA that acts as a “switch” by controlling the access of RNA polymerase to the promoter.

5. Gene Expression
6. Repressor proteins are coded for by regulator genes and these proteins inhibit genes from being expressed. They attach and physically block the advancement of RNA polymerase.

6. Gene Expression
7. An Inducer is a molecule that initiates gene expression by binding to the repressor protein causing it to detach. RNA polymerase can then advance to the structural genes.

7. Lac Operon Video

8. Central Framework of Molecular Biology
DNA
RNA
Protein
Trait

9. Transformation Procedure Overview
Day 1
Day 2

10. What is a plasmid? A circular piece of autonomously replicating DNA
Originally evolved by bacteria
May express antibiotic resistance gene
or be modified to express proteins of interest

11. Bacterial DNA
Bacterial cell
Plasmid DNA
Genomic DNA

12. Gene Expression Beta Lactamase Ampicillin resistance
Green Fluorescent Protein (GFP)
Aequorea victoria jellyfish gene
araC regulator protein
Regulates GFP transcription

13. Recombinant DNA
Both the plasmid and target gene were cut using the same restriction enzyme. Since the sticky ends would easily bond together, the target gene was spliced into the plasmid DNA.

14. What is Transformation?
Cell wall
GFP
Uptake of foreign DNA, often a circular plasmid
Bacterial
chromosomal DNA
pGLO plasmids