Molecular GeneticsAre we controlled by our Are we controlled by our DNADNA?Refer to pg 119-150 in Holtzclaw, Ch 16-21 in Campbell

Last year...Last year...What do you remember of DNA

Replication and Protein Synthesis?

DNA > mRNA > protein

genetic info message action molecule

So What?So What?Making the big connections...

◦How many cells do you have?◦Compare the DNA in each of your cells◦Compare the protein products in each

of your cells...

How does your body KNOW when to make some proteins and not others?◦THIS is gene expression

So What?So What?Model Organism: The Fruit Fly

So What?So What?More flies!

◦- Using Gene expression to study eye development

What do you think?What do you think?Are you controlled by your DNA?What are the implications of

studying Gene expression?

1) Free Write (3 min)2) Learning Walk (5 min)3) No Hands Discussion (5 min)

Review last year…Review last year…Learning Intentions!

Gene ExpressionGene ExpressionYou must know:

The functions of the three parts of an operon

The role of repressor genes in operonsThe impact of DNA methylation and

histone acetylation on gene expressionThe role of gene regulation in embryonic

development and cancer.

Gene ExpressionGene Expression

Rather important, don’t you think?:The functions of the three parts of an

operonThe role of repressor genes in operonsThe impact of DNA methylation and

histone acetylation on gene expressionThe role of gene regulation in embryonic development and cancer.

The Operon – The Operon – p. 131 in Holtz.p. 131 in Holtz.What is it?

◦Unit of genetic function◦Found in bacteria/phages/some

eukaryotes◦Consists of:

Promotor – site of RNA polymerase binding Operator – controls access of RNA

polymerase within the promotor Genes of the Operon –regulated together

by the operon

Regulatory GenesRegulatory GenesWhat do they do?

◦Produce repressor proteins that bind to the operator of an operon to block RNA polymerase from transcribing

Repressible Operon◦Usually “on,” can be inhibited...

Inducible Operon◦Usually “off,” can be induced...

The Try Operon – The Try Operon – Repressible Repressible

The Lac Operon – The Lac Operon – Inducible Inducible

Let’s make sure we get Let’s make sure we get this…this…