1. Name the four different types of gene mutation. Identify the ones that can potentially be more harmful and give a reason for why. Point mutations: these are only minor mutations that will affect the organism only slightly or not at all Substitution Inversion Frameshift mutations: these lead to major changes as large portions of DNA are misread Insertion Deletion

2. Homework LP 18 due in today No homework = detention  New homework – Due Thursday 28 th November

3. 25 November 2015 Aims: (h) explain genetic control of protein production in a prokaryote using the lac operon; Today’s Title: The lac operon RWCM: write notes to describe how protein synthesis can be controlled Key phrases/words Regulator gene Lactose permease Structural gene Promoter region Operator gene Repressor protein Operon Control sites ß-galactosidase

4. How is protein synthesis controlled?

5. What you need to know Explain the genetic control of protein production – using the lac operon as an example Key terms you need to know....... Operon – length of DNA made from structural genes and control sites Structural genes – code for protein Control sites – operator and promoter region of the DNA

6. The lac operon We know that....... mRNA – codes for a particular protein The code on the mRNA is complementary to the base sequence on the DNA template strand Therefore that code on the mRNA is a copy of the base sequence on the DNA coding strand Proteins are specified by mRNA

7. Background information Bacteria can synthesise different enzymes (proteins) depending on what food substrate they are growing on E.Coli can synthesise over 3000 different enzymes Enzymes involved in basic cell functions are synthesised at a constant rate Inducible enzymes are synthesised as and when they are needed

8. What is enzyme induction? Discuss what you think this means and why it is important – you have 2 minutes Share your thoughts with the class.

9. Background information E.Coli can adapt to its environment by producing enzymes to metabolise certain nutrients.......... but only when those particular nutrients are present E.Coli normally respires using glucose but can also respire using lactose (sugar found in milk/disaccharide) Needs to synthesise ß-galactosidase & lactose permease

10. Background information ß-galactosidase – hydrolyses lactose into glucose & galactose lactose permease – transport protein that becomes embedded in the e.coli membrane – helps transport more lactose into the cell When placed in a lactose substrate, e.coli increases the synthesis of these two proteins by 1000x Lactose triggers the enzymes production – inducer molecule

11. Task 1 Make flash cards of the following words with definitions on the back. Regulator gene Lactose permease Structural gene Promoter region Operator gene Repressor protein Operon Control sites ß-galactosidase Learning objectives explain genetic control of protein production in a prokaryote using the lac operon;

12. Mini Plenary Match the components with the functions ComponentFunction A. Structural Gene1. Produces repressor protein B. Regulatory gene2. Binds to repressor C. Promoter3. Codes for lac enzymes D. Operator4. Binds to RNA polymerase

13. The lac operon Lac system genes (in the bacterial DNA) form the operon – consists of structural genes and control genes. Z - ß-galactosidase Y - lactose permease O – operator region – switches Z & Y on and off P – Binding site for RNA polymerase for transcription of Z & Y

14. If lactose is absent Regulator gene is expressed and produces repressor protein Repressor protein binds to the operator region (P & O) Partially covers the promoter region (P) RNA polymerase can’t bind – Z & Y genes can’t be translated Z & Y are switched off

15. If lactose is present Inducer molecule (lactose) binds to the repressor protein Repressor protein dissociates from the operator region Promoter is now unblocked RNA polymerase can now bind promoter region Z &Y can now be transcribed – mRNA produced ß-galactosidase /lactose permease can now be synthesised

16. The lac operon As a result of the 2 enzymes being made, e.coli can now..... Take up lactose from its environment because lactose permease acts a transport protein. Using ß-galactosidase, lactose (disaccharide) can hydrolysed into glucose & galactose E.coli can use these sugars for respiration E.coli is gaining energy from the lactose

17. Mini Plenary What are the functions of: Repressor protein RNA polymerase Regulatory gene http://www.youtube.com/watch?gl=GB&v=oBwtxdI1zvk

18. Task 2 Get into groups of 3 or more Use the large A2 paper as a story board Each person is to cut out the parts of the lac operating system on the handout provided Arrange the cut out parts to show the story of how the lac operon works in both the absence and presence of lactose