Chapter 18 AP BIO

  1. What are genes controlled by 

  1. Operons

2. What is a operator  

  1. The “switch” that controls dna transcription 

3. What is the operator  

  1. A segment of dna locator in the promoter 

4. How many genes can a operator control 

  1. 1- several related genes 

5. What is a operon 

  1. Operator + promoter + genes 

6. What is a repressor

  1. The “switch” protein 

  2. What binds to the operator 

7. What happens if the repressor is attached to the operator

  1. Operon is repressed or “turned off” 

8. What happens if the repressor is not attached to the operator

  1. Operon is not repressed or “ turned on” allowing for the gene  to be transcribed 

9. Review figure 18.3

10. Where is regulatory genes located 

  1. Away from operon 

11. What do regulatory genes do 

  1. Code for repressor/ “switch” proteins

  2. Continuously make the proteins 

12. What do repressible operons do

  1. Operon are turned on by default 

  2. No reppressor attached to operator 

  3. RNA polymerase can attach and transcribe 

  4. To turn off a repressor protein attaches to operator 

13. What  happens when a repressor protein is turned off 

  1. Blocks RNA polymerase attachment 

  2. It is reversible 

  3. Allosteric  protein 

  1. Active and inactive shapes 

  2. Inactive state by default 

  3. Corepressors needed to activate 

14. What do the allosteric proteins do 

  1. When activated, corepressor inhibits transcription of a specific gene. 

15. What are the qualities of inducible operons 

  1. Operons are turned off by default 

  2. Reperessors attach to operator to turn on an inducer bonds inactivating it 

  3. Allosteric protein are active at default 

16. What is an example of an inducible operon

  1. Lac operon 

17. What needs to happen when glucose is lacking but lactose is present

  1. Bacteria need to change energy source 

  2. Must have enzymes to break down lactose 

18. What does increases when glucose is lacking

  1. cAMP [ ] increases 

19. What does cAMP do 

  1. Activates CAP

20. What is CAP

  1. An activator 

21. What does CAP do 

  1. Binds to promoter of lac operon 

  2. Increases affinity of RNA polymerase for promoter of lac operon 

  3. Increase rate of transcription 

22. What kind of control is lac operon under

  1. Dual control 

23. What is the negative controller of lac operon 

  1. Lac repressor 

24. What does lac repressor do 

  1. Determines whether lac operon is transcribed at all 

25. What is positive control of lac operon by 

  1. CAP

26. What does CAP do in lac operon 

  1. Determine the rate of transcription 

27. What state is dna found in in non dividing cells 

  1. Chromatin 

28. What are the two types of chromatin 

  1. Heterochromatin 

  2. Euchromatin 

29. What is heterochromatin 

  1. Very tightly compacted chromatin 

30. What is euchromatin 

  1. Less tightly compacted chromatin 

31. Why does histone modification occur 

  1. Dut to the histones bonding with neighboring nucleosomes 

32. What happens in histone modification 

  1. Chromatin becomes tightly compacted 

33. What happens in histone acetylation 

  1. Acetyl groups (-COCH3) attaches to histones 

  2. Heterochromatin loosens into euchromatin 

  3. DNA transcription can occur 

34. What happens in DNA methylation 

  1. Certain DNA bases become methylated 

  2. 35. What does DNA methylation do 

    1. Prevents transcription 

    36. What could DNA methylation be a cause of 

    1. Cell differentiation 

    37. What can DNA methylation be passed on through 

    1. Cell division