positive control, negative control, repressor protein, transcription factor initiation, action of the operator, RNA polymerase

1. Describe: gene control b.stev

3. bacteria need to make specific enzymes to utilise lactose as a nutrient lactose binds to the repressor protein & prevents it from attaching to the DNA, thus allowing transcription to occur POSITIVE CONTROL: repressor protein attachment to the operator is prevented via chemical interaction: ie: presence of lactose (sugar) in the environment (Campbell N. A, Reece J. B, 2005)

4. when the REPRESSOR PROTEIN binds to the OPERATOR it prevents transcription regulatory gene operator structural genes promoter TRANSCRIPTION FACTOR OPERON RNA polymerase direction of transcription = lactose binds , allows transcription to occur

6. the REPRESSOR PROTEIN binds to OPERATOR & prevents transcription regulatory gene operator structural genes promoter TRANSCRIPTION FACTOR (1) OPERON RNA polymerase direction of transcription

7. RNA polymerase can not move over the DNA strand: prevents transcription regulatory gene operator structural genes promoter TRANSCRIPTION FACTOR (2) - negative control RNA polymerase direction of transcription

8. Bibliography Campbell N. A, Reece J. B. (2005). Biology (7th ed.) . San Francisco: Benjamin Cummings Pommerville J.C. (2004). Alcamo’s – Fundamentals of Microbiology (7 th ed.). Massachusetts: Jones and Bartlett. Wikipedia. (2008). Gene expression – wikipedia, the free encyclopedia . Retrieved October 23, 2008, from http:www. en.wikipedia. org/wiki/ Gene _ expression - 49k -