Only the proteins that the bacteria escherichia coli (e. coli) needs are synthesized at any given time. for example, when lactose is available in the environment, e. coli will express the lac genes that allow it to break down lactose to obtain energy. when lactose is not present, these genes are not expressed.

this prevents the lac genes in the dna of e. coli from being expressed most of the time.
a. the lac repressor
b. the lac operator
c. the lac promoter
d. the lac locator

Grade 91.)the gravitational pull from the moon words).2.) what is the rate of gravitational 3.)if you drop a hammer, is it more likely to drop handle side down, head side down, or equal chance that it will land either way? why? 4.)a car moves 60km east and 90km west.a.) what is the distance the car traveled? b.) what is the car's displacement5.)what is the average velocity of a car that moved 60 km south in 3 hours? 6.) a car starts from rest and acceleration to 60 m/s over a time of 5 seconds. what is the acceleration of the car? 7.)what is the speed of an object at rest?