What is the purpose of operons in protein synthesis? they transfer the mrna to the ribosomes for protein production. they unzip the dna molecule at the beginning of transcription. they contain promoters and operators that determine when a gene is transcribed.

An adult inhales about 6.0×10−4 m3 of fresh air during a breath. only 20% of fresh air is oxygen. assume the pressure in the lungs is 1.0×105 paand the air is at a temperature of 300 k. how many oxygen molecules are in each breath? a. 1.4x10^23 b. 2.9x10^21 c. 4.9x10^-4 d. 2.9 x10^25