Using site-directed mutagenesis, you have created a mutant form of chymotrypsin that has alanine substituted for the usual serine at position 195. Which of the following effects would your expect to observe? a. No effect or slight increase in affinity for substrate coupled to a complete loss of enzyme activity. b. A decrease in the affinity for substrate coupled to a decrease in enzyme activity. c. An increase in the rate of peptide-bond cleavage due to an increase in the rate of acid-base catalysis. d. An increase in the rate of peptide-bond cleavage due to an increase in the rate of covalent catalysis. e. A complete loss of enzyme activity due to the inability to bind substrate

The correct answer is - option E.

Explanation:

Serine may not be affected by the mutation as it has no part of the hydrophobic binding site so it won't affect the affinity of the binding of the substrate. The peptide bond-breaking would not occur without the catalytic end or part so the enzyme would be the complete loss of enzyme activity due to site-directed mutagenesis that is created from the chymotrypsin.

Thus, the correct answer is - option E.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!