Question 3

[julyhorse6901]

Question is:

3) The enzyme which catalyzes the formation of glucan is likely located:

A. in the cytosol of the cocci.[x]
B. in lysosomes within the cytoplasm of the cocci.[x]
C. in the nuclei of the cocci.[x]
D. on the cell surface membrane of the cocci.

I see the reason for D, but I also reasoned for A as well. Since it says, "Streptococcus mutans produces glucan." It would seem that this cell 'produced' glucan, from within the cell and exocytosed out. I thought the cell would take sucrose, break it up inside the cell, and turn fructose into lactic acid, and then link the glucose into polymers, then exocytose it outside.

Is my logic valid as well?

Thanks

[mybirdnest7483]

I'm in the same boat as you, I picked A as well as it seemed more likely to me. From my knowledge, I only know certain bacteria found in milk can secrete enzymes to outside the cell and digest nutrients, but this is very rare in your garden variety bacteria. So I thought A is more likely than D. Also, the passage doesn't give enough information for this question to get the correct answer.

[admin]

The mechanism that julyhorse6901 describes is reasonable from a biological point of view but very inefficient for bacteria that replicate exponentially. The sucrose is outside of the bacterium and the glucan will have its function outside as well. So the best answer would point to an enzyme that is extracellular to do the most efficient conversion.

[HtbRodriguez]

Might be , and still not really important ...