I think B is no and C is yes but I just want to double check

I think B is no and C is yes, but I just want to double check. Thank you in advance!

14. (12 points) The drawing below shows a genetic of a bacterial operon map required for utilization of the sugar maltose. The letters \'P\' and \'O\' indicate the promoter and operator regions located upstream from the operon. malABC are three genes in the operon. malA encodes a maltose transport protein, malB encodes an enzyme that hydrolyzes maltose into two glucose molecules, and malCencodes a maltose repressor protein that binds to the operator site of the operon. malC N malB mal4 (b) Would a mutant strain lacking maIA be able to utilize maltose? Answer: YES NO (c) would a mutant strain lacking to utilize maltose? Answer: YES NO maIC be able

Solution

Answer:

14.

(b) No

malA encodes for the maltose transporter protein. When maltose is present in the media, maltose in native form or its derivative (similar to allolactose) binds to the malA transporter and taken up by the cell.

If malA is lacking, maltose will not be taken up by the cell from the media. So, the operon doesn\'t get induced.

(c) Yes

malC encodes for the maltose repressor which binds to the operator when maltose is absent, i.e, the cells do not require malB to produce the enzyme required for hydrolyzing maltose. Binding of the repressor to the operator halts transcription of the downstream genes since RNAP cannot bind to the promoter.

If the cell lacks malC, the operon will not be repressed and the transcription of the downstream genes can take place. Thus, the cells can utilize maltose.