A number of nutritional mutant strains were isolated from wild-type Neurospora that responded to the addition of certain supplements in the culture medium by growth ( + ) or lack of growth ( -). Given the following responses for single gene mutations, diagram a metabolic pathway that could exist in the wild-type strain that is most consistent with the data. Indicate where the pathway is blocked in each mutant strain.

#Question id: 3649

#Unit 3. Fundamental Processes

In eukaryotes, clusters (tandem arrays) of about 20–50 replicons initiate simultaneously at defined times throughout:

#Question id: 12316

#Unit 10. Ecological Principles

#Question id: 12652

#Unit 6. System Physiology – Plant

#Question id: 10342

#Unit 6. System Physiology – Plant

Nitrate reductase is an important enzyme for nitrate assimilation. Given below some regulation of nitrate reductase activity through phosphorylation and dephosphorylation.

a) Light, and other environmental factors stimulate a protein phosphatase that dephosphorylates a key serine residue in the hinge 1 region of nitrate reductase and thereby activates the enzyme

b) In Dark, and Mg2+ stimulate a protein kinase that phosphorylates the same serine residues, which then interact with a 14-3-3 inhibitor protein, and thereby inactivate nitrate reductase

c) In Light, and Mg2+ stimulate a protein kinase that phosphorylates the serine residues, and thereby activate nitrate reductase

d) In Dark, and other environmental factors stimulate a protein phosphatase that dephosphorylates a key serine residue in the hinge 1 region of nitrate reductase and thereby inactivates the enzyme

Which of the following statements about regulation of nitrate reductase is correct?

#Question id: 5256

#Unit 8. Inheritance Biology

If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophage are excluded from the bacterial cultures, then which of these is a means by which beneficial mutations might be transmitted horizontally to other E. coli cells?