glycolysis

Question 1

two forms of inorganic arsenic

Answer 1

reduced (trivalent As (III)) and oxidized (pentavalent As(V)), can be absorbed, and accumulated in tissues and body fluids.

Question 2

structure of arsenic

Answer 2

• The poison Arsenic (As[V])is structurally very similar to phosphate, the P part of ATP (the molecule that cells use as immediate energy).

Question 3

arsenic poisoning can be either what or what

Answer 3

acute (from one big dose), or chronic (the old something-in-the-nightly-cocoa routine).

Question 4

arsenic effects

Answer 4

• Arsenic has the same effect on insects, so it’s used in agricultural insecticides, and in treated-wood (like on a deck).

Question 5

arsenic in glycolysis

Answer 5

It takes the place of phosphate, blocking the step in ATP formation that traps the energy from respiration.

In normal condition, glyceraldehyde-3-phosphate (3C) is converted to 1,3-bisphosphoglycerate.

1,3 bi(s)phosphoglycerate is then converted to
3-phosphoglycerate, releasing one molecule of ATP.

However, when there is an arsenate, glyceraldehyde-3-phosphate is converted to 1-arseno-3-phosphoglycerate, an analogue of 1,3-bi(s)phosphoglycerate.

This analogue hydrolyses non-enzymatically into 3-phosphoglycerate to release arsenate back with no release of ATP. The overall result is that no net ATP is formed.

Normally, 4 molecules of ATP are formed per glucose molecule; 2 ATP molecules at the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and 2 ATP molecules at the conversion of phosphoenolpyruvate to pyruvate.

However, two molecules of ATP are used; one at phosphorylation of glucose molecule and one at phosphorylation of fructose-6-phosphate.