Chapter 3

Question 1

when is NAD+/NADH used as a redox coenzyme? and when is NADP+/NADPH

Answer 1

NAD+/NADH -> common in microbial catabolism
NADP+ /NADPH -> anabolic redox reactions

Question 2

energy released in a coupled exergonic redox reaction goes where?

Answer 2

It is trapped by the cell and conserved in compounds containing energy-rich phosphophate or sulfur bonds.

Question 3

How can phosphate be bonded to organic compounds?

Answer 3

either ester or anhydride bonds

Question 4

What is the minimum charge of energyrich compounds that is typically used in metabolism?

Answer 4

delta G0’ of at least -30 kJ/mol.

Question 5

What does ATP consist of?

Answer 5

ribonucleoside adenosine with 3 PO43- bonded to it

Question 6

name another energy-rich compound otherthan phosphorylated ones? and how do they work?

Answer 6

compounds derived from Coenzyme A - e.g. acetyl-CoA.

they contain energy-rich thioester bonds; the hydrolysis of which yields sufficient free energy to be coupled to the synthesis of an energy-rich phosphate bond.

Acetyl-S-CoA + H2O + ADP + Pi -> acetate + HS-CoA + ATP + H+

thus energy released in the hydrolysis of coenzyme A is conserved when ATP is synthesized.

Question 7

Where are coenzyme A derivates especially important and why?

Answer 7

In anaerobic microorganisms especially in fermentation. ADD TO THIS LATER

Question 8

ATP is broken down when?

Answer 8

ATP is broken down to drive anabolic reactions and resynthesized at the expensive of catabolic redox reactions

Question 9

What is fermentation

Answer 9

form of anaerobic catabolism in which organic compounds both donate electrons and accept electrons; redox balance is achieved without the need for external electron acceptors

Question 10

What is respiration

Answer 10

form of aerobic or anaerobic catabolism in which an organic or inorganic electron donor is oxidised with O2 or another compound functioning as the electron acceptor.

Question 11

how is glucose oxidised to pyruvate?

Answer 11

Through glycolysis

Question 12

what happens to pyruvate during fermentation

Answer 12

it is not oxidized to CO2; rather it is used as an electron acceptor to achieve redox balance in glycolysis

Question 13

what are the 2 roles the citric acid cycle performs in the cell

Answer 13

glucose respiration coupled to energy conservation and it plays a role in the biosynthesis of key metabolites

Question 14

what oxidation-redox enzymes participate in electron transport?

Answer 14

NADH dehydrogenases, flavoproteins, iron-sulfur proteins and cytochromes. Also nonprotein electron carriers called quinones