BIOL2171 Lecture Notes - Lecture 4: Dihydroxyacetone Phosphate, Phosphoenolpyruvic Acid, Citric Acid Cycle

Q1:

Enzymes are essential for the conversion of organic molecules in biochemical pathways. Which of the following statements is incorrect?

Enzymes reduce the activation energy of chemical reactions.

Enzymes are catalysts and appear unchanged at the end of the reaction.

Enzymes change the equilibrium of a reaction.

Enzymes form a complex with the substrate.

Enzymes facilitate both the conversion of substrates into products and of products into substrates.

Q2:

NADH and NADPH are important energy carriers in biochemical pathways. Which of the following statements about these compounds is incorrect?

NADP+ is reduced by two electrons (involving 2 protons) from photosystem I to form NADPH + H+.

NADH is produced both during glycolysis and in the TCA cycle.

NADH feeds electrons into the respiratory chain of mitcohondria, which are ultimately used to form water.

In the absence of oxygen NADH produced during glycolysis is reoxidised by formation of lactate from pyruvate or by formation of ethanol from acetaldehyde (fermentation).

The majority of NADH produced during oxidation of glucose (in the presence of oxygen) is generated during glycolysis.

Q3:

The respiratory chain converts the reducing power of NADH into the production of ATP. Which of the following statements is incorrect?

Electrons are passed through the respiratory chain in a way to optimise the production of heat.

The complexes of the respiratory chain use the energy of redox reactions to pump protons across the inner mitochondrial membrane.

The ATP synthase uses the protonmotive force to synthesize ATP.

The principle of energy conversion by respiratory chain and ATP synthase is called “chemiosmosis”.

The electrons from NADH are passed along the respiratory chain in a number of redox reactions mostly involving complexes

Fill in the blank with either the word reduce/reduced or oxize/oxidized in the appropriate blank

The primary purpose of glycolysis is to ____________________ glyceraldehyde-3-phosphate in a coupled reaction that fuels ATP synthesis. The final product pyruvate is later removed from the cell as waste in either the ____________________ form of lactate or the ____________________ form of CO2 depending on the availability of an inorganic electron acceptor. A primary purpose of fermentation is to ____________________ NADH+ in order to support continuing glycolysis in the absence of oxygen. However, when oxygen is present NADH+ will serve as the initial electron donor to the respiratory chain and become ____________________ by the NADH dehydrogenase complex. Membrane-bound quinones shuttle electrons between a(n) ____________________ NADH dehydrogenase complex and a(n) ____________________ cytochrome C complex with a higher reduction potential. As a final electron acceptor of the respiratory chain, oxygen is ____________________ to form water

Thank you