Chapter 6 HW

Consider the biochemical pathway: A~B~C Enzyme 1 catalyzes A~B Enzyme 2 catalyzes B~C If enzyme 2 is inactive, which of the following compounds will accumulate?

B only

All biochemical pathways have the same number of enzymatic reactions.

False

An enzyme speeds up a chemical reaction in the cell, but can only be used once. True or false

False

Which of the following binds to the active site of an enzyme?

Substrate

In prokaryotic cells, the electron transport chain (ETC) is located in the ___________, whereas in eukaryotic cells, the ETC is located in the ____________.

cytoplasmic membrane; inner membrane of mitochondria

The energy captured in the phosphorylation of ADP to ATP comes from the proton motive force created in respiration.

True

Statements that describe biochemical pathways?

- They only function for a few time - They convert an initial substrate through a series of into an end product -They are well-organized and structured -They always run at their maximum rate.

Electron Transport Chain and Formation of ATP

How does cyanide kill you? The final stage of cellular respiration is the electron transport chain (ETC). The ETC is a series of electron carriers embedded in the mitochondrial membrane (cytoplasmic membrane in prokaryotes). The first carrier accepts protons and electrons from products of glycolysis and the TCA Cycle. The electrons are passed from carrier to carrier and finally react with oxygen and protons to form water. Without oxygen, the final reaction cannot occur. This causes a 'traffic jam' in that electrons further back on the chain cannot be transferred, stopping the entire process and preventing the generation of ATP. In a similar manner, cyanide prevents oxygen from binding to the final carrier in the electron transport chain. Individuals poisoned with cyanide die because the cells can no longer make ATP, even though their cells may have abundant oxygen.

Consider the biochemical pathway: A~B~C Enzyme 1 catalyzes A~B Enzyme 2 catalyzes B~C Enzyme 1 can utilize

Only A as a substrate

Enzymes are usually

Proteins

On a biochemical pathway, the product of the first reaction becomes the substrate in the second reaction.

True

In bacteria, protons received from NADH

are transported (or pumped) through the membrane to the outside of the cell.

In the electron transport chain, protons are pumped across the cell membrane. This results in

the formation of a proton motive force.

In aerobic respiration, oxygen acts as

the terminal electron acceptor.