A&P Lecture 3 Exam

Describe cellular respiration in detail

Consists of glycolysis, pyruvate oxidation, the citric acid cycle, and is followed by the ETC (electron transport chain). In these processes, a molecule of glucose is broken into 2 molecules of pyruvate, and is used to generate electron carriers, nicotinomide (NADH) and flavindinucleotide (FADH2). The ETC uses both NADH and FADh2 as electron donors, in a series of oxidation and reduction reactions.

What do oxidation and reduction reactions do?

• Oxidation and reduction reactions facilitate the movement of electrons.

• When a molecule is oxidized it loses electrons, and when reduced it gains electrons

Describe ATP and its involvement in Cellular Respiration

• ATP is adenosine triphosphate

• When the terminal phosphate is broken off ~7 kcal/mol are realessed and the molecule becomes Adenosinediphosphate (ADP)

• The phosphate broken off is called Pi with the i meaning “inorganic”

• The delta G for ADP + Pi —> ATP is positive and requires an enzyme to overcome the delta G

What two enzymes in cellular respiration add ADP and Pi together?

• ATP synthase, which generates the majority of ATP in the ETC

• Kinase enzymes seen in glycolysis and the citric acid cycle

What are the proton pumps, and the electron carriers in the ETC

• the proton pumps are NADH Dehydrogenase, cytochrome bc1 and cytochrome oxidase

• The electron carriers are ubiquinone (Q), and cytochrome C

Describe the ETC in detail

• series of oxidation and reduction reactions which occur in the inner membrane of the mitochondria

• The inner membrane space (IMS) has more protons (H+) than the matrix, which creates a gradient, which is potential energy

• Electrons re donated by the 2 electron donors- NADH and FADH2

• NADH donates 2 electrons to NADH Dehydrogenase complex, which powers it on nd causes it to pump 2 H+ from the matrix to the IMS

• The 2 electrons are carried to the 2nd pump, cytochrome bc1, by the electron carrier Ubiquinone (Q)

• The 2nd pump powers on and pumps 2 H+ from th4 matrix to the IMS

• The electrons are carried one at a time with cytochrome C, to the pump Cytochrome oxidase

• Cytochrome oxidase needs 4 electrons to work

• The other two electrons can be donated by another NADH or an FADH2 that donates to the second pump cytochrome bc1

• Cytochrome oxidize pumps 4 H+ from the matrix to the IMS

• The last electron acceptor is oxygen which combines with 4H+ and 4 electrons to make two H2O

What happens to the potential energy used in the H+ gradient in the IMS ?

• it’s transferred to the ATP synthesis to make it spin, which is kinetic energy

• The kinetic energy is used by ADP +Pi, which have a positive delta G to combine into ATP

• ATP is a chemical potential energy which is transferred to heat energy when used

• Appropriately ~10H+ pumped equals 3.3 ATP

What do kinase enzymes do?

Can either use an ATP or produce an ATP. A phosphate can be taken from ATP or added to ADP to make ATP

What does isomerase do?

Enzymes that rearrange the connectivity of a molecule to crate an isomer. Sometimes they are called mutate enzymes

What do dehydrogenase enzymes do?

• are oxidation reduction enzymes

• In glycoside, pyruvate oxidation, and the citric acid cycle dehydrogenase produce NADh and FADH2

• These enzymes take electrons from intermediates and give them to NAD+ (oxidized) and FAD (oxidized) to produce NADH (reduced) and FADH2 (reduced)

• So NADH and FADH2 drop off electrons at the electron transport chain, and pick them up in glycolysis, pyruvate oxidation, and the citric acid cycle