Cellular Respiration

Question 1

What is the first step of cellular respiration?

Answer 1

Glycolysis

Question 2

What is the second step of cellular respiration?

Answer 2

the Krebs cycle

Question 3

What is the Third step of cellular respiration?

Answer 3

Electron transport chain

Question 4

Glycolysis phase

Answer 4

1. Prepatory phase: 2 ATP phosphorylate Glucose making it less stable. Glucose is broken down into 2 (3 carbon) molecules.
2. Payoff phase: the 2 3carbon molecules become phosphorylated again giving off e- and H+ (2 e- and 1 H+) and donating them to 2 NAD+. Reducing NAD+ to NADH.
3. More bonds from the 2 halves of glucose are broken, the energy released by the breaking down of the molecules is then capted in the phosphorylation of ADP. As a result 2 ATP are made; making up for the 2 used ATP earlier.
4. 2 molecules of water are also produced
5. The 2 remaining phosphate groups on the 3 carbon molecules are added to 2 ADP molecules creating 2 more ATPs; so far 4 ATPs have been produced, with a net gain of 2 ATPs.
6. The 2 molecules are now transformed into pyruvate. There is still much more energy in the bonds of pyruvate.

Question 5

Where does glycolysis occur? What happens during glycolysis?

Answer 5

• in the cytoplasm of the cell regardless of what type of cell.
• Glocose (6 Carbon) is split into 2 (3 carbon) molecules.

Question 6

what is the difference between NAD+ and NADH?

Answer 6

• NADH has one more proton and 2 e-
• The other H+ is released into surrounding medium.

Question 7

Krebs Cycle phase

Answer 7

1. pyruvate molecules must enter the mitochondrion.
2. Pyruvate is modified by NAD+ and CoA (coenzyme A)

• in one of the steps CO₂ is released from pyruvate and exhaled by the body.
• The 2 carbon molecule that remains is attached to CoA; this causes a H+ and 2 e- to be released and donated to NAD+ turning it into NADH; The new molecule is called Acetyl CoA

3. 2 acetyl CoAs are formed, 2 NADH are formed and 2 CO₂ are formed for both pyruvates that undergo this process.
4. Both Acetyl CoA enter the kreb cycle where the 4 remaining carbons are transformed into CO₂
5. Acetyl CoA combines with H2O and oxaloacetate. The water hydrolyzes the CoA and the 2 carbons from the Acetyl combine with the oxaloacetate 4 carbons of the Oxaloacetate to form citric acid.
6. The 6 carbon citric acid is rearranged by the the removal and addition of water.
7. The citric acid is stripped of 2 carbon molecules that leave as CO_2, the proton and e- from the reaction are then picked up by NAD+ creating NADH.
8. Energy from the remaining molecule is then used to phosphorylate ADP to make ATP. 2 Protons and 2 electrons are donated to FAD to make FADH₂
9. The addition of water rearranges the molecule back into oxaloacetate and donates 1 proton to and 2 e- to NAD+ reducing it to NADH.
10. the whole thing occurs again with the 2nd acetyl CoA molecule.
11. All together 6 NADH are made, 2 FADH₂ are made in the krebs cycle, also 4 CO₂ and 2 ATP. Combined with the electron carriers from glycolysis we now have 8 NADH, 2 FADH₂, 6 CO₂, and a net gain of 4 ATP.

Question 8

What is the point of glycolysis?

Answer 8

To turn glucose in pyruvate.

Question 9

which part of respiration create the most ATP?

Answer 9

• Electron Transport chain

Question 10

What is necessary for the ETC to opperate why?

Answer 10

• Oxygen
• Oxygen is electronegative and drive the ETC
• Oxygen is the final e- acceptor.
• The krebs cycle depends on the e- to be removed from NADH and FADH₂ in the ETC without e- removal there is no free NAD+ or FAD to continue the Krebs cycle. Both ETC and Krebs cycle will shut down.

Question 11

Electron Transport Phase

Answer 11

1. NADH and FADH₂ donate e- to the ETC
2. As the electrons pass from protein to protein (a series of redox reactions) they energize the proteins and cause them to pump out H+ to create a concentration gradient (more H+ on the outside and less H+ on the inside) this is potential energy.
3. NADH and FADH₂ are oxidized and become NAD+ and FAD again and return back to the krebs cycle to pick up more e- for the ETC.
4. Electronegative oxygen then binds with the e- at the end of the ETC. And then combines with H+ to form H₂O
5. The protons will flow through ATP synthase back into the mitochondrial matrix or back intothe cytoplasm because they want to move down their concentration gradient to get away from other H+ (like charge repulsion).
6. The energy of the protons flowing through ATP synthase will phosphorylate ADP.
7. If the ETC stops for any reason like lack of O2 the concentration gradient will dissapear and oxidative phosphorylation will stop (NO ATP production) the organism will only get ATP from fermentation pathways.

Question 12

where does the ETC take place?

Answer 12

The inner membrane of the mitochondria or the plasma membrane in prokaryotes.

Question 13

Where does the krebs cycle take place?

Answer 13

• in the mitochondrial matrix of eukaryotes
• or in the cytoplasm of prokaryotes

Question 14

What is the purpose of the ETC?

Answer 14

• To create large amounts of ATP
• it uses e- energy to power proton pumps to create a concentration gradient, which then powers ATP synthase.

Question 15

What is the purpose of glycolysis?

Answer 15

• To split glucose into pyruvate
• which is then turned into acetyl CoA in prep for the krebs cycle

Question 16

What is the purpose of the krebs cycle?

Answer 16

• to reduce NAD+ and FAD to NADH and FADH₂ So their associated e- can be used in the ETC.