Week 9 - How cells harvest chemical energy

Question 1

What are the three main stages of cellular respiration & where does each stage occur inside the cell?

Answer 1

1. Glycolysis → cytoplasm
2. Krebs Cycle → mitochondrial matrix
3. ETC → mitochondrial membrane

Question 2

What are the end products of glycolysis?

Answer 2

Two each of:

1. Pyruvate
2. Net ATP
3. NADH

Question 3

Where do the end products of glycolysis go in order to continue in the process of cellular respiration?

Answer 3

1. Pyruvate goes to the Kreb’s cycle in the mitochondria
2. NADH goes to the ETC in mitochondria (ability to transfer electrons)

Question 4

What supplies the activation energy for glycolysis?

Answer 4

2 ATP spent to start the process of glycolysis

Question 5

Where does the carbon dioxide (CO2) that you breathe out actually come from in the cell respiration process?

Answer 5

CO2 is a remodeling of products of glucose breakdown.

(Literally from the C6H12O6 of original glucose)

Question 6

Where does the water produced in the process of CHO metabolism come from?

Answer 6

O2 acts as a (H+) and (e-) acceptor at the end of the ETC inside the mitochondria.

(e-) = electron

Question 7

Would a cell that lacked mitochondria be able to produce ATP? Why or why not?

Answer 7

Yes –
~ if they can do glycolysis and prokaryotic cells can do ATP production with an ETC that is embedded in the cell membrane, even though they lack mitochondria.

Question 8

During which of the thre e major phases of CHO metabolism are NADH &/or FADH2 being produced, and how were the original molecules (NAD+ & FAD+) changed to become these products?

Answer 8

1. NADH → Glycolysis & Krebs cycle
   NAD+ pickup (H+) = NADH
2. FADH2 → Krebs only
   FAD picked up 2 (H+) and makes → FADH2

Question 9

How do NADH & FADH2 contribute to the production of ATP in the final stage of cellular respiration?

Answer 9

1. They donate (H+) and (e-) from prior steps (glycolysis & Krebs cycle) to ETC →
2. → where (e-) moves from high energy state to a low-energy
3. And the mitochondria uses the released energy to do active transport of (H+) across the membrane
4. (H+) gradient is then used to synthesize ATP from ADP & Pi

Question 10

Which phase of CHO metabolism:

Generates most of the ATP formed by cellular respiration.

Answer 10

Electron Transport Chain

Question 11

Which phase of CHO metabolism:

Occurs outside the mitochondrion.

Answer 11

Glycolysis

Question 12

Which phase of CHO metabolism:

Produces ~32 ATP for each molecule of glucose broken down.

Answer 12

Electron Transport Chain

Question 13

Which phase of CHO metabolism:

Here electrons and hydrogen atoms combine with oxygen to form water.

Answer 13

Electron Transport Chain

Question 14

Which phase of CHO metabolism:

Will happen in the absence of oxygen.

Answer 14

Glycolysis

Question 15

Which phase of CHO metabolism:

When carbons from original glucose are released as a gas, we breathe out.

Answer 15

Krebs Cycle

Question 16

_____is consumed and _______ is produced in the overall process of cellular respiration.

a. CO2…H2O
b. O2…glucose
c. H2O…ATP
d. glucose…CO2
e. ATP…O2

Answer 16

d. glucose…CO2

Question 17

The energy given up by electrons as they move through the ETC is used to:

a. break down glucose
b. makes NADH & FADH2
c. pump (H+) through a membrane
d. oxidize water
e. manufacture glucose

Answer 17

c. pump (H+) through a membrane

Question 18

In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and in a few minutes radioactive oxygen atoms showed up in:

a. carbon dioxide
b. NADH
c. water
d. ATP
e. oxygen

Answer 18

a. carbon dioxide

Question 19

In a second experiment, mice were allowed to breathe oxygen gas (O2) laced with radioactive oxygen. In this experiment, the radioactive oxygen atoms quickly showed up in:

a. carbon dioxide
b. NADH
c. water
d. ATP
e. glucose

Answer 19

c. water

Question 20

Every time you make ATP, you also make _____.

Answer 20

water