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bio 123 lab exam #2 > Lab 5 > Flashcards

Lab 5 Flashcards

1
Q

Where in the cell do the following processes take place?

  • Glycolysis?
  • Citric Acid Cycle?
  • Electron Transport Chain?
A

Glycolysis- cytoplasm
Citric Acid Cycle- Mitochondria
Electron Transport Chain- Mitochondria

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2
Q

What is the initial substrate for glycolysis?

A

1 glucose (6C)

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3
Q

What are the final products of aerobic respiration?

A

ATP

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4
Q

During respiration, does glucose get oxidized or reduced?

A

oxidized

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5
Q

Which process directly uses O2?

A

glycolysis
Citric acid cycle
electron transport

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6
Q

What is the overall equation for glucose oxidation?

A

C6H12O6 + 6CO2 -> 6CO2 + 6H2O + 32 ATP

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7
Q

Why would it be a baad idea to transfer electrons directly from the glucose molecule to oxygen?

A

No energy could be harvested if the electrons were passed directly from glucose to O2.

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8
Q

What is cellular work?

A

cellular work is work done by the cell that requires the input of energy, typically in the form of ATP. (Work that requires ATP).

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9
Q

What are examples of cellular work?

A

Active transport of molecules (transport), the build up of proteins from amino acids (chemical), and muscle contraction (mechanical)

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10
Q

what is cellular work not associated with?

A

work in which energy is given off (ie. breakdown of starch into simple sugars by amylase)

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11
Q

Glycolysis starts with and ends with what?

A

starts with 1 glucose

ends with 2 pyruvate and a net gain of 2 ATP

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12
Q

Pyruvate Oxidization starts and ends with what?

A

starts with 2 pyruvate

ends with 2NADH, 2 Acetyl Co- A’s and 2 CO2 are released.

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13
Q

The Citric Acid Cycle starts with and ends with what?

A

Starts with 2 Acetyl-CoA

ends with 1 ATP, 3 NADH, 1 FADH2 per cycle = 2 ATP, 6NADH, 2FAHD2 no carbon left

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14
Q

The Electron transport chain starts and ends with

A

Starts with 10 NADH, 2FADH2 and 6O2

Ends with 28 ATP+4 from substrate level phosphorylation +32 ATP and 6 H2O

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15
Q

Why is hydrolysis of the terminal phosphate group of the terminal phosphate group from the ATP molecule a favourable process? ( ATP -> ADP + Pi)

A
  • Energy is released because more favourable interactions can occur.
  • The relief of the negative charge repulsion: ATP contains a lot of negative charge due to the the phosphate groups (Pi) so removing it decreases the negative charge.
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16
Q

What happens during a redox equation? give examples?

A

during a redox reaction, electrons are transferred from one molecule to another. When a molecule is reduced it gains electrons, when a molecule is oxidized it loses electrons.

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17
Q

What is the difference between complete and partial electron transfers in redox reactions?

A

complete electron transfers occur when an electron is completely taken from one molecule and possessed by another. A partial electron transfer is when electrons are shared but unequally

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18
Q

How can you estimate the the relative energy content of an organic molecule?

A

Can be estimated by the C-C and C-H bonds present.

the more C-H and C-C bonds the more energy there is.

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19
Q

Organize in highest to lowest energy content a carbon molecule that is: an alcohol, a carboxylic acid, and an aldehyde.

A

alcohol > aldehyde > carboxylic acid

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20
Q

What are the three major pathways of glucose oxidation?

A

i. Glucose- 6 carbon
ii. Pyruvate- 3 carbon atoms ( 2 pyruvate atoms form from glucose)
iii. Acetyl (in acetyl- CoA)- 2 carbon atoms (formed from pyruvate and one carbon is lost as a CO2)

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21
Q

Which form of NAD+ and NADH is ready to accept electrons? give up electrons? considered oxidized? considered reduced?

A
  1. NAD+
  2. NADH
  3. NAD+
  4. NADH
22
Q

which form of FAD/ FADH2 is oxidized/ reduced?

A

FAD is oxidized

FADH2 is reduced

23
Q

per molecule how many electrons do NADH and FADH2 handle during cellular respiration?

A

NADH handles 10 electrons. FADH2 handles 2 electrons

24
Q

Why is the net yield of ATP in glycolysis only 2 ATP per 6C glucose molecules?

A

the net yield remains 2 ATP from phosphate level phosphorylation because 2 ATP are used in the oxidation of glucose to pyruvate.

25
Q

Except for ATP, what other ‘high energy’ molecule is produced in glycolysis?

A

NADH is produced, considered a high energy molecule because it can spontaneously give up its electrons to the electron transport chain.

26
Q

What are the 2 ways of making ATP and the difference between the two?

A

substrate level phosphorylation and oxidative phosphorylation.
Oxidation phosphorylation, oxygen is the is the electron acceptor and forms water. occurs at the end of the electron transport chain in the mitochondria and the pi is free in the matrix.
substrate level phosphorylation doesn’t involve the ETC, and Pi comes from the substrate, occurs during glycolysis in the cytosol

27
Q

What happened to pyruvate in the linking step between glycolysis and the citric acid cycle?

A

pyruvate loses one carbon and two oxygen atoms as CO2, and is attached to a coenzyme A (CoA). This results in the production of NADH

28
Q

How many Carbon Atoms are there in the first intermediate, just after the acetyl group has been added? what is the name of the molecule?

A

Acetyl from Acetyl-CoA is attached to Oxaloacetate in the first step of the citric acid cycle. the resulting molecule, citrate contains 6 carbon atoms

29
Q

How many carbon atoms are there in the last intermediate step of the Krebs cycle, just before the acetyl group is added.

A

oxaloacetate, contains 4 carbon atoms

30
Q

Other than ATP what other high energy molecules are produced in the citric acid cycle?

A

FADH2, NADH

31
Q

Glucose is converted into CO2 during cellular respiration, on which pathways does it happen?

A

CO2 is produced during the conversion of pyruvate into Acetyl-CoA and during the citric acid cycle.

32
Q

Where is the mitochondria is the electron transport chain located?

A

located within the inner membrane of the mitochondria

33
Q

How are electron carrying complexes organized in the ETC: how is electronegativity ordered?

A

arranged in order of increasing electronegativity.

34
Q

What is the function of oxygen in the ETC?

A

acts as the final (terminal) electron acceptor in the ETC. Oxygen is extremely electronegative and does not give its electrons up easily, as oxygen accepts electrons, it is converted into water.

35
Q

Is Complex I of the ETC more or less electronegative than NADH?

A

Complex 1 must be more electronegative than NADH because it has to be able to take electrons from NADH.

36
Q

What does it mean that NADH and FADH2 are ‘re-oxidized’ by the ETC?

A

During glycolysis and the citric acid cycle, NAD+ and FAD are reduced to NADH and FADH2 respectively. Thus, during the ETC, they are re-oxidized back to NAD+ and FAD.

37
Q

Where along the ETC does FADH2 drop off its electrons?

A

FADH2 drops its electrons off at complex II

38
Q

Via which complexes and in which order do electrons travel from NADH to oxygen?

A

NADH > Complex I > Coenzyme Q > Complex III > Cytochrome C > Complex IV > O2

39
Q

Via which complexes and in which order do electrons travel from FADH2 to oxygen?

A

FADH2 > Complex II > Coenzyme Q > Complex III > Cytochrome C > Complex IV > O2

40
Q

Is complex II a proton pump?

A

No protons are pumped into the mitochondrial inter membrane space by complex II. However, complex II is where FADH2 drops off its electrons.

41
Q

Are protons (H+) pumped into, or out of , the mitochondria matrix during electron transport?

A

electrons are pumped out of the mitochondrial matrix and into the inter membrane space.

42
Q

What is the dual nature of the H+ gradient across the inner mitochondrial membrane?

A

There is a lot more H+ in the inter membrane space compared to the matrix resulting the the concentration gradient. Since Protons are charged there is also a electrical gradient. together these allow for H+ to re- enter the matrix.

43
Q

Why does it take energy from the “ falling/ dropping” of electrons through the ETC to pump H+ against its concentration gradient?

A

Molecules like to be evenly distributed and this will spontaneously occur. due to the gradient, it takes energy to pump H+ up the gradient an area of high concentration this energy comes from the ETC.

44
Q

Explain diffusion of H+ away from an area of concentration

A

When there is a concentration gradient, molecules will spontaneously so that the concentrations are the same.

45
Q

Do H+ move toward the ATP synthase and through the pore back into the matrix in a directed manner? or are they moving randomly and some just happen to take the path through the synthase so that they can become an ATP molecule?

A

H+ move randomly and ATP synthase is the only route through which H+ can pass through. H+ are unable to travel through the inner membrane by themselves because the membrane is hydrophobic and H+ are charged.

46
Q

Imagine an ADP molecule inside the mitochondrial matrix. How does it manage to find an ATP synthase so that it can become an ATP molecule?

A

ADP binds to an area of the ATP synthase as it is turned into ATP. The binding between ADP and the ATP synthase is favourable; however, ADP movement is random.

47
Q

Does FADH2 oxidization produce as much ATP as does NADH oxidation?

A

FADH2 does not produce as much ATP as NADH. FADH2 drops its electrons off at complex II which isn’t a proton pump and NADH drops its electrons off at complex I, which is a proton pump. the amount of protons is proportional to the amount of ATP generated, FADH2 generates less ATP.

48
Q

If we could manufacture a molecular channel that allowed H+ to diffuse back into the matrix without having to go through the ATP synthase pore, what would that do to 1) the concentration gradient of H+ across the inner membrane? 2) the number of ATP molecules that would be compared to during normal conditions?

A

1) The pore would lessen the concentration gradient because H+ would easily flow into the matrix.
2) this results in less ATP production since not all H+ would go through ATP synthase.

49
Q

What is the effect of oxygen atoms picking up two H+s each from the matrix when H2O forms at the end of the ETC?

A

O2 is the final electron acceptor in the ETC. by taking up protons and electrons making H2O, this allows the ETC to always continue and further adds to the electrochemical gradient across the inner membrane. Without O2 the ETC will stop.

50
Q

In which pathway/process does the bulk of the ATP produced during cellular respiration occur from?

A

almost all ATP is produced during oxidative phosphorylation. Oxidative Phosphorylation is the combination of ETC and ATP synthase.

51
Q

What would happen in your cells if your oxygen supply was cut off?

A

The ETC would stop since there would be no O2 and nowhere for the electrons to end up. Eventually the Krebs cycle would stop since all NAD+ would be in the form of NADH since there would be no place for NADH to drop its electrons (same for FADH2)

bio 123 lab exam #2 (4 decks)

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