Bio 220: Lecture 11

Front 1

In living systems oxidation and reduction reactions are _____.

Back 1

coupled

Front 2

When highly reduced substrates such as glucose are oxidized, the hydrogens (with their electrons) that are lost, must be gained by ____.

Back 2

other chemicals

Front 3

Other chemicals therefore reduced as they gain _____.

Back 3

hydrogens

Front 4

Coenzymes can receive these hydrogens (become reduced) to …

Back 4

make enzymatic reactions work.

Front 5

Same coenzymes will later become oxidized when they donate their hydrogens to allow …

Back 5

other enzymatic reactions to occur.

Front 6

_____ is a highly reduced substrate

Back 6

glucose

Front 7

Glucose has the potential to go through many oxidation reactions yielding _______.

Back 7

much energy

Front 8

Energy is captured in ATP by the process of _____.

Back 8

phosphorylation

Front 9

define: substrate level phosphorylation

Back 9

occur when high energy phosphates are directly transferred from phosphorylated compounds to ADP.

Front 10

Phosphorylations that occur as part of the electron transport chain (system) are known as _____.

Back 10

oxidative phosphorylation

Front 11

Hydrogens that deliver their electrons to the electron transport chain (system) for oxidative phosphorylation are transported on ….

Back 11

reduced coenzymes (NAD and FAD)

Front 12

Reduced coenzymes give up their hydrogens (with their electrons) to ETC compounds and become ____ in the process.

Back 12

oxidized

Front 13

Coenzymes are now free to undergo ____ and pick up hydrogens once again.

Back 13

reduction

Front 14

define: respiration

Back 14

any energy yielding oxidation in which the terminal hydrogen acceptor is an inorganic compound. Gaseous oxygen is not necessarily involved.

Front 15

define: aerobic respiration

Back 15

any energy yielding oxidation in which the terminal hydrogen acceptor is the inorganic compound oxygen. (highest energy yield)

Front 16

define: anaerobic respiration

Back 16

any energy yielding oxidation in which the terminal hydrogen acceptor is an inorganic compound other than oxygen.
• Terminal hydrogen acceptors include compounds such as nitrate (NO₃⁻¹), sulfate (SO₄⁻²) or carbonated (CO₃⁻²)

Front 17

define: fermentation

Back 17

is any energy yielding oxidation in which the terminal hydrogen acceptor is an organic compound.
• This does not require oxygen.
• This is anaerobic
• ETC is not used (lowest energy yield)

Front 18

What are the three major reaction pathways used in the complete oxidation of glucose?

Back 18

1. Glycolysis
2. Krebs Cycle (Citric Acid Cycle or Tricarboxylic Acid Cycle)
3. Electron Transport System or Chain (Cytochrome System)

Front 19

What is the step between Glycolysis and Kreb Cycle?

Back 19

Preparatory or Intermediate Step

Front 20

Enzymatic reactions for ATP production occur on the ______ of prokaryotes.

Back 20

plasma (cell) membrane

Front 21

What are the features of Glycolysis?

Back 21

• net gain of 2 ATPs from substrate level phosphorylation. Actually 2 ATPs are used to prime reactions, but 4 ATPs are actually produced
∙ 2 hydrogen pairs (2H will be used to represent a hydrogen pair) are produced.
• Each 2H is attached to the coenzyme NAD. Therefore, 2 NAD each with a hydrogen pair is produced. The reduced NAD has the potential to carry the 2H to the ETC (later) for ATP production by oxidative phosphorylation
• Glycolysis is anaerobic it does not requre or use oxygen whether oxygen is present or not.
• Glycolysis is a series of 10 separate enzymatic reactions. The 6 carbon glucose is eventually split into two 3 carbon pyruvic acids

Front 22

Intermediate of Preporatory Step

Back 22

• Before enetering the Krebs Cycle, each pyruvic acid must lose one molecule of CO₂ and become a 2 carbon unit (acetyl group). Since 2 pyruvic acids are produced from each glucose that entered glycolysis, 2CO₂'s are produced in this step per glucose. Furthermore, for each pyruvic acid that is converted to an acetyl, a 2H (hydrogen pair) is removed (oxidation reaction) and attached to NAD (becomes reduced). There are 2 pyruvic acids per glucose so 2 NAD's each with a 2H is created per glucose in this preparatory step.
• Each acetyl group is now attached to the coenzyme called CoA to become acetyl CoA. The acetyl CoA delivers the 2 carbon acetyl group to the Kreb's Cycle reactions

Front 23

What are the features of the Kreb's Cycle?

Back 23

• series of biochemical reactions in which the large amount of potential chemical energy stored in acetyl CoA is released in steps. Intermediate compounds in the Kreb's cycle are oxidized and the hydrogens are added to the coenzymes NAD and FAD (they become reduced) along the way. Remember that reduced NAD and FAD will carry the hydrogens along with their electrons to the ETC from ATP production
1. Acetyl CoA delivers its acetyl group (2C) to a 4C compound in the Kreb's Cycle called oxaloacetic acid. Citric Acid is a 6C compound is formed.
2. In step 3, a hydrogen pair (2H) is added to NAD. Also a CO₂ is removed (decarboxylation). The compound now has 5 carbos.
3. In step 4, another 2H is added to NAD and another CO₂ is removed. We now have a 4C compound
4. In step 5, ATP is produced through substrate level phosphorylation
5. In step 6, succinic acid (succinate) is converted to fumaric acid (fumarate). This dehydrogenation reaction added 2H to FAD (thus reducing FAD). FAD like NAD will carry the hydrogen pair to the ETC from ATP production.
6. In step 8, another 2H is added to NAD. The compound oxaloacetic acid is formed and the cycle can be repeated

Front 24

How many times does the Krebs Cycle turn per glucose?

Back 24

twice

Front 25

In the Krebs Cycle, for each glucose, ___ acetyl groups are formed.

Back 25

2

Front 26

define: decarboxylation

Back 26

The removal of CO₂ from an amino acid

Front 27

What step in the Krebs cycle is succinate converted to fumarate?

Back 27

Step 6

Front 28

What is the compound that is formed in Step 8 of the Krebs cycle?

Back 28

oxaloacetic acid