Chapter 7 - How Cells Harvest Energy

Question 1

proton

Answer 1

Positively-charged particle of an atom - H+

Question 2

NAD+

Answer 2

• nicotinamide adenosine dinucleotide
• one of the most important electron (e-) acceptor/carriers
• a cofactor that accepts a pair of e- and a proton (H) to create NADH
• composed of two nucleotides bound together by the phosphates

Question 3

NADH

Answer 3

• NAD+ that has accepted 2 e- and one proton

* Reaction is reversible: can release 2 e- and 1 proton to become NAD+ again

Question 4

FADH2

Answer 4

• FAD that has accepted 2 e-

* Bound to its enzyme in the inner mitochondrial membrane, so only releases e- to the electron transport chain.

Question 5

G-3-P

Answer 5

• Step 4/5 product in glycolysis.

Question 6

Krebs Cycle (summary description and location)

Answer 6

• 9-step process to reduce the acetyl group from Pyruvate Oxidation
• Occurs in the matrix of the mitochondria
• Otherwise known as the citric acid cycle
• When the cell’s ATP concentration is high, the process shuts down and acetyl-CoA is channeled into fat synthesis.

Question 7

Glycolysis (definition/description)

Answer 7

• The break-down of glucose in a cell for metabolism
• E- of C-H bonds are stripped off in a series of reactions (including the Krebs cycle)
• Occurs in the cytoplasm

Question 8

cytoplasm

Answer 8

Material inside a cell, not including the nucleus.

Question 9

oxaloacetate

Answer 9

• “Feeder” molecule (4-carbon) that reacts with acetyl-CoA to start the Krebs Cycle
• Also the Step 9 product of the Krebs Cycle

Question 10

alpha-ketoglutarate

Answer 10

Step 4 product of the Krebs Cycle, a 5-carbon molecule

Question 11

acetyl-CoA

Answer 11

• The end product of Pyruvate Oxidation
• Feeds the Krebs Cycle
• consists of 2 carbons from pyruvate attached to coenzyme A

Question 12

citric acid

Answer 12

• Step 1 product of the Krebs Cycle, a 6-carbon molecule

Question 13

electron transport system

Answer 13

• Series of e- carriers to store energy from oxidation reactions
• Located in the inner membrane of the mitochondrion.
• Electrons from NADH and FADH2 are transferred from complex to complex, with some e- energy lost at each transfer, used to pump H+ out of matrix to inter-membrane space.

Question 14

fumarate

Answer 14

Step 7 product of the Krebs Cycle, a 4-carbon molecule

Question 15

malate

Answer 15

Step 8 product of the Krebs Cycle, a 4-carbon molecule

Question 16

succinate

Answer 16

Step 6 product of the Krebs Cycle, a 4-carbon molecule

Question 17

succinyl-CoA

Answer 17

Step 5 product of the Krebs Cycle, a 4-carbon molecule

Question 18

isocitrate

Answer 18

Step 2/3 product of the Krebs Cycle, a 6-carbon molecule

Question 19

aerobic

Answer 19

involving oxygen (final electron acceptor is O)

Question 20

anaerobic

Answer 20

not involving oxygen (final electron acceptor is an inorganic molecule other than O)

Question 21

pyruvate

Answer 21

• Step 10 product of glycolysis.
• The further fate of pyruvate depends on oxygen availability:
  
  • When oxygen is present, pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle
  • Without oxygen, pyruvate is reduced in order to oxidize NADH back to NAD+

Question 22

glucose 6-phosphate

Answer 22

• Step 1 product of glycolysis

glucose has gained a phosphate from ATP

Question 23

fructose 6-phosphate

Answer 23

• Step 2 product of glycolysis

glucose 6-phosphate has been reorganized

Question 24

citric acid cycle

Answer 24

Also known as the Krebs Cycle

Question 25

fructose 1,6-biphosphate

Answer 25

* Step 3 product of glycolysis

Question 26

substrate level phosphorylation

Answer 26

* The creation of ATP from ADP by transferring a phosphate group from another molecule (Endergonic, enzyme-facilitated reaction where PEP and ADP bind to an enzyme's active sites and a phosphate group is transferred from PEP to ADP.)

Question 27

ATP synthase

Answer 27

* An enzyme that facilitates the synthesis of ATP through oxidative phosphorylation (a second method to substrate-level - energy to transfer the phosphate comes from a proton gradient). * A membrane-bound enzyme that uses the energy of the proton gradient to synthesize ATP from ADP + Pi

Question 28

cellular respiration

Answer 28

The process by which energy is harvested through the oxidation of organic compounds, extracting energy from the chemical bonds.

Question 29

The final e- acceptor in aerobic respiration

Answer 29

Oxygen

Question 30

1,3-Biphosphoglycerate (BPG)

Answer 30

* Step 6 product of glycolysis.

Question 31

3-Phosphoglycerate (3PG)

Answer 31

* Step 7 product of glycolysis.

Question 32

2-Phosphoglycerate (2PG)

Answer 32

* Step 8 product of glycolysis.

Question 33

Phosphoenolpyruvate (PEP)

Answer 33

* Step 9 product of glycolysis.

Question 34

Glycolysis Steps

Answer 34

* Step 1: Phosphate group added to glucose by ATP (to ADP). Produces Glucose 6-phosphate * Step 2: Rearrange Glucose 6-phosphate into Fructose 6-phosphate. Produces Fructose 6-phosphate * Step 3: Phosphate group added to Fructose 6-phosphate by ATP (to ADP). Produces Fructose 1,6-biphosphate * Step 4/5: Fructose 1,6-biphosphate is split into two 3-carbon molecules. Produces one G3P and one that is converted into G3P in a second reaction. * Step 6: Two G3P molecules are each oxidized by NAD+ and a P-group added. Produces 2 NADH and 2 BPG. * Step 7: One phosphate group removed from each BPG by ADP. Produces two ATP and two 3PG. * Step 8: Two 3PG molecules rearranged into two 2PG. * Step 9: Dehydration reaction on two molecules of 2PG. Produces 2 molecules of water and two PEP. * Step 10: One phosphate group removed from each of two molecules of PEP by ADP. Produces two ATP and two Pyruvate.

Question 35

Phosphorylation

Answer 35

Chemical process to add a phosphate group to an organic molecule.

Question 36

Glycolysis: summary of 1st 5 reactions and 2nd 5 reations

Answer 36

* 1st 5: Convert a molecule of glucose into two molecules of G3P. * 2nd 5: Convert two molecules of G3P into two molecules of pyruvate.

Question 37

Krebs Cycle output

Answer 37

* 2 CO2 * 1 ATP * 3 NADH (3 pairs of e-) * 1 FADH2 (1 pair of e-)

Question 38

Krebs Cycle steps

Answer 38

* Step 1: (Condensation) Oxaloacetate reacts with acetyl-CoA to produce citrate. * Steps 2/3: (Isomerization) 2-step process to rearrange citrate into an isomer isocitrate. * Step 4: (1st Oxidation) Isocitrate is oxidized, producing alpha-ketoglutarate, one CO2, and one NADH. * Step 5: (2nd Oxidation) alpha-ketoglutarate is oxidized, producing succinyl-CoA, one CO2, and one NADH. * Step 6: (Substrate-level Phosphorylation) Succinyl-CoA is cleaved into two molecules and the energy released bonds a phosphate to GDP, which releases it to ADP, producing succinate and one ATP. * Step 7 (3rd Oxidation) Succinate is oxidized, producing fumarate and one FADH2. * Step 8/9 (Regeneration of Oxaloacetate) Fumarate accepts a water molecule, turning into malate, which is then oxidized, producing oxaloacetate one NADH.

Question 39

fermentation

Answer 39

* Occurs when oxygen is not available * ATP must be produced by glycolysis * Final electron acceptor is an organic molecule

Question 40

Reduces organic molecules in order to regenerate NAD+

Answer 40

fermentation

Question 41

ethanol fermentation

Answer 41

* occurs in yeast | * CO2, ethanol, and NAD+ are produced

Question 42

lactic acid fermentation

Answer 42

* occurs in animal cells (especially muscles) | * electrons are transferred from NADH to pyruvate to produce lactic acid

Question 43

matrix

Answer 43

The inner-mitochondrial space, inside the inner membrane.

Question 44

cristae

Answer 44

The folds of the inner membrane layer of the mitochondrion, creating many layers.

Question 45

lactate

Answer 45

Ionized form of lactic acid

Question 46

alcohol

Answer 46

A reduced organic compound through fermentation.