Chapter 7 - How Cells Harvest Energy Flashcards Preview

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Flashcards in Chapter 7 - How Cells Harvest Energy Deck (46):
1

proton

Positively-charged particle of an atom - H+

2

NAD+

* 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

3

NADH

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

4

FADH2

* FAD that has accepted 2 e-
* Bound to its enzyme in the inner mitochondrial membrane, so only releases e- to the electron transport chain.

5

G-3-P

* Step 4/5 product in glycolysis.

6

Krebs Cycle (summary description and location)

* 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.

7

Glycolysis (definition/description)

* 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

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cytoplasm

Material inside a cell, not including the nucleus.

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oxaloacetate

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

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alpha-ketoglutarate

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

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acetyl-CoA

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

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citric acid

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

13

electron transport system

* 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.

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fumarate

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

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malate

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

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succinate

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

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succinyl-CoA

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

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isocitrate

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

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aerobic

involving oxygen (final electron acceptor is O)

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anaerobic

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

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pyruvate

* 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+

22

glucose 6-phosphate

* Step 1 product of glycolysis
(glucose has gained a phosphate from ATP)

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fructose 6-phosphate

* Step 2 product of glycolysis
(glucose 6-phosphate has been reorganized)

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citric acid cycle

Also known as the Krebs Cycle

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fructose 1,6-biphosphate

* Step 3 product of glycolysis

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substrate level phosphorylation

* 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.)

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ATP synthase

* 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

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cellular respiration

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

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The final e- acceptor in aerobic respiration

Oxygen

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1,3-Biphosphoglycerate (BPG)

* Step 6 product of glycolysis.

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3-Phosphoglycerate (3PG)

* Step 7 product of glycolysis.

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2-Phosphoglycerate (2PG)

* Step 8 product of glycolysis.

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Phosphoenolpyruvate (PEP)

* Step 9 product of glycolysis.

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Glycolysis Steps

* 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.

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Phosphorylation

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

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

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

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Krebs Cycle output

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

38

Krebs Cycle steps

* 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.

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fermentation

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

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Reduces organic molecules in order to regenerate NAD+

fermentation

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ethanol fermentation

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

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lactic acid fermentation

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

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matrix

The inner-mitochondrial space, inside the inner membrane.

44

cristae

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

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lactate

Ionized form of lactic acid

46

alcohol

A reduced organic compound through fermentation.