chapter 7 Flashcards

- electrons are moved up and down an electron transport system

- energy that is given off by their movement is used to pump protons to one side of the membrane

- an electrochemical gradient builds up and the protons want to come back across the membrane

- the protons are allowed back across

- short for oxidization/reduction reactions

- when a molecule loses an electron, it just got oxidized

- when a molecule gains an electron, it just got reduced

- one cannot occur without the other happening simultaneously

- if you set up a string of these reactions, it is called an electron transport system

H+ = proton

NADH - electron and hydrogen carrier (taxi cab)

• When the “taxi” is empty = NAD+

• When the “taxi” is full = NADH

FADH2 - electron and hydrogen carrier (taxi cab)

• When the “taxi” is empty = FAD+

• When the “taxi” is full = FADH2

• Evolved around 3.8 billion years ago

• Anaerobic

• Purpose was to create ATP

• Occurs in the cytoplasm of all living cells

• 10 steps, each requiring a different enzyme

• Produces ATP by substrate-level phosphorylation

• ADP gets a P from a phosphate-bearing intermediate

• Begins with the oxidation of pyruvate

• Oxidative decarboxylation - every time this occurs, a CO2 is produced, as well as an NADH

• Is a cycle, so intermediates are regenerated.

• Chemiosmosis occurs!

• Most of the ATP is made here.

• Electron and H+ carriers “drive” electrons and H+ to the electron transport system.

• Electrons are passed down the electron transport chain, and H+ are pumped into the intermembrane space. They build up there, and come back into the matrix via ATP synthase. ATP is made.

• Oxygen is the final electron acceptor. It accepts electrons and H+ and 6 H2Os are produced.

• Harvests chemical energy without using either oxygen or an electron transport system

• An extension of glycolysis that allows continuous generation of ATP by the substrate-level phosphorylation of glycolysis

• Under aerobic conditions, NAD+ is recycled from NADH by the transfer of electrons to the electron transport system.

• An anaerobic alternative is to transfer electrons from NADH to pyruvate, the end product of glycolysis.

• Pyruvate is converted to ethanol in 2 steps.

• The first step releases carbon dioxide from the pyruvate, which is converted to the 2 C acetate.

• In the second step, acetate is reduced by NADH to form ethanol.

• This regenerates the supply of NAD+ needed for glycolysis.

• Bacteria and yeast (beer, wine, etc.)

• Pyruvate is reduced directly by NADH to form lactate as an end product, with no release of CO2.

• Fungi, bacteria (cheese, yogurt)
• Human muscle cells make ATP by lactic acid fermentation when oxygen is scarce.

Oxygen

Carbon Dioxide

-Glucose

-oxygen

C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + ATP

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