Cellular Respiration Flashcards by Melanie Chau

Exergonic

Catabolic breakdown of organic molecules- releases energy

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Aerobic respiration

Consumes organic molecules and O2 and yields ATP

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Fermentation

A partial degradation of sugars that occurs without O2 (anaerobic)

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Cellular respiration

Includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration

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The catabolism of glucose free energy change

-686 kcal / mol

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Phosphorylation

Transferring the terminal phosphate group to another molecule

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Transfer of electrons

The transfer (relocation) of electrons during chemical reactions releases energy stored in organic molecules

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Synthesis of ATP

The release energy from the transfer of electrons is used to synthesize ATP

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Oxidation-reduction/redox reaction

Chemical reactions that transfer electrons between reactants

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Oxidation

Substance loses electrons (OIL)

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Reduction

A substance gains electrons (RIG)

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Reducing agent

The electron donor

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Oxidizing agent

The electron receptor

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Enzymes

In cellular respiration, glucose and other organic molecules are broken down in a series of steps- each catalyzed by a specific enzyme

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NAD+

A coenzyme- Electrons from organic compounds are usually first transferred to NAD+

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Electron carriers

NADH and FADH; Hydrogen atoms are stripped from glucose and passed to these electron carriers

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Electron transport chain

NADH passes electrons to the electron transport chain

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Glycolysis

Occurs in the cytoplasm; Breaks down glucose into two molecules of pyruvate

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Citric acid / Krebs cycle

Completes the breakdown of glucose (pyruvate -> CO2)
Oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn

Oxidative phosphorylation

(Powered by redox reactions of the ETC, inorganic P added to ADP) accounts for almost 90% of the ATP generated by cellular respiration

Substrate-level phosphorylation

Phosphate group transferred from a organic substrate to ADP- forms small amount of ATP in glycolysis and the citric acid cycle

Glucose -> ATP

For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to 32 molecules of ATP

Energy investment phase

One of glycolysis major phases (how many put in?)

Energy payoff phase

One of glycolysis major phases (how many released?)

Electron transport chain (ETC)

- Electrons are removed- passed to electron carriers (NADH) and taken to ETC - Citric acid cycle: NADH & FADH2 relay electrons from food to the ETC

Oxygen in glycolysis

Glycolysis occurs whether oxygen is present or not

Oxidation of glucose

If O2 is present pyruvate enters the mitochondrion (in eukaryotic cells) where the oxidation of glucose is completed

Coenzyme A (acetyl CoA)

Before the citric acid (Krebs) cycle can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle

Steps of the citric cycle

[8 steps] - A acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate - The next seven steps decompose the citrate back to oxaloacetate, making the process a cycle

Chemiosmosis couple (ETC -> ATP synthesis)

Following glycolysis and the citric acid cycle, NADH and FADH2 accounts for most energy extracted from food -> electron carrier donate electrons to ETC -> powers ATP synthesis via oxidative phosphorylation

Cristae

The inner membrane of the mitochondrion where ETC is location

Final electron acceptor (ETC)

Carriers alternate reduced and oxidized states until electrons drop free energy and are passed to the final electron acceptor: O2, forming H2O

Cytochromes

Proteins that electrons are passed through (each with an iron atom) to O2

Mitochondrial matrix

Pumps H+ due to proteins from electron transfer in the ETC to the intermembrane space

ATP synthase

Protein that H+ passes through after moving back across the membrane

Phosphorylation

ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP

Chemiosmosis

The use of energy in a H+ gradient to drive cellular work

Proton-motive force

The H+ gradient, energy stored in a H+ gradient across a membrane couples the redox reactions of ETC -> ATP synthesis

Cellular respiration sequence

Glucose -> NADH -> electron transport chain -> proton-motive force -> ATP

Alcohol fermentation

Pyruvate is converted to ethanol in two steps - First releasing CO2 Alcohol fermentation by yeast is used in brewing, winemaking, and baking

Lactic acid fermentation

Pyruvate is reduced to NADH, forming lactate as an end product, with no release of CO2

Human muscle cells

Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce

Obligate anaerobes

Carry out fermentation or anaerobic respiration and cannot survive in the presence of O2

Facultative anaerobes

Yeast and many bacteria, meaning that they can survive using either fermentation or cellular respiration

Amino acids

Proteins must be digested to amino acids; amino groups can feed glycolysis or the citric acid cycle

Glycerol

Used in glycolysis from fats that are digested

Fatty acids

Used in generating acetyl CoA from fats that are digested