Biology Chapter 7

aerobic respiration

From start to finish, the process of aerobic respiration produces a net yield of 36 ATP molecules for every molecule of glucose.

acetyl-CoA Molecule

made up of a 2-carbon acetyl group attached to coenzyme A. During cellular respiration, the acetyl group enters the citric acid cycle for further breakdown.

Alchohol Fermentation

produces alcohol and carbon dioxide from glucose when oxygen is not available

preparatory (prep) reaction:

takes place in the matrix of mitochondria. Pyruvate is broken down to a 2-carbon acetyl group carried by coenzyme A (CoA). Oxidation of pyruvate yields not only NADH but also CO2.

How much ATP is produced from metabolism?

2 ATP from glycolysis 2 ATP from the citric acid cycle 32 ATP from the electron transport chain

Fermentation

A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

lactic acid fermentation

A series of anaerobic chemical reactions using pyruvic acid that supplies energy when oxygen is scarce

The preparatory reaction and the citric acid cycle.

Each acetyl-CoA from the preparatory reaction enters the citric acid cycle. The net result of one turn of this cycle of reactions is the oxidation of the acetyl group to two CO2 and the formation of three NADH and one FADH2. Substrate-level ATP synthesis occurs, and the result is one ATP. For each glucose, the citric acid cycle turns twice, doubling each of these amounts.

There are four phases to cellular respiration:

Glycolysis, preparatory (prep) reaction , citric acid cycle,electron transport chain

What is the net gain of ATP from glycolysis?

Notice if that 2 ATP are used to get started, and 4 ATP are produced. Therefore, there is a net gain of 2 ATP from glycolysis

Energy-Harvesting Steps

Oxidation of G3P results in NADH synthesis Additional chemical changes lead to direct substrate-level phosphorylation, formation of 4 ATP.

electron transport chain:

Passage of electrons along a series of electron carriers from a higher to lower energy levels; the energy released is used to synthesize ATP.

preparatory reaction

Reaction that oxidizes pyruvate with the release of carbon dioxide; results in acetyl CoA and connects glycolysis to the citric acid cycle.

substrate-level ATP synthesis

Process in which ATP is formed by transferring a phosphate from a metabolic substrate to ADP.

cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

Pyruvate is oxidized, and a CO2 molecule is given off. This is part of the CO2 we breathe out. NAD+ accepts electrons and hydrogen ions, forming NADH. The product, a 2-carbon acetyl group, is attached to coenzyme A (CoA), forming acetyl-CoA.

Therefore, Per glucose molecule, the outputs are two CO2, two NADH, and two acetyl-CoA.

Energy-Investment Step

Two ATP are used to activate glucose Glucose splits into two G3P molecules

Oxidation of substrates is

a fundamental part of cellular respiration.

citric acid cycle:

also takes place in the matrix of mitochondria. As oxidation occurs, NADH and FADH2 result and more CO2 is released. The citric acid cycle is able to produce two ATP per glucose molecule.

oxidation in cellular respiration

amounts to removing hydrogen atoms from glucose. Glucose, in turn, is broken down to release energy.

ATP molecules are produced during

cellular respiration by the breakdown of organic molecules, primarily the carbohydrate glucose, with the participation of the mitochondria within eukaryotic cells.

the electron transport chain

series of electron carrier proteins that shuttle high-energy electrons during ATP-generating reactions

Glycolysis

the first phase in the breakdown of glucose, takes place in the cytoplasm outside the mitochondria. A metabolic process that breaks down carbohydrates and sugars through a series of reactions to either pyruvic acid or lactic acid and release energy for the body in the form of ATP

citric acid cycle

the third phase of cellular respiration is the citric acid cycle also called the Krebs cycle. During this phase, the acetyl group is oxidized, releasing more carbon dioxide. NAD+ and FAD accept hydrogen atoms to produce NADH and FADH2. Substrate-level ATP synthesis now occurs, producing ATP.

Glycolysis:

which occurs in the cytoplasm of the cell, is the breakdown of glucose to two molecules of pyruvate. Energy is invested to activate glucose, two ATP are gained, and oxidation results in NADH, which will be used later for additional ATP production.