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Cell respiration and metabolism

Terms in this set (85)

Metabolism
is the complete set of chemical reactions that occur in living cells. These processes are the basis of life, allowing cells to grow and reproduce, maintain their structures, and respond to their environments.
The chemical reactions of metabolism
are organized into metabolic pathways, in which one chemical is transformed into another by a sequence of enzymes.
Enzymes allow the regulation of metabolic pathways
in response to changes in the cell's environment or signals from other cells.
Catabolic reactions
release energy, usually by the breakdown of larger organic molecules into smaller molecules.
The catabolic reactions that break down glucose, fatty acids, and amino acids
serve as the primary sources of energy for the synthesis of ATP. this means that some of the chemical-bond energy in glucose is transferred to the chemical bond energy in ATP. Since energy transfers can never be 100% efficient, some of the chemical-bond energy from glucose is lost as heat.
Anabolic reactions
require the input of energy and include the synthesis of large energy-storage molecules, including glycogen, fat, and protein.
Aerobic respiration
requires O2 in order to generate ATP. It is the preferred method of pyruvate breakdown from glycolysis & requires that pyruvate enter the mitochondrion to be fully oxidized by the Krebs cycle. The product of this process is energy in the form of ATP by substrate-level phosphorylation, NADH.
The energy transfer involves
oxidation-reduction reactions.
Oxidation of a molecule occurs when
the molecule loses electrons.This must be coupled to the reduction of another atom or molecule, which accepts the electrons.
In the breakdown of glucose
and other molecules for energy, some of electrons initially present in these molecules are transferred to intermediate carriers and then to a final electron acceptor.
When a molecule is completely broken down to carbon dioxide and water within an animal cell,
the final electron acceptor is always an atom of O2. Because of the involvement of O2, the metabolic pathway that converts molecules such as glucose or fatty acid to carbon dioxide and water (transferring some of the energy to ATP) is called aerobic cell respiration.
Glycolysis
is the metabolic pathway by which glucose-a six-carbon sugar is converted into to molecules of pyruvic acid,or pyruvate.
Each pyruvic acid molecule contains
three carbons, three oxygens, and four hydrogens.
Glucose molecule
C6H12O6- can thus be accounted for in the two pyruvic acid molecules.
In glycolysis,
four hydrogen atoms are removed from the intermediates. Each pair of these hydrogen atoms is used to reduce a molecule of NAD. In this process, each pair of hydrogen atoms donates two electrons to NAD, thus reducing it.
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