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Cellular respiration Breaking down sugar in the presence of oxygen (aerobic) to produce ATP.
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9.2 The Process of Cellular Respiration
Lesson Overview 9.2 The Process ofCellular Respiration Cellular
respiration Breaking down sugar in the presence of oxygen (aerobic)
to produce ATP. Glycolysis Summary What happens during the process
of glycolysis?
During glycolysis, 1 molecule of glucose, a 6-carbon compound, is
transformed into 2 molecules of pyruvic acid, a 3-carbon compound.
Glycolysis Cellular respiration begins with glycolysis 1.
Glycolysis occurs in the cytoplasm 2. Reactants = glucose, 2 NAD+,
2 ATP, 3. Products = 2 pyruvates, 2 NADH, 4 ATP (Net 2 ATP), NAD+ =
nicotinamide adenine dinucleotide a co-enzyme necessary for the
reaction to go forward, H+ donator in the electron transport chain
During glycolysis NAD+ is reduced to NADH. Glycolysis Glycolysis is
the first stage of cellular respiration.
Glycolysis means sugar-breaking During glycolysis, glucose (a
6-carbon sugar)is broken down into 2 molecules of the 3-carbon
molecule pyruvic acid. Pyruvic acid is a reactant in the Krebs
cycle. ATP and NADH are produced as part of the process. The
Advantages of Glycolysis
Glycolysis produces ATP very fast, which is an advantage when the
energy demands of the cell suddenly increase. Glycolysis does not
require oxygen, so it can quickly supply energy to cells when
oxygen is unavailable. The Krebs Cycle What happens during the
Krebs cycle?
During the Krebs cycle, pyruvic acid is broken down into carbon
dioxide in a series of energy-extracting reactions. The Krebs Cycle
During the Krebs cycle, the second stage of cellular respiration,
pyruvic acid produced in glycolysis is broken down into carbon
dioxide in a series of energy-extracting reactions. The Krebs cycle
is also known as the citric acid cycle because citric acid is the
first compound formed in this series of reactions. Krebs Cycle
Occurs in the matrix of the mitochondria
Reactants = 2 acetyl CoA, 2 ADP, 6 NAD+, 2 FAD Products = 2 ATP, 6
NADH, 2 FADH2, 4 CO2 For every glucose molecule that starts cell
respiration, 2 pyruvates are formed, forming 2 acetyl CoAs FAD
flavin adenine dinucleotide co-enzyme necessary for the reaction as
well as an electron donor in the electron transport chain During
Krebs cycle both NAD+ & FAD are reduced to NADH & FADH2
respectively Electron Transport and ATP Synthesis
How does the electron transport chain use high-energy electrons
from glycolysis and the Krebs cycle? The electron transport chain
uses the high-energy electrons from glycolysis and the Krebs cycle
to convert ADP into ATP. Electron transport System
Occurs in within the inner membrane of the mitochondria Reactants =
6 NADH, 2 FADH2, 6 O2, ADP Products = approximately 36 38 ATPs, 4
H2O The Totals How much energy does cellular respiration
generate?
Together, glycolysis, the Krebs cycle, and the electron transport
chain release about 36 molecules of ATP per molecule of glucose.
Energy yield from glucose metabolism
Glycolysis 2 ATP Krebs Cycle 2 ATP2 NADH from glycolysis 4 ATP 2
NADH from transition step 6 ATP 6 NADH from Krebs Cycle 18 ATP 2
FADH2 from Krebs Cycle 4 ATP TOTAL 36 ATP Energy Totals In the
presence of oxygen, the complete breakdown of glucose through
cellular respiration results in the production of 36 ATP molecules.
This represents about 36 percent of the total energy of glucose.The
remaining 64 percent is released as heat. Energy Totals The cell
can generate ATP from just about any source, even though weve
modeled it using only glucose.Complex carbohydrates are broken down
into simple sugars like glucose.Lipids and proteins can be broken
down into molecules that enter the Krebs cycle or glycolysis at one
of several places.