Chapter 7: How Cells Release Chemical Energy
When ____________ is broken down in the cell, the energy stored in the carbon bonds
are released and transferred to____________
Two main mechanisms by which organisms break down sugars to make ATP:
 ________________________
 ____________
________________________: oxygen requiring metabolic pathway that breaks down
sugars to make ATP
 Requires ____________ to break down ____________ to make ____________
 Main ____________________________________in nearly all eukaryotes and
some bacteria
 The three stages of aerobic respiration:
o ____________: linear pathway that occurs in the cytoplasm; net yield is 2
ATP
o ________________________: cyclic pathway that occurs in the
mitochondria; net yield is 2 ATP
o ____________________________________: electron transfer chain
located in the mitochondrial plasma membrane; net yield is 32 ATP
 Final electron acceptor is ____________ which forms
____________
____________: sugar breakdown pathway that does not require oxygen to make ATP
 Like aerobic respiration, fermentation begins with ____________ in cytoplasm
 Unlike aerobic respiration, fermentation occurs entirely in cytoplasm, and does not
include ____________________________________
 Net yield is two ATP, which provides enough ATP to sustain many single-celled
species
 Final electron acceptor is an ________________________ (responsible for the
formation of ethanol)
First stage of aerobic respiration is ____________
 Occurs in the____________
 Series of reactions that begin the ____________________________________of
aerobic respiration and fermentation
 Converts one ________________________________________________ (such as
glucose) into two molecules of ____________: an organic compound with a
three- carbon backbone
Steps of glycolysis:
 Glycolysis starts with a ____________________________________ (glucose)
 A phosphate group is transferred from____________to glucose, forming glucose-6phosphate
 Glucose-6-phosphate accepts a phosphate group from another ____________
forming fructose-1,6-biphosphate which splits to form two____________
(phosphoglyceraldehyde)
 Each PGAL receives a second phosphate group, and each gives up two electrons
and a hydrogen ions to form two molecules of____________ (phosphoglycerate)
o The electrons and hydrogen ions are accepted by two NAD+, forming
____________ (required for third step of aerobic respiration)
 A phosphate group is transferred from each ____________ to ADP forming two
____________ and two ____________ (phosphoenolpyruvic acid) molecules
 A phosphate group is transferred from each____________to ADP forming two
____________ and two____________molecules
o The direct transfer of a phosphate group from a substrate to ADP is called
____________________________________
Glycolysis summary:
 Net yield of glycolysis is ______________________________________________
o Total of four ATP produced, but two ATP are used during glycolysis
 ________________________
 ________________________
Second stage of aerobic respiration includes two sets of reactions:
____________________________________and the ________________________
 Occurs inside the ____________
 Completely breaks down the ____________ produced during glycolysis into
____________with the production of ____________
Steps of Acetyl–CoA Formation:
 ____________ from glycolysis is transported into the _______________________
 Pyruvate is split into ______and a two-carbon ____________________(—COCH3)
o CO2 diffuses out of the cell
o Acetyl group combines with ________________________ (CoA),
forming ________________________
o Electrons and hydrogen ions released by the reaction combine with NAD+
forming ____________
Steps of the Kreb’s Cycle:
 ________________________enters the Kreb’s cycle
 One carbon atom from acetyl-CoA is transferred to _______ forming ___________
o ________________________is regenerated
 ________________________are removed from two intermediates forming
____________
o ____________form and departs the cell
o ____________is reduced forming NADH
o ____________forms by substrate-level phosphorylation
 ____________ is converted to ____________
o FAD+ (flavin adenine dinucleotide) is reduced to ____________and
NAD+ is reduced to ____________
o ____________ are delivered to the third stage of aerobic respiration
Acetyl-CoA Formation and Kreb’s Cycle Summary: each molecule of pyruvate that
enters the second stage of aerobic respiration produces
o ____________: ____________from acetyl-CoA formation and ____________from
Kreb’s cycle
o ____________from Kreb’s cycle
o _______: _________from acetyl-CoA formation and _________from Kreb’s cycle
o ____________from Kreb’s cycle
In total the ____________________________________that enter second stage of aerobic
respiration produces
o _________: ________from acetyl-CoA formation and ________from Kreb’s cycle
o ____________from Kreb’s cycle
o _________: _________from acetyl-CoA formation and _______from Kreb’s cycle
o ____________from Kreb’s cycle
Third stage of aerobic respiration is ____________________________________
 Occurs in the inner ____________
 Uses the coenzymes (____________and ____________) produced in the first two
stages of aerobic respiration to produce a ___________________________which
is utilized to create ATP via ________________________
 ____________ accepts electron at the end of the mitochondrial electron transfer
chains
Steps of electron transfer phosphorylation:
 ____________ and ____________delivers e- and H+ to the electron transfer chain
 e- moves down the chain releasing energy with each step which is used
______________________________________ across the inner membrane from
matrix to intermembrane space forming a ________________________
 H+ passively flow back into the matrix
through________________________driving the formation of ATP from ADP
and Pi
 ____________ accepts e- at the end of the electron transfer chain and combine with
H+ to form ____________
Electron transfer phosphorylation summary:
 ________________________
 ________________________
Total ATP summary for aerobic respiration:
1 glucose produces…… ____________from glycolysis
____________from Kreb’s cycle
____________from electron transfer phosphorylation
TOTAL: ____________
________________________: Fermentation
 Begins like ____________, same set of reactions in the ____________
 Final steps of fermentation occurs in the cytoplasm and does not require
____________
o ____________ is not fully broken down to ____________
o Electrons do not move through
____________________________________, so no additional ATP forms
o ____________is regenerated, allowing glycolysis to continue
Two fermentation pathways:
 ________________________: anaerobic sugar breakdown pathway that produces
ATP, CO2, and ethanol
 ________________________: anaerobic sugar breakdown pathway that produces
ATP and lactate
Steps of alcoholic fermentation:
 3-carbon ____________ is split into ________________________and 2-carbon
________________________
 Electrons and hydrogen are transferred from ____________ to the acetaldehyde,
forming ____________and ____________
Steps of lactate fermentation:
 Electrons and hydrogen ions carried by ____________ are transferred directly to
____________
 ____________ is converted to 3-carbon ____________
 ____________is converted to ____________
Animal muscle cells carry out aerobic respiration and/or lactate fermentation
 ____________________________________: many mitochondria and myoglobin;
produce ATP mainly by aerobic respiration which sustains prolonged activity
 ____________________________________: contain few mitochondria and no
myoglobin; most ATP produced by lactate fermentation which is useful for quick,
strenuous activities