Biology 20: Unit C
Textbook: Pages 202-233
A series of chemical reactions that breaks down
glucose to release energy
 The energy is then stored in a molecule that the
cell can use to do work
 This molecule is called ATP
 Cellular respiration takes place in all Eukaryotic
cells

Has the same format as a combustion reaction
 Is different from a combustion reaction because:
 It is a slower reaction
 The energy released in steps (otherwise
spontaneous combustion would be the result)
 The energy released is stored in ATP
 The cell then uses ATP energy to carry out
reactions that require energy
 How does ATP store energy?

 Each
ATP molecule holds about 1% of the energy
of a glucose molecule
 ~36% of the energy of glucose is stored as ATP
after cell respiration
 ~64% is lost as heat
 This heat maintains body temperature
High
energy
ATP formation
ATP
reactants
oxidation reduction
reaction
products
Low
energy
energy
from
reaction
ADP + Pi
 Refer
to chemical reactions where electrons are
transferred
 Oxidation = loss of electrons (LEO)

Na
Na+ + e-
 Reduction

Na+ + e-
 In
(GER)
Na
biological systems energy is associated with the
movement of electrons
 Electrons can be pulled away from a molecule
 Hydrogen atoms are usually lost from a molecule
during oxidation
 Hydrogen atoms are usually gained by a molecule
during reduction
Is an important electron carrier
 NAD+ can attract electrons
 NAD+ + 2e- + H+
NADH

NAD+ is reduced
 NADH is an electron carrier
 NADH can also lose electrons
 NADH
NAD+ + 2e- + H+

 NADH
is oxidized
 Occurs when NADH is in contact with a molecule
that has a strong attraction for electrons
 NAD+ Is recycled
1.
Glycolysis
 in cytoplasm
Transition Step
 In mitrochondria
2.
3.
Kreb’s cycle
 in matrix of mitochondria
4.
Electron Transport Chain and
Chemiosmosis
 inner membrane of mitochondria
Remember
This !!!
Remember
This !!!
Energy, Cells, and ATP
Label the diagram
choosing from the
following words or
phrases:
•Transport protein
•ATP
•ADP
•P X 4
•Phosphorylated
•Protein releases solute
outside cell
•Phosphate detaches
from protein
Glucose and ATP
Label the diagram
choosing from the
following words or
phrases:
•100 %
•About 40 %
•25 %
•Energy released from
glucose banked in ATP
•Gasoline converted to
movement
•“Burning” glucose in
cellular respiration
•Burning glucose in an
experiment
Cell Anatomy
Identify the plant cell;
identify the animal cell.
Label the diagram
choosing from the
following words or
phrases:
•Mitochondria
•Cytoplasm
Mitochondria Anatomy
Use Nelson page 214
Label the diagram choosing
from the following words or
phrases:
•Inner membrane
•Mitochondrion
•Outer membrane
•Cristae
•Intermembrane space
•Matrix
Takes place in the cytoplasm of
the cell
 A 6-carbon glucose molecule is
split into two molecules of
pyruvate (3 carbons each)
 Is an anaerobic process (does
not require oxygen)
 In glycolysis, two ATP molecules
are needed to start the reaction
 Four ATP molecules are
produced
 There is a net gain of 2 ATP
molecules

Glucose (6C)
2 ATP
2 ADP
4 ADP + P
4 ATP
2 NAD
2 NADH
2 Pyruvate
molecules (3C)
 NADH
(2) molecules are also produced
 Glucose is oxidized
 NAD+ is reduced
Note: Pyruvic acid = Pyruvate
 Pyruvate
enters the next phase of cellular
respiration (transition Step)
 NADH is used in chemiosmosis and electron
transport
 ATP is used by the cell to carry out biological
work
Glycolysis Overview
Animation:
http://www.science.smith.ed
u/departments/Biology/Bio23
1/glycolysis.html
 Before
the Kreb’s cycle begins, pyruvate is
modified
 This takes place in the mitochondria
 One carbon is lost (in the form of CO2) to form an
acetyl molecule
 Acetyl joins to a carrier called coenzyme A to
form acetyl Co-A
 One NADH forms
 Glycolysis


2 ATP per glucose
2 NADH per glucose
 Transition

1 NADH per pyruvate (2 NADH per glucose)
 Per


Step
glucose:
2 ATP
4 NADH




Read Pages 202-212 in your textbook
Complete Practice Problems 1-5 – pages 205, 207
Complete Section 7.1 Questions 1-5 on page 209
Complete Section 7.2 Questions 1-3 on page 212
Glycolysis
Label the diagram choosing
from the following words or
phrases:
•A fuel molecule is
energized, using ATP.
•A redox reaction generates
NADH
•A six – carbon
intermediate splits into two
three – carbon
intermediates.
•ATP and pyruvic acid are
produced
•Glucose
•G3P
•Pyruvic acid
•ATP X 4
Pyruvate Oxidation
Label the diagram choosing
from the following words or
phrases:
•Pyruvic acid
•NADH + H+
•Coenzyme A
•CO2
•Acetyl CoA (acetyl
coenzyme A)
•NAD+
Also called the citric acid cycle
 Takes place in the matrix of the mitochondria
 Starts with Acetyl-CoA (2 per glucose)
 Cycle goes around twice for every glucose molecule
that undergoes glycolysis
 Acetyl-CoA is oxidized, NAD+ and FAD are reduced

2 carbons enter as
acetyl – CoA
 2 carbons leave as CO2
 (3) NAD+ are reduced to
form NADH
 (1) FAD is reduced to
form FADH2
 1 ATP is formed
 NOTE: these numbers
double for a glucose
molecule

Overview animation:
http://www.science.smith.edu/departments/Biology/Bio231/krebs.html
 The
inner membrane of the mitochondria
contain proteins that can carry electrons
 These proteins are called cytochromes
 They take electrons from NADH and FADH2 that
are produced in glycolysis and the Kreb’s cycle
 NAD+
and FAD
are recycled
and can be used
in glycolysis and
Kreb’s cycle
A small amount of energy is released as they are
passed from protein to protein
 This energy is used to move H+ into the
intermembrane space

OXYGEN
Is the final electron acceptor
 Has a stronger attraction for electrons than any of
the proteins in the membrane
 It is reduced to form water
 2 H+ + ½ O2 + 2eH2 0
 What happens to the ETC if there is no O2?
 A lack of oxygen causes the system to back up all
the way to glycolysis because the NADH and FADH2
can’t be recycled

A process that produces
most of the ATP for
cellular respiration
 32 ATP are produced per
glucose in chemiosmosis

Chemiosmosis
requires…

A concentration gradient
of H+ ions
An ATP synthase channel which is found in the
inner membrane of the mitochondria
 Remember that electron transport causes H+ to
build up in the intermembrane space

 H+
ions are not allowed to
diffuse back into the
matrix
 The ATP synthase
channel is the only place
permeable to H+
 As hydrogen flow back
into the matrix from the
intermembrane space
energy is released
 This energy is used to
Animation of ETC:
http://www.science.smi
make ATP
th.edu/departments/Bio
 32 per glucose
logy/Bio231/etc.html
2 ATP from glycolysis
 2 ATP from Kreb’s
 32 ATP from the electron transport and chemiosmosis
 Total = 36 ATP per glucose

A Review of Cellular Respiration:
http://www.toppermost.biz/CellResp.html
 Electron
Transport and ATP Synthesis

http://bcs.whfreeman.com/thelifewire/content/
chp07/0702001.html

http://highered.mcgrawhill.com/olc/dl/120071/bio11.swf
http://www.science.smith.edu/departments/Biol
ogy/Bio231/etc.html
 A Review of Cellular Respiration:
 http://www.toppermost.biz/CellResp.html

Read Pages 213-220 of textbook
 Complete “Practice” problems 1-6, pages 215, 219
 Compete Section 7.3 Questions 1-10 on page 220
 Compete the Workbook supplementary diagrams

 Refers
to respiration without oxygen
 Without oxygen NADH and FADH2 cannot get rid
of their electrons
 This means there is no NAD+ for glycolysis or
Kreb’s cycle
When oxygen levels decrease…
 NADH and FADH2 give their electrons to another
acceptor instead of oxygen
 This allows NAD+ and FAD to be available for
glycolysis (which produces a small amount of
ATP
Anaerobic respiration produces ethanol, and is
called fermentation
 Fermentation has commercial uses: breweries,
bread making, wine making

Anaerobic respiration produces lactic acid
 When cells are not receiving enough oxygen, muscles
become cramped due to a build of lactic acid
 When oxygen becomes available, lactic acid is
converted back into pyruvate
 Pyruvate then continues to Kreb’s cycle
 Anaerobic respiration is useful because it provides a
short burst of energy when oxygen is not available
 However, it can only produce a small amount of ATP
compared with aerobic respiration (2 ATP)

Exercise physiology
 Branch of biology dealing with body’s biological
responses
 Most common question: shortage of energy by
athletes
 Athletic fitness
 Measure of ability of heart, lungs, and
bloodstream to supply O2 to cells of body
 Other factors to athletic fitness:
 Muscular strength, muscular endurance,
flexibility, body composition (ratio of fat to bone
to muscle)

A measure of body’s capacity to generate E required
for physical activity
 Treadmill exercise test is used to measure VO2 max
 10 – 15 minute test
 Animal is forced to move faster and faster on a
treadmill
 Expired air is collected and measured by a
computer
 VO2 max measures:
 Volume of O2 (mL) that cells of body can remove
from bloodstream in 1 minute per kg of body mass
 While body experiences maximum exertion

VO2 max values:
 Average: 35 mL/kg/min.
 Athletes: 70 mL/kg/min.
 VO2 max
 Can be increased with more exercise
 Genetic variation is also a factor
 Decreases with age





Value of exercise intensity at which blood lactic acid
concentration begins to increase sharply
 Exercising beyond threshold may limit duration of
exercise
 Due to pain, muscle stiffness, and fatigue
Athletic training improves blood circulation and
efficiency of O2 delivery to body cells
 Result:
 Decrease in lactic acid production
 Increase in lactic acid threshold
Untrained individuals reach a lactic acid threshold at
60 % VO2 max
Elite athletes reach threshold at or above 80 % VO2
max

Creatine phosphate
 May serve as an E source by donating its
phosphate to ADP
 Occurs naturally in body and many foods
 Athletes consume compound to produce more ATP
in muscles
 Compound may also buffer muscle cells and delay
onset of lactic acid fermentation
 Potential harmful side – effects are possible
 Some
poisons interfere with the electron
transport chain
 Causes death quickly because electron flow
stops, which stops all stages of cellular
respiration
 Examples:
Cyanide
 Hydrogen sulfide

 Read
pages 221 – 228 of your textbook
 Complete “Practice” Problems 1-6, pages
222, 226
 Complete Section 7.4 Questions – Page 228
#’s 1-6, 9
Simplistic View of
Krebs Cycle
Label the diagram choosing
from the following words or
phrases:
•CoA
•NADH
•ATP
•FADH2
Overview of Krebs
Cycle
Label the diagram choosing
from the following words or
phrases:
•Redox reactions generate
FADH2 and NADH
•Acetyl CoA stokes the
furnace.
•NADH, ATP, and CO2 are
generated during redox
reactions
•ATP
•NADH
•FADH2
•Krebs Cycle
Electron Transport
Chain and
Chemiosmosis
Use Nelson page 217
Label the diagram choosing from
the following words or phrases:
•Mitochondria matrix
•NADH
•ATP
•ADP + P
•½ O2 + 2H+
•H2O
•NAD+
Protein complex
•Electron carrier
•H+ X 5
•Electron Transport Chain
•ATP Synthase
Aerobic Respiration
Energy Balance Sheet
Use Nelson page 219
Label the diagram choosing from the
following words or phrases:
•Cytoplasmic fluid
•Glycolysis: glucose  pyruvic acid
•2NADH X 2
•6 NADH
•2 FADH2
•+ 2 ATP X 2
•+ about 34 ATP
•By chemisosmotic phosphorylation
•About 38 ATP
•Krebs Cycle
•Electron Transport Chain and
Chemiosmosis
•Mitochondrion
•Electron shuttle across membranes
•2 Acetyl CoA
Alcohol Fermentation
Use Nelson page 221
Label the diagram choosing from the
following words or phrases:
•Glycolysis
•Glucose
•2 ATP
•2 NADH X 2
•2 pyruvic acid
•2 ethanol
•2 CO2 released
•2 ADP + 2 P
Lactic Acid
Fermentation
Use Nelson page 224
Label the diagram choosing from the
following words or phrases:
•Glycolysis
•Glucose
•2 ATP
•2 NADH X 2
•2 pyruvic acid
•2 lactic acid
•2 ADP + 2 P
Cellular Respiration
and Other Sources of
Energy
Label the diagram choosing from the
following words or phrases:
•Krebs cycle
•ATP
•Electron Transport Chain and
Chemiosmosis
Cellular Respiration
and Biosynthesis
Label the diagram choosing from the
following words or phrases:
•Krebs cycle
•ATP
•Cells, tissues, organisms
Unit C Review

Complete the following to help you prepare for
the upcoming unit final
 Page 232 #1-8, 11-13
 Page 234-235 # 1-10