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Cellular Respiration
How Cells Harvest Chemical
Energy
Objectives
• Define cellular respiration
• Describe the major events in glycolysis
• Compare and contrast lactic acid
fermentation and alcoholic fermentation
• Summarize the events of the Krebs cycle
and the electron transport chain
• Relate aerobic respiration to the structure
of a mitochondrion
Define Vocabulary
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Acetyl CoA
Aerobic respiration
Alcoholic fermentation
Anaerobic
Cellular respiration
Citric acid
Fermentation
Glycolysis
Read Pgs. 131-136
Kilocalorie
for tomorrow!
Krebs cycle
Mitochondrial matrix
Oxaloacetic acid
Pyruvic acid
Lactic acid fermentation
NAD+---NADH, FAD+---FADH2
Agenda
What energy carrying compound is made inside the mitochondria?
What occurs during glycolysis?
How is lactic acid fermentation different from alcoholic
fermentation?
• Go over Vocabulary Definitions
• Notes: Mitochondrion structure, Glycolysis
& Fermentation
• Complete Role of ATP in Cells PSSA
Worksheet
• Acetyl CoA -two-carbon molecule
• Aerobic respiration - process that produces large amounts of ATP
• Alcoholic fermentation – form of anaerobic respiration which involves
the conversion of pyruvic acid to ethyl alcohol and carbon dioxide
• Anaerobic - does not require oxygen
• Cellular respiration - process in which cells make ATP by breaking
down organic compounds
• Citric acid -six-carbon molecule in the Krebs cycle
• Fermentation - the recycling of NAD+ under anaerobic conditions
• Glycolysis - pathway in which two molecules of pyruvic acid are
produced
• Kilocalorie - unit of energy
• Krebs cycle -pathway that breaks down acetyl CoA producing carbon
dioxide, hydrogen atoms, and ATP
• Mitochondrial matrix -the space inside the inner membrane of a
mitochondria
• Oxaloacetic acid -four-carbon molecule that combines with Acetyl CoA
• Pyruvic acid - three-carbon product of glycolysis
• Lactic acid fermentation –form of anaerobic respiration which involves
the conversion of pyruvic acid to lactic acid
Vocabulary Quiz is scheduled for Wednesday, April 15th!
Enzymes
36 ADP + 36 P
36 ATP
All living organisms need Energy!
• Photoautotrophs get energy from
sunlight
• Heterotrophs get energy from organic
compounds
• Chemoautotrophs get energy from
inorganic compounds
The ULTIMATE source of energy
for plants and animals is the Sun!
ATP
Regenerated through process of Chemiosmosis
The Organelle of Cellular
Respiration
• Cellular respiration takes place in both
plant and animal cells.
• The organelle in which it takes place is
the mitochondrion. – This is also
known as the ‘power-house’ of the cell.
Stages of Cellular Respiration
• Glycolysis
• If oxygen present: Aerobic Respiration
• If oxygen not present: Fermentation
C6H12O6 + 6O2 --- 6CO2+ 6H2O + energy
Step #1: Glycolysis
• Biochemical pathway
• Glucose is oxidized into two molecules of
pyruvic acid
• Take place in the cytosol ( cytoplasm) of
the cell
• Glucose is
oxidized
(looses electrons)
into two
molecules of
pyruvic
acid(pyruvate).
• Net gain of 2
ATP, 2 NADH
• Glycolysis is inefficient in energyutilization.
– Aerobes organisms performing respiration in
the presence of oxygen
• must go through Kreb’s Cycle and Electron
Transport Chain in order to produce more energy
after glycolysis
– Anaerobes organisms respiring in the
absence of oxygen
• can survive and make use of the energy released
from glycolysis itself
• Two forms of anaerobes are:
– Facultative anaerobes – these can survive in aerobic
and anaerobic conditions.
– Obligate anaerobes – Survive only as anaerobes.
http://www.science.smith.edu/departments/Biology/Bio231/glycolysis.html
Anaerobic Respiration
• Two forms of anaerobic respiration are:
– Alcoholic fermentation
– Lactic Acid Fermentation
Alcoholic Fermentation
• Yeasts, anaerobic bacteria, etc… undergo
alcoholic fermentation.
• In this process, the pyruvic acid from Glycolysis is
converted to Ethanol and Carbon dioxide.
• Commercially, this is used for making wine, bread,
beer
Lactic Acid Fermentation
• This also occurs in human muscle cells during
stress / when oxygen is scarce.
• In this process, the pyruvic acid from Glycolysis
is converted to Lactic acid. No Carbon dioxide
is produced.
• Lactic acid produced can be changed back to
pyruvic acid when oxygen levels return to
normal
Review
• What energy carrying compound is made
inside the mitochondria?
• What occurs during glycolysis?
• How is lactic acid fermentation different
from alcoholic fermentation?
Read Pgs. 137-144 in book &
complete Role or ATP PSSA
Worksheet.
Agenda
How is aerobic respiration different for prokaryotes and
eukaryotes?
What is the main purpose of the Kreb’s Cycle?
How does the efficiency of aerobic respiration with anaerobic
respiration compare?
• Review Vocabulary
• Notes: Aerobic Respiration
• Complete Measuring Respiration PSSA
worksheet
Aerobic Respiration
• Oxygen must be present
• Carried out in:
– Cytosol(cytoplasm) in prokaryotes
– Mitochondrial matrix in eukaryotes
• Stages
– Krebs cycle
– Electron transport chain
Prior to the Krebs Cycle
• The 3-C containing pyruvic acid produced at
the end of Glycolysis is too bulky to enter the
mitochondria from the cytoplasm.
• Hence, it is ‘groomed’ (broken down further) with
the help of Coenzyme A to form Acetyl Co A
• This Acetyl CoA can easily pass into the
mitochondrial matrix, where it undergoes Kreb’s
Cycle.
Krebs Cycle
• Biochemical pathway that takes
place in the mitochondrial matrix
• Breaks down acetyl Co A into citric
acid
• Produces carbon dioxide, hydrogen
atoms, and ATP
• Main purpose is to capture H+
•NAD and FAD pick up
Hydrogen atoms and
take them to the
Electron Transport
Chain
http://www.science.s
mith.edu/department
s/Biology/Bio231/kre
bs.html
Electron Transport Chain
• Redox reactions release energy when electrons pass
through a cascade of electron carrier molecules.
• NADH and FADH release protons to make ATP through
chemosmosis
• Final electron acceptor is oxygen
– Allows e- to keep moving down transport chain, therefore ATP
can be produced.
– Bonds with H+ and released as water .
Review of Stages for Aerobic Respiration
http://www.studystack.com/wordscramble-93931
Net Energetics of Cellular
Respiration Per Molecule of Glucose
Stages of
Net ATP NADH
Cellular
produced produced
Respiration
Glycolysis
2
2
Grooming
of Pyruvic
acid
Kreb’s
Cycle
E.T.C.
Net # of
molecules
FADH2
produced
CO2
produced
0
0
0
2
0
2
2
6
2
4
34
38
0
10
0
2
0
6
Remember Anaerobic Respiration produces only 2 ATP!
Review
• How is aerobic respiration different for
prokaryotes and eukaryotes?
• What is the main purpose of the Kreb’s
Cycle?
• How does the efficiency of aerobic
respiration with anaerobic respiration
compare?
Complete Measuring Respiration PSSA
worksheet
Agenda
• Vocabulary Quiz
• Pea Respiration Lab
• Complete Chapter Review Pg. 146-147
and hand in on Thursday, April 16th
– Understanding Key Concepts #5-11, 13,14
– Critical Thinking #17-20
– Standardized Test Preparation #1-8, Short
Response, Extended Response A & B
Agenda
• Vocabulary Quiz
• Pea Respiration Lab