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Converting Energy
Chapter 5
Part 1:
Cellular Respiration
Prior Knowledge
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Metabolism (p.7)
Glucose (p.34)
Energy and Chemical Reactions (p.38)
Enzymes (p. 40 & 41)
Mitochondria (p.65)
Chloroplast (p.66)
Energy flow in Ecosystems (p.345-347)
Water and Carbon Cycles (p.351-352)
Autotroph & Heterotrophs
Energy and Living Things
• Energy is the ability to move or change matter
(light, heat, chemical, electrical, etc.)
• Energy can be stored or released by chemical reactions.
• Energy from the sunlight flows through living systems,
from autotrophs to heterotrophs.
• Cellular respiration and photosynthesis form a cycle
because one process uses the products of the other.
• ATP supplies cells with energy needed for metabolism.
ATP
(adenosine triphosphate)
• Cells need a steady supply of ATP to
function
• ATP is produced through the process of
cellular respiration
• produced in the mitochondria
ATP
• It is a nucleotide (nitrogen containing base:
adenine, a 5 carbon sugar:ribose, phosphate
group) with two extra energy-storing
phosphate groups
ATP
• The phosphate groups store energy like a compressed
spring does. This energy is released when the bonds
that hold the phosphate groups together are broken.
• The removal of a phosphate group from ATP produces
adenosine diphosphate, or ADP. This reaction releases
energy in a way that enables the cell to use energy.
• Cells use the energy released by this reaction to power
metabolism.
Tour de France:
How do they do it?
5,900 - 9,000 :
Calories consumed by a rider
per day
2,241 miles:
the total distance
42,000:
water bottles used by teams in
race
3: number of weeks the tour
lasts
http://www.tourdefrancenews.com/tourdefrance/daily
Major Parts of the Machine
food, water intake
oxygen intake
Digestive System
Absorption
nutrients,
water,
salts
Respiratory System
oxygen
carbon
dioxide
Circulatory System
elimination
of food
residues
rapid transport
to and from all
living cells
Based on: Starr, C. Biology:
Concepts and Applications,
Brooks/Cole
elimination
of carbon
dioxide
Systems involved:
Digestive system – nutrient absorption from food
Circulatory system – gas exchange
Respiratory system – gas exchange
Cellular Respiration :
*Process by which cells produce energy (ATP) from
breaking down glucose
*Reactants: oxygen & glucose
*Products: carbon dioxide, water, ATP
Enzymes are specialized proteins that catalyse,
affect the rate, of metabolic processes
Cellular Respiration Equation:
enzymes
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
glucose + oxygen
 carbon dioxide + water + ATP (energy)
Stage 1: Glycolysis
- Can take place with or without oxygen
- Converts glucose to 2 molecules of pyruvic acid
- Uses 2 ATP molecules but produces 4 ATP
molecules = net gain of 2ATP molecules
- Occurs in cytoplasm of cell on mitochondrial
outer membrane
Cellular Respiration
Stage 1:Gycolysis
glucose
2 ATP
2 pyruvic acid
Oxygen Independent
(can take place with without O2)
Stage 2: Oxygen Required
Production of ATP
Kreb’s Cycle
- Aerobic reaction
oxygen must be present
to start cycle
- 2 pyruvic acids enter
mitochondria
- Pyruvic acid binds with
acetyl-CoA
- Produces CO2 as a waste
product
Stage 2: Production of ATP
Oxygen required
The Electron Transport Chain
- Aerobic
- Inner membrane of the mitochondria
Cellular Respiration
Stage 2: With Oxygen
pyruvic acid
+O2
Krebs cycle,
CO2
H2O
electron transport chain
(in mitochondria)
36 ATP (energy)
molecules formed
Result of Aerobic Respiration
Process
Net ATP
Glycolysis
2
Kreb’s Cycle
Electron Transport
Chain
Total ATP production
from one molecule
of glucose
36
38
Fermentation:
Respiration in the absence of Oxygen
- Breakdown of carbohydrates in the
absence of oxygen
- When there is no O2 available for Kreb’s
cycle, cells undergo fermentation
- Anaerobic process (no oxygen used)
- ATP is still produced until oxygen returns
to cells
Cellular respiration
Stage 2: No oxygen present
pyruvic acid
CO2
alcohol (in yeasts or some bacteria)
or lactic acid
Types of Fermentation:
- Lactic acid
fermentation –
produces lactic
acid as byproduct
- Alcoholic
fermentation –
produces ethanol
- Carbon dioxide
- Lactic acid
released by yeast
fermentation by
causes the rising of
some prokaryotes
bread dough and
and fungi is used in
the carbonation of
the production of
some alcoholic
foods – cheese and beverages.
yogurt
More on lactic acid
Some cells such as muscle cells revert to
fermentation when oxygen is in short supply
(exercise). Blood cannot supply O2 fast enough,
therefore, they produce ATP without using O2. The
product is lactic acid. In high concentrations, lactic
acid causes fatigue & muscle failure (sore
muscles). Muscle cells will return to normal when
O2 is supplied to chemically change lactic acid.
There is current research that says that muscle
soreness could be more related to actually tears in
the muscle tissues and that lactic acid quickly leaves
the muscles.
Comparing Anaerobic vs. Aerobic
Lactic Acid
Fermentation
Glucose
Alcoholic
Fermentation
Glucose
Aerobic
Respiration
Glucose
Glycolysis
Glycolysis
Glycolysis
Lactic acid
and 2 ATP
Carbon
Carbon
dioxide,
dioxide, water,
ethanol, 2 ATP
and 38 ATP
Production of ATP is more efficient in
the presence of oxygen!
Glucose making 2 molecules of
pyruvic acid in an anaerobic
environment
Stage 1
Pyruvic acid is converted to
carbon dioxide and
water and 36 molecules
of ATP are produced
Stage 2: O2 present
Pyruvic acid is converted to
carbon dioxide and either
alcohol or lactic acid
Stage 2: No O2 present
GLYCOLYSIS
KREB’S CYCLE
(CITRIC ACID CYCLE)
Electron Transport
Chain
Fermentation
What happens to the excess
CO2 produced in the cell as
a waste product of
respiration?
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
It is taken to the lungs and exhaled
out of the body
What would happen to a
cell if it had no
mitochondria?
It would not be able to produce
energy and would die.