Download CELLULAR RESPIRATION - Ms. Tripp

Figure 6.0-1
CELLULAR RESPIRATION:
AEROBIC HARVESTING OF ENERGY
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6.1 Photosynthesis and cellular respiration
provide energy for life
• In cellular respiration,
• With the help of oxygen, sugar (created in
photosynthesis) is broken down to carbon dioxide
and water and
• the cell captures some of the released energy to
make ATP.
• Cellular respiration takes place in the mitochondria
of eukaryotic cells.
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Figure 6.1
Sunlight
energy
ECOSYSTEM
CO2 + H2O
Photosynthesis in
chloroplasts Organic
molecules
Cellular
respiration in
mitochondria
ATP powers most
cellular work
ATP
Heat
energy
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+ O2
6.2 Breathing supplies O2 for use in cellular
respiration and removes CO2
• Respiration, as it
relates to breathing,
and cellular respiration
are not the same.
• Cellular respiration is
the aerobic (oxygenrequiring) harvesting
of energy from food
molecules by cells.
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6.3 Cellular respiration banks energy in ATP
molecules
• Cellular respiration is an exergonic (energyreleasing) process that transfers energy from the
bonds in glucose to form ATP.
• Cellular respiration
• can produce up to 32 ATP molecules for each
glucose molecule
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6.5 Cellular respiration is a redox reaction
• The movement of electrons from one molecule to another is an
oxidation-reduction reaction (redox).
– the loss of electrons from one substance is oxidation
– the addition of electrons to another substance is reduction
• Cellular respiration uses redox reactions to harvest the chemical
energy stored in a glucose molecule.
– In cellular respiration the electron movements are
represented by the movement of hydrogens
– This is accomplished by oxidizing the sugar to CO2 and
reducing O2 to H2O.
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STAGES OF CELLULAR RESPIRATION
6.6 Overview: Cellular respiration occurs in
three main stages
• Cellular respiration consists of a sequence of steps
that can be divided into three stages.
• Stage 1: Glycolysis
• Stage 2: Pyruvate oxidation and the citric acid cycle
• Stage 3: Oxidative phosphorylation
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6.6 Overview: Cellular respiration occurs in
three main stages
• Stage 1: Glycolysis
• occurs in the cytosol,
• begins cellular respiration, and
• breaks down glucose into two
molecules of a three-carbon
compound called pyruvate.
• there is a net gain of 2 ATP
and 2 NADH electron carriers.
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6.7 Glycolysis harvests chemical energy by
oxidizing glucose to pyruvate
• ATP is formed in glycolysis by substrate-level
phosphorylation during which
• an enzyme transfers a phosphate group from a
substrate molecule to ADP and ATP is formed.
• Stage 2: Pyruvate oxidation and the citric acid
cycle, also called the Krebs cycle
•
•
•
•
takes place in mitochondria
turns pyruvate to a two-carbon compound (Acetyl CoA)
Acetyl CoA then enters the Citric Acid Cycle
supplies stage 3 with electrons.
• generates 2 ATP, 6 NADH, and 2 FADH2.
• Both processes release CO2
• Stage 3: Oxidative phosphorylation
• Electrons from NADH and FADH2 are passed down the electron
transport chain to O2, which picks up H+ to form water.
• As the ETC shuttles electrons, it pumps H+ across the
membrane, and produces a concentration gradient of H+ across
the membrane.
• In chemiosmosis, the potential energy of this concentration
gradient is used to make ATP.
• Releases H20
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INTERMEMBRANE SPACE
The movement of H+
ions power a protein
turbine, ATP
synthase, that
converts ADP and a
phosphate group into
about 28 ATP.
H+
Rotor
Internal
rod
Catalytic
knob
ADP
+
P
MITOCHONDRIAL MATRIX
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ATP
Figure 6.12
CYTOSOL
MITOCHONDRION
2 NADH
Glycolysis
2
Pyruvate
Glucose
6 NADH + 2 FADH2
2 NADH
Pyruvate
Oxidation
2 Acetyl
CoA
Oxidative
Phosphorylation
(electron transport
and chemiosmosis)
Citric Acid
Cycle
O2
Maximum
per glucose:
H2O
+2
ATP
by substrate-level
phosphorylation
Video Animation
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CO2
+2
ATP
by substrate-level
phosphorylation
+ about
28 ATP
About
32 ATP
by oxidative
phosphorylation
FERMENTATION: ANAEROBIC
HARVESTING OF ENERGY
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6.13 Fermentation enables cells to produce
ATP without oxygen
• Fermentation is a way of harvesting chemical
energy that does not require oxygen (Anaerobic).
• Fermentation
• takes place in the cytosol,
• uses glycolysis,
• produces two ATP molecules per glucose
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What if oxygen is missing?
O2
• No oxygen available = can’t complete aerobic
respiration
• Anaerobic respiration
• also known as fermentation
• no oxygen or
no mitochondria (bacteria)
• can only make very little ATP
• large animals cannot survive
yeast
bacteria
Anaerobic Respiration
• Two types of fermentation
1. alcohol fermentation
• yeast
• glucose  ATP + CO2+ alcohol
• make beer, wine, bread
2. lactic acid fermentation
• bacteria, animals
• glucose  ATP + lactic acid
• bacteria makes yogurt
• animals feel muscle fatigue
O2
6.13 Fermentation enables cells to produce
ATP without oxygen
• The dairy industry uses lactic acid fermentation by
bacteria to make cheese and yogurt.
• Other types of microbial fermentation turn
soybeans into soy sauce and cabbage into
sauerkraut.
• Cellular Respiration and Fermentation
CrashCourse
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