Conversion of glucose to ATP
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1. Overview
2. Purpose: To Get ATP!
3. Electron Carrier Molecules
4. Mitochondria
5. The Basics of Cell Respiration
6. Glycolysis
7.Pyruvate chemical “grooming”
8. Kreb’s Cycle
9. Electron Transport Chain (Oxidative
Phosphorylation)
10. Cell Respiration Summary
11. Fermentation- Anaerobic Respiration
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Who does it?
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All living things: both autotrophs and heterotrophs
What is it?
Carbohydrates and O2 are used to make ATP (energy).
CO2 and H20 are waste products.
 Involves three steps: glycolysis, kreb’s cycle, and
electron transport chain.
 The opposite of photosynthesis.
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Where does it occur?
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The cytoplasm and the mitochondria of the cell
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Cellular respiration releases energy by
breaking down glucose and other food
molecules in the presence of oxygen.
Equation:
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C6H12O6 + 6O2 6CO2 + 6H20 + ATP
Glucose+ oxygen carbon dioxide + water + energy
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ATP: A modified nucleotide molecule that
powers all cellular work directly.
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Phosphorylation
When ATP releases a phosphate + energy it
produces ADP (adenosine diphosphate)
ADP can turn back to ATP by taking in a
phosphate and energy by phosphorylation
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Similar to recharging a battery
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There are two different molecules that are used
to carry electrons and hydrogen ions to the last
step cellular respiration.
NADH- NAD+
 FADH2- FAD
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Cellular respiration takes place in small steps to
minimize the loss of energy in the form of heat or light.
Processes that require oxygen to take place are called
aerobic.
Processes that do not require oxygen to take place are
anaerobic.
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Aerobic Cellular respiration consists of three
major steps (when oxygen is present):
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Glycolysis – occurs in the cytoplasm
The Krebs cycle – occurs in the matrix of
mitochondrion
Electron transport chain – occurs along the
innermembrane in the cristae of mitochondrion
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Means “splitting sugar”
Occurs in the cytoplasm
Is anaerobic (doesn’t require oxygen)
Glucose (6-C) is split to two molecules of
another organic compound, called pyruvate (3C).
Makes 4 ATP, but uses 2 ATP, for a net gain of
2 ATP
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A net gain of 2 NADH molecules
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ATP can be used by cell immediately
NADH must pass down the ETC in mitochondria
Water is released as waste product
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As pyruvate forms at the end of glycolysis, it is
transported from the cytoplasm into the
mitochondria
Pyruvate does not enter the Kreb’s Cycle as
itself.
It undergoes major chemical “grooming”
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A carbon atom is removed from pyruvate (3-C) forming
acetyl coA (2-C)
NADH molecules are made (per pyruvate-3C)
CO2 is released as a waste product (per pyruvate-3C)
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Occurs in the matrix of the mitochondria
Compared with glycolysis, Kreb’s Cycle pays big energy
dividends to the cell
This makes 1 ATP, 3 NADH and 1 FADH2, per acetyl coA
(2-C) (double that for each glucose molecule)
Releases CO2 as waste
is aerobic (requires oxygen)
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Occurs along the inner membrane of the cristae
of the mitochondria
NADH and FADH2 from glycolysis and Kreb’s
Cycle give up their H+ and electrons to make
ATP
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3 ATP for each NADH and 2 ATP for each FADH2
O2 is the final electron acceptor and becomes
water which is a waste product
Is aerobic and makes most of the energy in cell
respiration.
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TOTAL= 38 ATP (theoretical)
Glycolysis
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Kreb’s Cycle (including pyruvate grooming)
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Occurs in cytoplasm
2 ATP
2 NADH
2 H20 get released
2 pyruvate
2 ATP
8 NADH
2 FADH2
6 CO2 get released
Electron Transport Chain
H20 gets released
 10 NADH get converted to 3ATP= 30 ATP
 2 FADH2 get converted to 2 ATP= 4 ATP
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Glycolysis is the metabolic pathway that
generates ATP during fermentation.
No O2 is required; it generates a net gain of 2
ATP and 2 NADH
Significantly less ATP is generated, but it is
enough to keep your muscles contracting for a
short while when the need for ATP outpaces the
delivery of O2 via the blood stream
Many microorganisms supply all their energy
needs with the 2 ATP yield of glycolysis.
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Fermentation provides an anaerobic step that
recycles NADH back to NAD+; essential to
harvest food energy by glycolysis.
Two types of fermentation:
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Lactic acid
Alcohol
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Lactic acid fermentation
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1. Glycolysis occurs
2. NADH is recycled to NAD+ as pyruvate becomes
to lactic acid.
Lactate builds up in muscle cells during strenuous
exercise is carried in the blood to the liver, where it is
converted back to pyruvate
Dairy industry use this to with bacteria to make
cheese and yogurt
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Alcohol fermentation
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1. Glycolysis occurs
2. NADH is recycled to NAD+ while pyruvate (3-C)
releases a CO2 and becomes ethanol (2-C) (ethyl
alcohol).
Used by yeasts and bacteria
 Used in brewing, winemaking, and baking
 CO2 provides bubbles in beer and champagne, and
bread dough to rise
 Ethanol is toxic to organisms that produce it; must
release it to their surroundings
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