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CELLULAR RESPIRATION
Chapter 7
7.1 GLYCOLYSIS AND FERMENTATION
If I have a $10.00 bill and a $10.00 check, which is better?
ATP is like cash in the cell
Glucose, NADH, FADH2 are like checks in a cell. They have to be converted
in order to use for energy.
What happens when you breathe on a window? What two things are
released? Water and Carbon Dioxide
These are byproducts of Cellular Respiration
Write down the equation for photosynthesis and cellular respiration. Compare
6CO2 + 6H20 +energy--- C6H1206 +6O2
C6H1206 +6O2 - 6CO2 + 6H20 + ATP
CELLULAR RESPIRATION
Cellular Respiration and Photosynthesis are not the reverse
of each other. The products of photosynthesis are the
starting point of cellular respiration.
1st Law of Thermodynamics: energy is neither created nor
destroyed
Photosynthesis= 686 Kcal of energy in one mole of glucose
Cell. Respiration releases 686 Kcal from one mole of glucose
Cellular Respiration is the process by which cells make ATP
by breaking down organic compounds
There are TWO stages:
Glycolysis and Aerobic Respiration
Stop, Day 1
GLYCOLYSIS
1 molecule of glucose is converted into 2- 3carbon molecules of Pyruvic Acid
and a small amount of ATP and NADH
If Oxygen is present, Pyruvic Acid is broken down and NADH makes a large
amount of ATP. This is Aerobic Respiration.
If no oxygen is present, Pyruvic acid can go through anaerobic pathways called
Fermentation.
FERMENTATION
Many cultures depend on fermentation for their diets.
Examples?
If oxygen is not present, Pyruvic Acid goes along another
pathway. It does not produce ATP, but other organic
molecules that regenerates NAD+ to keep the cycle
going.
In Lactic Acid Fermentation, it converts to lactic acid.
In Alcoholic Fermentation, it converts to ethyl alcohol and
carbon dioxide.
ELECTRON TRANSPORT CHAIN
The electron transport chain allows
the release of the large amount of
chemical energy stored in reduced
NAD+ (NADH) and reduced FAD
(FADH2). The energy released is
captured in the form of ATP (3 ATP
per NADH and 2 ATP per FADH2).
PHOTOSYNTHESIS AND CELLULAR
RESPIRATION
Photosynthesis
Cellular Respiration
Organelle for process
Chloroplast
Mitochondria
Reactants
CO2 and H₂O
Sugars (C₆H₁₂O₆) and
O₂
Electron transport
chain
Proteins with thylakoid
membrane
Proteins with inner
mitochondrial
membrane
Cycle of chemical
reactions
Calvin Cycle in
chloroplasts builds
sugar molecules
Krebs cycle in matrix of
mitochondria breaks
down carbon-based
molecules
Products
Sugars (C₆H₁₂O₆) and
O₂
CO2 and H₂O
CELLULAR RESPIRATION OCCURS IN
1.
2.
3.
4.
Chloroplast
Ribosome
Golgi apparatus
Mitochondria
10
0%
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0%
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0%
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0%
18
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4
FORMS OF ENERGY MUST BE CONVERTED
TO THIS TO BE USED BY THE CELL
1.
2.
3.
4.
NADH
Glucose
ATP
FADH2
10
0%
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4
CELLULAR RESPIRATION


Plants and animals must break down molecules
from food to produce ATP.
They break this down through the process of
Cellular Respiration.
 This is the process that cells make ATP by
breaking down the organic molecules.
 C6H12O6 + 6O2 → 6CO2 + 6H2O
ATP (ADENOSINE TRIPHOSPHATE)


Most of the energy from
cell respiration is
converted into ATP
ATP is a substance that
powers most cell
activities.
CELLULAR RESPIRATION

Mitochondria cannot
make ATP from food.
It must break it down
into smaller molecules
like glucose. Then
glucose is broken
down.
CELLULAR RESPIRATION

Divided into 2 categories:

Glycolysis- this is anaerobic because it
does not require oxygen

Aerobic Respiration- Oxygen is
present in the cells environment
AN ANAEROBIC PROCESS
1.
2.
Requires the
presence of
oxygen
Does NOT require
the presence of
oxygen
10
0%
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GLYCOLYSIS


Splits glucose into
two three-carbon
molecules of pyruvic
acid and makes two
molecules of ATP and
NADH
Pyruvic acid- made
from glucose and
supplies energy to
cells
GLYCOLYSIS
1. Two phosphate groups
are attached to one
molecule of glucose.
2. 6-carbon compound is
split into two threecarbon molecules of G3P
(glyceraldehyde 3phosphate)
3. Two G3P molecules are
oxidized, each receives a
phosphate group.
4. Phosphate groups are
removed and 2 molecules
of pyruvic acid are
produced.

Net yield of 2 ATP
molecules for every
glucose molecule
converted into pyruvic
acid.
WHAT IS NEXT?



If oxygen is present, cellular respiration enters
the pathways or aerobic respiration.
If oxygen is NOT present, anaerobic, some cells
can convert pyruvic acid into other compounds.
Fermentation- combination of glycolysis
and the additional pathways to regenerate
NAD+.
WHAT IS THE NET YIELD OF ATP FROM
GLYCOLYSIS?
1.
2.
3.
4.
4 ATP
2 ATP
6 ATP
8 ATP
10
0%
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2
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8
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0%
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0%
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4
WHAT HAPPENS TO THE PYRUVIC ACID
FERMENTATION



These additional pathways do not produce ATP.
This process recycles NAD+ from NADH. If this
didn’t occur, glycolysis would stop.
The fermentation pathways allow for the
production of ATP to continue.
LACTIC ACID FERMENTATION
Oxygen is absent
 An enzyme converts pyruvic acid (made
from glycolysis) into lactic acid.
 NADH is oxidized to NAD+
 This NAD+ is regenerated used in
glycolysis.

LACTIC ACID FERMENTATION




Occurs in muscles during strenuous
exercise
Muscle cells use oxygen faster than the
receive oxygen
Oxygen becomes depleted, muscle cells
switch to lactic acid fermentation.
Lactic acid builds up, leading to cramps.
WHICH OF THE FOLLOWING OCCURS IN
LACTIC ACID FERMENTATION?
1
Oxygen is consumed
Lactic acid is
converted into
pyruvic acid.
NAD+ is
regenerated for use
in glycolysis
Electrons pass
through the electron
transport
chain
2
3
4
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6
7
8
9
10
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22
1.
2.
3.
4.
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0%
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0%
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0%
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0%
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4
ALCOHOLIC FERMENTATION

Plants and unicellular organisms, like yeast use this

Process of converting pyruvic acid into ethyl alcohol
Co2 makes the
bread rise
ALCOHOLIC FERMENTATION

After glycolysis, requires 2 steps:
CO2 is removed from pyruvic, leaving a 2-carbon
compound
 2 hydrogen are added to the 2-carbon to form ethyl
alcohol
 Regenerates NAD+ for
glycolysis.

EFFICIENCY OF GLYCOLYSIS

Not very efficient on transferring energy from
glucose to ATP

Efficiency is 2%

Ends 7.1 Notes
WHAT HAPPENS TO THE PYRUVIC ACID
CELLULAR RESPIRATION
Aerobic Respiration- Oxygen is present
 2 major stages:
 Krebs Cycle
 Oxidation of glucose, that began in glycolysis
is completed
 Electron Transport Chain
 NADH is used to make ATP

KREBS CYCLE AND ELECTRON TRANSPORT
CHAIN



In prokaryotes, take place
in the cytosol of the cell.
In eukaryotes, take place
in the mitochondria.
Pyruvic acid from
glycolysis diffuses into the
mitochondrial matrix.
KREBS CYCLE
Occurs in the mitochondrion matrix.
 Pyruvic acid enters the matrix, it reacts with
coenzyme A, loses CO2 to form acetyl CoA.
 NAD+ is reduced to NADH.



Glycolysis yields 2 molecules of pyruvic acid and
each react with coenzyme A to form acetyl CoA.
Krebs Cycle- breaks down the acetyl CoA to
produce CO2, hydrogen, and ATP.
KREBS CYCLE

Produces :
 4 CO2
 2 ATP molecules
 Hydrogen molecules that are used to make 6
NADH and 2 FADH2 (electron acceptor)

Glycolysis produces 2 pyruvic acid molecules.
It takes 2 turns of the Krebs cycle to break
down one glucose molecule.
HOW MANY TURNS OF THE KREBS CYCLE DOES
IT TAKE TO BREAK DOWN ONE GLUCOSE
MOLECULE?
1.
2.
3.
4.
1
2
3
4
85%
15%
0%
1
2
3
0%
4
KREB CYCLE PRODUCTION




Glycolysis produces two NADH molecules
The conversion of pyruvic acid to acetyl CoA
produces two more NADH.
Plus the six from Krebs Cycle gives us 10
NADH molecules for every one glucose molecule
oxidized.
The 10 NADH and the 2 FADH2 drive the next
stage.
WHICH OF THE FOLLOWING IS NOT A
PRODUCT OF THE KREBS CYCLE?
1.
2.
3.
4.
CO2
ATP
FADH2
Ethyl alcohol
96%
0%
1
4%
2
0%
3
4
ELECTRON TRANSPORT CHAIN AND
CHEMIOSMOSIS



Electron transport chain- series of molecules
in a membrane that transfer electrons from one
molecule to another
ATP is produced
NADH and FADH2 release hydrogen atoms,
which regenerates NAD+ and FAD.
ELECTRON TRANSPORT




Proteins make up the chain
They use energy from the electrons supplied from
NADH and FADH2 to pump hydrogen ions
against the gradient and across the membrane.
Protons flow back across the membrane later to
produce ATP, through chemiosmosis
Oxygen picks up hydrogen and electrons to form
water.
ATP IS SYNTHESIZED IN CHEMIOSMOSIS WHEN
THIS MOVES ACROSS THE MITOCHONDRIAL
MEMBRANE
1.
2.
3.
4.
NADH
Oxygen
Protons
Citric acid
88%
13%
0%
1
2
0%
3
4
ELECTRON TRANSPORT
ATP YIELD


Total
yield of
38 ATP
Varies
from cell
to cell
EFFICIENCY OF CELLULAR RESPIRATION

39%

Almost 20 times more efficient than glycolysis

Provides ATP that cells need to support the
activities of life.