Download Cellular Respiration: Harvesting Chemical Energy

Cellular Respiration:
Harvesting Chemical Energy
Cellular Respiration
All living things need
energy
Energy in the form
of…
Food=chemical
energy
Living things get most of the energy they
need from glucose.
– Autotrophs make glucose using photosynthesis
– Heterotrophs get glucose from food they eat
Cellular Respiration is the process of
extracting stored energy from glucose and
storing it in the high energy bonds of ATP.
What Is ATP?
Energy used by all Cells
Adenosine Triphosphate
Organic molecule containing highenergy Phosphate bonds
Chemical Structure of ATP
What Does ATP Do for
You?
It supplies YOU with
ENERGY!
Why ATP? An analogy to money…
Glucose in our food is a great source of energy!
($100 bill)
However, individual cell processes may only
require a small amount of energy ($1 bill)
Analogy: most vending machines do not accept
$100 bills! We need a smaller form of “currency”
for these processes.
ATP is this important cellular
“currency” for life.
ATP releases more appropriate
amounts of energy for the
individual cellular processes than
does glucose
How Do We Get Energy From
ATP?
By breaking
the highenergy
bonds
between
the last
two
phosphates
in ATP
Results in ADP -Adenosine Diphosphate
(only 2 phosphates)
How efficient is cell respiration?
Energy released
from glucose
(as heat and light)
100%
Burning glucose
in an experiment
Energy released
from glucose
banked in ATP
About
40%
“Burning” glucose
in cellular respiration
Gasoline energy
converted to
movement
25%
Burning gasoline
in an auto engine
ATP is broken down into ADP + P and then remade
again with the help of enzymes in the ATP/ADP
cycle
Respiration
• There are two types of Respiration:
Anaerobic Respiration and Aerobic
Respiration
• Anaerobic Respiration – without oxygen
(referred to as Fermentation)
• Aerobic Respiration – with oxygen
(referred to as Cellular Respiration)
The First Stage for both
types of respiration,
is called Glycolysis
Glycolysis
• glyco means
“glucose/sugar”, and
• lysis means “to split”.
Therefore,
• glycolysis means “to
split glucose”
C-C-C-C-C-C
C-C-C C-C-C
Glycolysis
 Occurs in the cytoplasm
just outside of
mitochondria.
 Needs no oxygen and
makes 2 ATP
 Process in which 1
glucose in broken in half,
producing 2 molecules of
pyruvic acid
C-C-C-C-C-C
C-C-C C-C-C
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Anaerobic
Respiration/Fermentation
(Fermentation does NOT use oxygen)
After Glycolysis, the respiration process
stops with 2 ATP made.
The pyruvate is then changed into one of
several types of molecules, depending on
the type of organism doing the
fermentation
Anaerobic Respiration
The 2 most common forms of
Anaerobic Respiration are:
1. Alcoholic Fermentation,
and
2. Lactic Acid Fermentation
Alcoholic Fermentation
is carried out by yeast,
a kind of fungus.
Alcoholic Fermentation
• Uses only Glycolysis.
• Produces ATP when O2 is not
available.
Alcoholic Fermentation
C6H12O6
(Ethyl Alcohol
or Ethanol)
2 C2H5OH + 2 CO2
As a result of Alcoholic Fermentation,
Glucose is converted into 2 molecules
of Ethyl Alcohol and 2 Molecules of
Carbon Dioxide.
Wine making
Grapes are crushed and the sugar they contain is fermented
by yeasts to produce alcohol and carbon dioxide.
The carbon dioxide usually escapes but if the wine is
bottled before fermentation is complete, the carbon dioxide
dissolves and escapes as bubble when the bottle is opened
This is the case with ‘sparkling’ wines such as Champagne
Brewing
In brewing beer, a sugary product (malt) is dissolved
out of germinating barley
Yeast is added to this solution and fermentation begins,
producing alcohol and carbon dioxide
Some of the carbon dioxide escapes but the rest
dissolves in the beer when it is bottled or put into casks
When the bottles or casks are opened, the dissolved
CO2 escapes as bubbles
Baking
In baking, yeast is added to a mixture of flour and water,
made into the form of a dough
The yeast first changes the flour starch into sugar and then
ferments the sugar into alcohol and CO2
The CO2 forms bubbles in the dough which cause it to
expand (‘rise’)
When the dough is baked, the heat evaporates the
alcohol but makes the trapped bubbles expand giving the
bread a ‘light’ texture
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Dough rising
The yeast is mixed
with the dough
After 1 hour in a
warm place the dough
has risen as a result
of the carbon dioxide
produced by the yeast
37
The ‘holes’ in the
bread are made by
the carbon dioxide
bubbles.
This gives the
bread a ‘light’
texture
Lactic Acid Fermentation
• Uses only Glycolysis.
• Does NOT use O2
• Produces ATP when O2 is
not available.
Lactic Acid Fermentation
• Performed by bacteria
• Results in yogurt, pickles, sauerkraut
and kimchi
Lactic Acid Fermentation
• Carried out by human muscle
cells under oxygen debt.
• Lactic Acid is a toxin and
causes fatigue, soreness and
stiffness in muscles.
Fermentation - Summary
• Releases 2 ATP from the
breakdown of a glucose
molecule
• Provides ATP to a cell even
when O2 is absent.
Aerobic Respiration
Aerobic Respiration
requires oxygen!
There are three phases to Aerobic
Respiration ... they are:
1. Glycolysis (same as the glycolysis of
anaerobic respiration)
2. Krebs cycle (AKA - Citric Acid cycle)
3. Oxidative Phosphorylation and The
Electron Transport Chain
Aerobic Respiration takes place in
both the cytoplasm (Glycolysis) and
in the mitochondria of a cell
Comparing Aerobic
and
Anaerobic Respiration
• Aerobic Respiration–requires a mitochondrion and oxygen
–is a three phase process
• Anaerobic –
–does not require oxygen
–consists of one phase only-Glycolysis
Mitochondria
 Organelle where cellular respiration takes
place.
Cellular Respiration
 An exergonic, oxygen (O2) requiring process that uses
energy extracted from organic molecules (glucose) to
produce energy (ATP) and water (H2O).
C6H12O6 + 6O2  6CO2 + 6H2O + 36 ATP
Glucose
oxygen
Carbon
dioxide
water
ENERGY
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Breakdown of Cellular Respiration
Three main parts (stages).
1. Glycolysis (splitting of sugar)
2. Krebs Cycle (Citric Acid Cycle)
3. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
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1. Glycolysis
 Occurs in the cytoplasm
just outside of
mitochondria.
C-C-C-C-C-C
 Needs no oxygen and
makes 2 ATP
 Process in which 1
glucose in broken in half,
producing 2 molecules of
pyruvic acid
C-C-C C-C-C
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2. Krebs Cycle (Citric Acid Cycle)
Occurs in the mitochondria
Makes 2 ATP
Pyruvic acid is broken down into CO2 in a
series of energy-extracting reactions
Citric Acid is created in this cycle thus
giving it the nickname Citric Acid Cycle.
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3. Electron Transport Chain (ETC)
Location: mitochondria
Makes 32 ATP
Uses high-energy e- from Krebs
Cycle to make ATP
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TOTAL ATP YIELD
The ETC makes the most ATP
In total cellular respiration makes
36 ATP
ATP
49
Krebs Cycle and
ETC require oxygen
to work!
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Cellular Respiration Flowchart
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
One example of respiration in ourselves
2. The lungs absorb oxygen
from the air
2.The stomach and
intestine digest food.
One of the products
is glucose
4 RESPIRATION
Glucose and
oxygen react to
produce energy
for muscle
contraction
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1. Air taken in
1.Food taken in
3.The blood stream
carries glucose and
oxygen to the
muscles
5 Carbon dioxide
is carried to the lungs
by the blood
Respiration - Summary
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
Lactic Acid