Transcript Respiration

Cellular
Respiration
Cellular respiration is the process
by which cells make energy.
They use glucose and oxygen to
produce carbon dioxide, water
and ATP (usable energy)
A common misconception
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Many people think “respiration” refers
specifically to “breathing”
Actually respiration refers to the processes of
getting energy from food.
All large animals (including humans) need to
use oxygen to fully release the energy from
food. That’s why the word respiration has
also come to refer to breathing.
The Summary Formula:
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C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy
Glucose + oxygen  carbon dioxide + water
Enough energy is released during cellular
respiration to produce up to 38 molecules of
ATP
38 ADP + 38 PO4  38 ATP
Energy
Energy
(ATP)
Glucose
Water
mitochondrion
Oxygen
cell
Carbon dioxide
Where it all happens: Mitochondiron
Stages of Respiration:
Stage 1. Glycolysis
(The splitting of sugars)
Pyruvic Acid
(CH3COCOOH)
No oxygen available
Lots of oxygen available
Stage 2. Anaerobic
Stage 2a. Aerobic
(The fermentation of Pyruvic Acid)
(the Krebs Cycle)
Stage 2b. Aerobic
A little energy
(2 ATP / glucose molecule)
(Electron Transport)
A lot of energy (38 ATP / glucose)
Glycolysis: Splitting the sugar
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Glucose is split into two 3-carbon molecules
called pyruvic acid
The Steps in Glycolysis are:
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Phosphate from ATP is joined to glucose, making
a 6-carbon phosphate
The 6-C phosphate breaks into 2 PGAL
Hydrogen is removed and phosphate added to
make two 3-carbon phosphates
The two 3-C phosphates are converted to pyruvic
acid, giving off enough energy for 4 ATP
Glycolysis Diagram
Glucose C6H12O6
CCCCCC
2 ATP
6 carbon-phosphate
2 PGAL
3 carbon-phosphate
2 ADP+P Energy “used”
P-CCCCCC-P
2 NAD and 2P
P-CCC P-CCC
P-CCC-P P-CCC-P
2 NADH + H
4 ADP+P
2 Pyruvic Acid (pyruvate)
CH3COCOOH
4 ATP
CCC
CCC
Energy “gained”
Uses of Pyruvic Acid
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The Pyruvic acid can be used for one of
several different pathways, depending on the
organism and the circumstances:
1. For alcoholic fermentation (in yeasts)
2. For lactic acid fermentation (in milk bacteria, and
emergency systems in animals)
3. For aerobic respiration (the Krebs’ cycle) in most
eukaryotes (plants and animals)
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In most animals, the pyruvic acid is first changed to Acetyl
Co-A before being used in Krebs’ cycle
Uses of Pyruvic Acid
Glycolysis
Pyruvic Acid
Co enzyme A
Alcoholic
Fermentation
Lactic Acid
Fermentation
Enzyme
Reaction
NAD
NADH+H
Acetyl Co-A
CO2
Ethyl
Alcohol
CO2
Lactic Acid
Anaerobic Respiration
Krebs Cycle
2 CO2
Electron
Transport
6 H2O
Aerobic Respiration
Lactic Acid Fermentation in Humans
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Humans normally undergo aerobic
respiration (we use oxygen)
Runners sometimes can’t
fast enough to
Under extreme exertion (or when breath
supply their bodies with
suffocating) we don’t get enough oxygen
oxygen.
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Then we use lactic acid fermentation
to produce some energy without
oxygen.
Build-up of lactic acid in muscles can
cause pain and cramps.
Lactic acid build-up
causes pain, fatigue, and
cramps
Steps in aerobic respiration
1.
2.
3.
4.
5.
6.
Pyruvic acid is converted to acetyl Co-A
2 carbons from Acetyl Co-A join onto a 4C
compound (oxaloacetic acid) to make citric acid, a
6C compound (citric acid)
Citric acid gives off one carbon dioxide to make a
5C compound (α-ketoglutaric acid)
This gives off another carbon dioxide to make a 4C
compound (succinic acid)
The 4C compound rearranged (back into
oxaloacetic acid), through two intermediate steps
(fumaric acid and malic acid).
Krebs cycle
Captured hydrogen used to make energy
The Enzyme Reaction
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Pyruvic acid + Co-enzyme A
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CO2 + Acetyl Co-A
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Acetyl Co-A carries two
carbon atoms to the Krebs
cycle, before being turned
back into co-enzyme A
Simplified Krebs Cycle Diagram
C2
Acetyl Co-A
Citric Acid C6
CO2
NADH+H
Oxaloacetic Acid C44
NAD
5-carbon compound C5
(α-ketoglutaric acid)
H2O
H2O
4 Carbon compounds
FAD
NADH+H
4 Carbon compound C4
(fumaric acid & malic acid)
(Succinic acid)
FADH2
CO2
Advanced Krebs cycle
(Optional Enrichment)
CO2
Given off
C
o
2
Hydrogen Stored
(NADH, FADH2)
The Electron Transport Chain
AKA: cytochrome system
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During the reactions of aerobic respiration,
lots of Hydrogen has been captured in
hydrogen storing compounds, including:
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2 NADH from Glycolysis
2 NADH from conversion of Pyruvic Acid
6 NADH from the Krebs cycle
2 FADH2 from the Krebs cycle
Many of the hydrogens have lost electrons
Now the energy of those electrons &
hydrogen ions are used to make ATP
The Electron Transport Chain
The Electron Transport Chain
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Along the inner membrane of the mitochondrion,
electrons are passed from molecule to molecule
The energy from these electrons is used to “pump”
hydrogen ions (H+) into the space between the
membranes
The hydrogen ions diffuse back in, producing ATP
by chemiosmosis (similar to photosynthesis)
The hydrogen ions and electrons are combined with
oxygen to form water.
The Electron Transport Chain
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The simplified outcome of electron transport:
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The hydrogen atoms join with oxygen to make
water.
ADP
Lots of ATP is produced
+P
4 H+ + O2 +4e-  H2O +ENERGY
Energy
ATP
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Remember, up to 38 ATP molecules can be
produced from the complete respiration of a
single glucose molecule.
Other organic molecules, such as starches
and lipids, can produce even more ATP if
they undergo complete respiration.
ATP is the energy exchange medium of the
cell. It provides the energy for most cellular
activity.
Cellular Respiration Videos
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Cellular Respiration (Overview Lecture)
Sugar Goes to ATP (Hey There Delilah)
Cellular Respiration Song ( I Gotta Feeling)
Cellular Respiration (Californication: too long for class)
Student Made Respiration video (not too bad)
Student-made Respiration song (dreadful and full of
spelling mistakes, but mercifully short)
Assignments on Respiration.
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Read Chapter 7, pp. 127 to 138.
Read carefully the chapter summary on page
139.
Do exercises on page 140 # 1 to 20
Draw a diagram to represent the Krebs’ cycle