Download 2.8 Respiration

Essential Idea
• Cell respiration supplies energy for the
functions of life.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Understanding
• Cell respiration is the controlled release of
energy from organic compounds to produce
ATP.
• ATP from cell respiration is immediately
available as a source of energy in the cell.
• Anaerobic cell respiration gives a small yield of
ATP from glucose.
• Aerobic cell respiration requires oxygen and
gives a large yield of ATP from glucose.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
IB Assessment Statement
• Define cell respiration.
• http://www.youtube.com/watch?v=00jbG_cf
GuQ
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Define Respiration
• Cell respiration is the controlled release of energy from
organic compounds in cells to form ATP.
• ATP or Adenosine triphosphates is the molecule which
directly fuels the majority of biological reactions.
– Everyday each person will hydrolyse (reduce) 1025 ATP
molecules to ADP.
– The ADP is reduced back to ATP using the free energy
from the oxidation of organic molecules.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
ATP = Life’s energy currency $$$$
• ATP (adenosine triphosphate) is the cell’s
energy shuttle
• ATP provides energy for cellular functions
Chemical Energy and ATP
ATP consists of:
– adenine
– ribose (a 5-carbon sugar)
– 3 phosphate groups
Adenine
Ribose
ATP
Copyright Pearson Prentice Hall
3 Phosphate groups
Chemical Energy and ATP
Storing Energy
ADP has two phosphate groups instead of three.
A cell can store small amounts of energy by adding
a phosphate group to ADP.
ATP
ADP
+
Adenosine Diphosphate
(ADP) + Phosphate
Partially
charged
battery
Energy
Energy
Fully
charged
battery
Copyright Pearson Prentice Hall
Adenosine Triphosphate (ATP)
Chemical Energy and ATP
Releasing Energy
Energy stored in ATP is released by breaking the
chemical bond between the second and third
phosphates.
2 Phosphate groups
P
ADP
Copyright Pearson Prentice Hall
• The bonds between the phosphate groups of
ATP’s tail can be broken by hydrolysis
• Energy is released from ATP when the terminal
phosphate bond is broken
P
P
P
Adenosine triphosphate (ATP)
H2O
Pi
+
Inorganic phosphate
P
P
+
Adenosine diphosphate (ADP)
Energy
The Regeneration of ATP
• ATP is a renewable resource that is regenerated by
addition of a phosphate group to ADP
• The energy to phosphorylate ADP comes from catabolic
reactions in the cell
• The chemical potential energy temporarily stored in ATP
drives most cellular work
ATP
Energy from catabolism
(energonic, energyyielding processes)
ADP +
P
Energy for cellular work
(endergonic, energyconsuming processes)
i
Chemical Energy Transfer Food to ATP
• http://www.biologyinmotion.com/atp/index.html
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Pathways of cellular respiration and
Production of ATP
• There are several steps to the process of cellular
respiration but the overall chemical equation is
below:
• C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (ATP + heat)
• Overall this equation states that glucose reacts with
oxygen to form/ produce carbon dioxide and water
• Note: Cellular respiration releases energy. It is
therefore a exothermic (exergonic) reaction.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
IB Assesment Statement
• State that, in cell respiration, glucose in the
cytoplasm is broken down by glycolysis into
pyruvate, with a small yield of ATP.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Stages of Cellular Respiration: A Preview
•
Cellular respiration has three stages:
1. Glycolysis (breaks down glucose into two
molecules of pyruvate)
2. The citric acid cycle/ Krebs Cycle (completes
the breakdown of glucose)
3. Oxidative phosphorylation (accounts for most of
the ATP synthesis)
•
The latter process generates most of the ATP is
called oxidative phosphorylation because it is
powered by redox reactions
Glycolysis harvests energy by oxidizing glucose to
pyruvate
• Glycolysis (“splitting of sugar”) breaks down
glucose into two molecules of pyruvate
• Glycolysis occurs in the cytoplasm
• Requires NO oxygen and so is considered an
Anaerobic Reaction
• The overall reaction for glycolysis is for every one
molecule of glucose used:
– 2 molecules of Pyruvate are formed
– 2 net molecules of ATP are formed
– 2 molecules of NADH are formed
Glycolysis
• Location: Cytoplasm
• Process: Glycolysis
• Substrate: Glucose
• Products: 2 Pyruvate and a small amount of ATP
• Glycolysis does not use oxygen.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Glycolysis Animation
• Watch Animation for more details:
• http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapt
er25/animation__how_glycolysis_works.html?is
bn=0072507470&firstName=&MI=&lastName=
&myEmail=&myStyle=&profEmail=&profStyle=
&taEmail=&taStyle=&otherEmail=&otherStyle=
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
IB Assessment Statement
• Explain that, during anaerobic cell respiration,
pyruvate can be converted in the cytoplasm into
lactate, or ethanol and carbon dioxide, with no
further yield of ATP.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Fermentation allows glycolysis to continue.
Fermentation allows glycolysis to continue making ATP when
oxygen is unavailable.
• Fermentation is an anaerobic process.
– occurs when oxygen is not available for
cellular respiration
– does not produce ATP
There are two types
of Fermentation/
anaerobic
respiration
1. Lactic Acid
Fermentation
Glucose
CYTOPLASM
Pyruvate
No O2 present
Fermentation
O2 present
Cellular respiration
MITOCHONDRION
2. Alcoholic
Fermentation
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle
Anaerobic Respiration
• Anaerobic respiration is the oxidation of
organic compounds without oxygen.
• It is less efficient than aerobic respiration (with
oxygen).
• There are different types of anaerobic
respiration. Here we will compare anaerobic
respiration in yeast and humans.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Humans anaerobic respiration
• Location: cytoplasm
• Substrate: Glucose
• Product: lactic acid (lactate) + ATP
•
Note: lactic anaerobic respiration supplements aerobic respiration in the
production of ATP. Both aerobic and anaerobic respiration can take place in
the human cell at the same time
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Humans anaerobic respiration
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Exercise and anaerobic respiration :
•
Human lactic anaerobic respiration is a process that supplements
the production of ATP.
•
The lactic pathway is so inefficient that under normal circumstances it
cannot produce enough energy to support human systems.
•
In describing the lactic pathway it is often suggested that sprinters 'do
not breath during the 100m sprint' (they do, just watch any video) and
they only produce ATP for running from the lactic pathway.
•
This is a mis-representation of a complex response to the demand for
ATP. It is far better to consider that anaerobic respiration in humans
supplements (adds to) the aerobic production of ATP.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Yeast anaerobic respiration:
• Location: cytoplasm
• Substrate: Glucose
• Product: Ethanol + carbon dioxide + ATP
•
This is the end point for this fermentation reaction. Ethanol and CO2are both excreted
with no further metabolism of the energy stored in the ethanol (very inefficient)
•
Note: The glucose molecule has been hydrolysed further than in human respiration.
Some organisms are totally anaerobic others can switch between anaerobic and aerobic.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Yeast anaerobic respiration:
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Anaerobic respiration:
• Fermentation respiration in yeast yields two useful
products from a human perspective.
• The carbon dioxide can be used in a variety industrial
processes the best known of which is to raise bread.
•
Many Brewers of alcohol will bottle the CO2 for use in the
'carbonation' of other drink products.
• The alcohol itself is of course the basis of many industries
such as beer brewing.
• In more recent time the use of fermentation products is
being used as an alternative source of fuel such as is the
case in fuel for automobiles.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
IB Assessment Statement
• Explain that, during aerobic cell respiration,
pyruvate can be broken down in the mitochondrion
into carbon dioxide and water with a large yield of
ATP
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Aerobic Respiration
• Location: Mitochondria
• Substrate: Pyruvate
• Products: ATP, Carbon dioxide, water and heat.
•
The production of ATP in the aerobic pathway is much greater than in either
glycolysis or the anaerobic alternatives. The oxygen breathed in during
ventilation is sent form the lung into the blood and then transported to the cell.
The oxygen diffuses into the cell and then into the mitochondria for aerobic
respiration
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Aerobic Respiration
• This diagram is a summary of the complete
aerobic pathway.
• The by-product carbon dioxide is excreted
and of course the heat produced is important
in thermoregulation
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Aerobic Respiration
• (a) Glucose transported to
the cell diffuses into the
cytoplasm. Glucose is the
initial substrate for
respiration.
• (b) Glycolysis in which
glucose with six carbons
is broken down into two
Pyruvate each with 3
carbons. This yields a
small amount of ATP.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Aerobic Respiration
• (c) Anaerobic respiration
in which lactic acid is
produced, oxidation from
glucose yields a small
amount of ATP.
•
Remember that anaerobic respiration will occur at the
same time as aerobic respiration to provided more
energy.
• (d) Aerobic respiration in
which pyruvate is broken
down, oxidised, further in
the mitochondria where a
lot of ATP is produced.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Aerobic Respiration
(e) Oxygen is required for
step (d)to be completed. This
is transported to the cell on
the haemoglobin found
inside red blood cells.
• (f) carbon dioxide is
produced as waste from
aerobic respiration it
diffuses into the blood and
is transported to the lungs
where it is excreted in
exhaled air.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 9-6_1
Glycolysis
Pyruvate
Glucose
Cytosol
Mitochondrion
ATP
Substrate-level
phosphorylation
LE 9-6_2
Glycolysis
Pyruvate
Glucose
Cytoplasm
Krebs
cycle
Mitochondrion
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
LE 9-10
MITOCHONDRION
CYTOPLASM
NAD+
NADH
+ H+
Acetyl Co A
Pyruvate
Transport protein
CO2
Coenzyme A
LE 9-6_3
Electrons carried
via NADH and
FADH2
Electrons
carried
via NADH
Glycolysis
Pyruvate
Glucose
Cytosol
Citric
acid
cycle
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Mitochondrion
ATP
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation
This is all occur in the folds of the inner membrane
of the mitochondria
1
mitochondrion
ATP
matrix (area enclosed
by inner membrane)
and
6CO
2
energy
2
3
energy from
glycolysis
6O
and
2
inner membrane
ATP
and
6H O2
4
LE 9-16
Electron shuttles
span membrane
CYTOSOL
2 NADH
Glycolysis
Glucose
2
Pyruvate
MITOCHONDRION
2 NADH
or
2 FADH2
2 NADH
2
Acetyl
CoA
6 NADH
Citric
acid
cycle
+ 2 ATP
+ 2 ATP
by substrate-level
phosphorylation
by substrate-level
phosphorylation
Maximum per glucose:
About
36 or 38 ATP
2 FADH2
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ about 32 or 34 ATP
by oxidation phosphorylation, depending
on which shuttle transports electrons
form NADH in cytosol
LE 9-18
Glucose
CYTOSOL
Pyruvate
No O2 present
Fermentation
O2 present
Cellular respiration
MITOCHONDRION
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Practice Questions
• Compare anaerobic and aerobic respiration
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Skills and Applications
• Application: Use of anaerobic cell respiration in
yeasts to produce ethanol and carbon dioxide
in baking.
• Application: Lactate production in humans
when anaerobic respiration is used to
maximize the power of muscle contractions.
• Skill: Analysis of results from experiments
involving measurement of respiration rates in
germinating seeds or invertebrates using a
respirometer.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings