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Cell Respiration
Releasing Chemical Energy
Introduction
• All organisms must have energy to
carry out life processes.
• Where does this energy come from?
Autotrophs collect energy
from the sun and store it as
organic compounds.
The Need for Energy
• No Energy
= no work
•Energy = Work
Respiration: An
Overview
•
Metabolism is all of the chemical
reactions in the body.
These reactions are either:
1. Synthesis – combining small molecules to
make complex molecules OR
A + B ---> AB
8 Fe + S8 ---> 8 FeS
2. Decomposition reactions – breaking down
molecules into simpler forms.
AB ---> A + B
2 H2O ---> 2 H2 + O2
Reactions Continued
• Synthesis reactions require energy –
example photosynthesis.
• Decomposition reactions release
energy.
• This energy can be used to make ATP
• ATP is a small, useable packet of
energy.
Cellular Respiration
• Cell Respiration is a decomposition reaction
that provides the energy cells need to
function.
• In this series of reactions, sugars, proteins,
and lipids are broken down (decomposed)
and energy is released.
Types of Cellular
Respiration
•
There are two types of cell respiration
– aerobic and anaerobic.
1. Aerobic respiration occurs in the
presence of oxygen.
2. Anaerobic respiration occurs in the
absence of oxygen.
Raw Materials for Cell
Respiration
• What are the raw
materials for cell
respiration?
Carbohydrates,
proteins, and
lipids
• How does the food
become the raw
materials?
•Food is digested into
carbohydrates, lipids,
and proteins.
Glucose and Glycogen
• Glucose is the form in
which animals
transport
carbohydrates through
the blood stream.
• Glycogen is the form
in which it is stored in
animals.
• Glycogen is stored in
the liver and muscles.
Mitochondria
• Mitochondria
are the energy
factories of
the cells.
Mitochondria
• Cellular Respiration occurs in the mitochondriaan organelle in the cytoplasm of cells.
They have:
• an outer membrane that encloses the entire
structure
• an inner membrane that encloses a fluid-filled
matrix
• between the two is the intermembrane space
• the inner membrane is elaborately folded with
shelf-like cristae projecting into the matrix.
Stages of Cell Respiration
1. Glycolysis
2. Kreb’s Cycle
3. Electron Transport System
Glycolysis
• Glycolysis happens in the cytoplasm.
• Glucose is split into 2 three-carbon
molecules.
• Enzymes partially oxidize glucose and this
partial oxidation releases energy that
forms a small amount of ATP.
• This is an anaerobic process and 2 net ATP
are generated.
• This ATP is used to start the Kreb’s Cycle.
Glycolysis Animations
http://www.copernicusproject.ucr.edu/ssi/HSB
iologyResources.htm
Kreb’s Cycle
• The Kreb’s cycle completes the
decomposition and oxidation of glucose to
carbon dioxide.
• The carbon dioxide is released as a gas.
• The oxidation of one glucose molecule
yields up to 38 ATP molecules under ideal
conditions (this occurs infrequently)
• The reaction of acetyl CoA with
oxaloacetate starts the cycle by producing
citrate (citric acid).
• In each turn of the cycle, two molecules of
CO2 are produced as waste products, plus
three molecules of NADH, one molecule of
GTP, and one molecule of FADH2.
• The number of carbon atoms in each
intermediate is shown in a yellow box. (see
picture next slide)
Krebs Cycle Animations
• http://www.science.smith.edu/departments/
Biology/Bio231/krebs.html
• http://www.wiley.com/legacy/college/boyer/
0470003790/animations/tca/tca.htm
The Electron Transport Chain
• It is composed of the mitochondrial
enzymes that transfer electrons from one
complex to another, eventually resulting in
the formation of ATP.
• In the first part, electrons are transferred
from protein to protein and energy is lost as
free energy along the way.
ATP Synthetase
• This free energy is used to move protons
into the matrix of the mitochondria.
• As they pass through the matrix, they pass
through the ATP –synthetase enzyme.
• This causes a charge differential (gradient)
which drives the forming of ATP from ADP.
Electron Transport
• http://www.wiley.com/legacy/college/boyer/
0470003790/animations/electron_transport/
electron_transport.htm
• http://www.science.smith.edu/departments/
Biology/Bio231/etc.html
• http://www.sp.uconn.edu/~terry/images/ani
m/ETS.html
ATP Synthesis
• http://telstar.ote.cmu.edu/biology/animation/
ATPSynthesis/biochem.html
• http://www.sp.uconn.edu/~terry/images/ani
m/ATPmito.html