Download Cellular Respiration

Cellular Respiration
Chapter 6
Energy Flow and Chemical Cycling
in the Biosphere
 Fuel molecules in food


represent solar energy
traced back to the sun
 Animals depend on plants:


to convert solar energy to
chemical energy
In form of sugars and other
organic molecules
Producers and Consumers
 Autotrophs



Producers
Make own organic matter from inorganic nutrients
Photosynthesis
 Heterotrophs



Consumers
Cannot make organic molecules from inorganic ones
Cellular respiration
Chemical Cycling between
Photosynthesis and Cellular Respiration
 The ingredients for
photosynthesis:


CO2 obtained from the air
H2O obtained from the damp soil
 Chloroplasts rearrange the
atoms of these ingredients


produce sugars (glucose) and
other organic molecules
Oxygen gas a by-product of
photosynthesis
Cellular Respiration
 Release of energy from molecules
accompanied by the use of this energy to
synthesize ATP molecules
 Metabolic pathway
 Main method that chemical energy is
harvested from food and converted to ATP
 Aerobic

Requires oxygen and gives off carbon
dioxide
 Oxidation – reduction reaction


Glucose oxidized
Oxygen reduced
Redox Reaction (O-R)
 Chemical reaction
that transfers
electrons from one
substance to another
 Oxidation

Oxidation
Loss of electrons
 Reduction

Acceptance of
electrons
Reduction
ATP
 Adenosine triphosphate (ATP)



Nucleotide with the base
adenine and the sugar ribose
Main energy carrier in cells
Formed during reactions that
breakdown organic
compounds to CO2 and water



Requires ample oxygen
Occurs within the
mitochondrion
Hydrolyzes phosphates to
release energy

form adenosine
diphosphate (ADP)
Cellular respiration
 Cellular respiration and
breathing are closely related


Cellular respiration requires a cell
to exchange gases with its
surroundings
Breathing exchanges these
gases between blood and
outside air
Where Is the Energy in Food?
 The process of aerobic respiration requires
oxygen and carbohydrates
C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy
 The products are carbon dioxide, water, and
energy (heat or ATP)
The Players….
 Glucose
 NAD
 FAD
Where Is the Energy in Food?

Cellular respiration takes place in three stages:
1.
2.
3.
Glycolysis
Citric Acid Cycle
Electron transport
1. Glycolysis
 Occurs in the
cytoplasm
 Glucose split into 2
molecules

Pyruvate
 Does not require
oxygen to generate
ATP
 Then, enters aerobic
or anaerobic
reactions
2. Citric Acid Cycle
 “Krebs Cycle”
 occurs within the
mitochondrion
 Converts pyruvic
acid – acetic acid –
Acetyl CoA
 electrons passed to
an electron transport
chain in order to
power the production
of ATP
3. Electron transport chain
 Uses electrons to make ATP
 NAD & FAD

Carry electrons from the
cytoplasm or the mitochondrial
matrix and carry them to the
mitochondria

NADH and FADH2 transfer their
electrons to a series of
membrane-associated molecules
Fermentation
 Occurs when O2 is
not available
 Animal cells convert
pyruvate to lactate
 Other organisms
convert pyruvate to
alcohol and CO2