Transcript Cellular Respiration

Harvesting Chemical Energy
So we see how energy enters food chains (via
autotrophs) we can look at how organisms use
that energy to fuel their bodies.
Plants and animals both use products of
photosynthesis (glucose) for metabolic fuel
Heterotrophs: must take in energy from
outside sources, cannot make their own e.g.
animals
When we take in glucose (or other carbs),
proteins, and fats-these foods don’t come to
us the way our cells can use them
Cellular Respiration
Cellular Respiration is the process
that releases energy by breaking
down food molecules in the presence
of oxygen.
These reactions proceed the same
way in plants and animals.
6O2 + C6H12O6  6CO2 + 6H2O +
Energy
Oxygen + Glucose  Carbon Dioxide
+ Water + Energy
Cellular Respiration Overview
Breakdown of glucose begins in the
cytoplasm: the liquid matrix inside
the cell
At this point life diverges into two
forms and two pathways
– Anaerobic cellular respiration (aka
fermentation)
– Aerobic cellular respiration
Section 9-1
Chemical Pathways
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without
oxygen)
Electron
transport
Alcohol or
lactic acid
Glycolysis
– Series of reactions which break the 6carbon glucose molecule down into two
3-carbon molecules called pyruvate
– Process is an ancient one-all organisms
from simple bacteria to humans perform
it the same way
– Yields 2 ATP molecules for every one
glucose molecule broken down
– Yields 2 NADH per glucose molecule
Gylcolysis
Section 9-1
Glucose
Glycolysis
2 Pyruvic acid
To the
electron
transport
chain
Fermentation
Releases energy from glucose without the
presence of oxygen.
There are two types of fermentation:
alcoholic and lactic acid.
Alcoholic fermentation is done by yeasts
and some microorganisms. It produces
alcohol & Carbon Dioxide
Lactic Acid is produced by muscles during
rapid exercise when the body cannot
supply enough oxygen.
Anaerobic Cellular Respiration
Some organisms thrive in environments with little
or no oxygen
– Marshes, bogs, gut of animals, sewage treatment ponds
No oxygen used= ‘an’aerobic
Results in no more ATP, final steps in these
pathways serve ONLY to regenerate NAD+ so it
can return to pick up more electrons and
hydrogens in glycolysis.
End products such as ethanol and CO2 (single cell
fungi (yeast) in beer/bread) or lactic acid
(muscle cells)
Section 9-1
Lactic Acid Fermentation
Glucose
Pyruvic acid
Lactic acid
Aerobic Cellular Respiration
Oxygen required=aerobic
2 more sets of reactions which occur
in a specialized structure within the
cell called the mitochondria
– 1. Kreb’s Cycle
– 2. Electron Transport Chain
Aerobic Cellular Respiration
Section 9-2
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
Cellular Respiration: An
Overview
Section 9-1
Mitochondrion
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Krebs
Cycle
Electrons
carried in
NADH and
FADH2
Electron
Transport
Chain
Mitochondrion
Cytoplasm
Aerobic Cellular Respiration
Oxygen required=aerobic
occur in a specialized structure
within the cell called the
mitochondria
– 1. Kreb’s Cycle
– 2. Electron Transport Chain
The Krebs Cycle
During the Krebs Cycle, pyruvic acid
is broken down into carbon dioxide in
a series of energy-extracting
reactions.
Citric Acid is created in this cycle
thus giving it the nickname Citric
Acid cycle.
Net ATP Production is 2 ATP.
Kreb’s Cycle
Completes the breakdown of glucose
– Takes the pyruvate (3-carbons) and breaks it
down, the carbon and oxygen atoms end up in
CO2 and H2O
– Hydrogens and electrons are stripped and
loaded onto NAD+ and FAD to produce NADH
and FADH2
Production of only 2 more ATP but loads
up the coenzymes with H+ and electrons
which move to the 3rd stage
Section 9-2
The Krebs Cycle
Citric Acid
Production
Mitochondrion
Electron Transport Chain
The electron transport chain uses the
high-energy electrons from the Krebs
Cycle to convert ADP to ATP.
Total ATP 32.
Electron Transport Chain
Electron carriers loaded with electrons and
protons from the Kreb’s cycle move to this
chain-like a series of steps (staircase).
As electrons drop down stairs, energy
released to form a total of 32 ATP
Oxygen waits at bottom of staircase, picks
up electrons and protons and in doing so
becomes water
Section 9-2
Electron Transport Chain
Electron Transport
Hydrogen Ion
Movement
Channel
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
Mitochondrion
ATP
Production
Energy Tally
36 ATP for aerobic vs. 2 ATP for
anaerobic
– Glycolysis
2 ATP
– Kreb’s
2 ATP
– Electron Transport
32 ATP
36 ATP
Anaerobic organisms can’t be too
energetic but are important for
global recycling of carbon
Energy & Exercise
Quick energy – Lactic Acid
fermentation is used to get quick
energy and gives off lactic acid as a
by product, thus the muscle pain.
Long-Term Energy – Use cellular
respiration to produce energy.
Exercising or activities that last for at
least 15 to 20 minutes. Best form for
weight control.
Comparing Photosynthesis &
Respiration
Photosynthesis
Cellular
Respiration
Function
Energy Storage
Location
Chloroplasts
Energy
Release
Mitochondria
Reactants
CO2 and H2O
Products
C6H12O6 and O2
C6H12O6 and
O2
CO2 and H2O
Equation
6CO2 + 6H2O 
C6H12O6 + 6O2
C6H12O6 + 6O2
6CO2 + 6H2O