Download Chapter 9 - Cellular Respiration

Chapter 9:
CELLULAR RESPIRATION!!!
Mr. Freidhoff
Metabolism
• Metabolism: The set of chemical
reactions that occur in living
organisms in order to maintain
life.
–Anabolism: Building up
–Catabolism: Breaking down
Cellular Respiration
• Inputs:
–Glucose
–Oxygen
• Outputs:
–Carbon dioxide
–Water
–Energy (ATP)
Cellular Respiration Equation
C6H12O6 + 6O2  6CO2 + 6H2O + 38 ATP
Reactions
• Photosynthesis and Cellular Respiration are
opposite reactions.
Chemical Energy
• Form of potential energy.
• Chemical energy stored in
Carbohydrates is transferred to
ATP molecules.
• Energy also released by heat.
ATP Cycle
• ATP is recyclable.
• ADP and Phosphate group
can be restored to ATP.
– Input of energy
– Where?
• Foods
• ATP is “energy currency.”
• 10 million ATP can be
regenerated in 1 minute.
Aerobic vs. Anaerobic
• Aerobic Process:
Requires Oxygen.
– If no oxygen is
present, reaction
will NOT occur.
• Anaerobic Process:
Doesn’t require
oxygen.
Cellular Respiration
• Includes both aerobic and anaerobic
respiration but is often used to refer to
aerobic respiration.
NAD/NADH
• Each NADH represents stored energy.
• NADH passes the electrons to the
electron transport chain (ETC).
• NAD+ + H → NADH
• NAD+ are recyclable.
FAD/FADH2
• Different chemical formula than NAD+.
• Each FADH2 represents stored energy.
– Also transport electrons to ETC.
• FAD + H2 → FADH2
• FAD are recyclable.
Cellular Respiration 3 Steps
1.Glycolysis
2.Krebs Cycle
3.Electron Transport Chain
Glycolysis
• Glyco = sugar; lysis = breaking.
• Occurs in Cytoplasm.
• 1 glucose molecule gets broken down into 2
(three carbon) pyruvates.
– 2 ATP are used to break down glucose.
Glycolysis
• Produces 4 ATP, net of 2 ATP.
• Produces 2 NADH.
Glycolysis
• Inputs:
– Glucose
• Outputs:
– 2 NADH
– Net of 2 ATP.
– 2 pyruvate
molecules.
Oxidative decarboxylation
• AKA: The transition step.
• Small step between Glycolysis and Krebs Cycle.
– Occurs in mitochondria matrix.
• Converts Pyruvate (3C) to Acetyl CoA (2C).
• Requires oxygen to occur.
• Occurs twice.
– Why?
The Transition Step
• Inputs:
– 2 pyruvate
molecules (3C)
• Outputs:
– 2 Acetyl CoA (2C) *When you lose a carbon, it’s
always in the form of CO2
– 2 CO2
– 2 NADH
Krebs Cycle
• Also known as TCA or
Citric Acid Cycle.
• Discovered By Hans
Krebs.
• Cycle occurs twice for
every glucose
molecule.
– Why?
– You receive 2
Acetyl CoAs from
Transition step.
Krebs Cycle
Krebs Cycle
• Inputs:
–2 Acetyl CoA
• Outputs:
–6 NADH
–2 FADH2
–4 CO2
–2 ATP
• Occurs in the
mitochondrial matrix.
• Several enzymes
change compounds in
the cycle.
Electron Transport Chain
• Located at the Inner Mitochondrial Membrane.
• Inputs: 10 NADH and 2 FADH2.
• Where are the NADH and FADH2 molecules coming
from?
– Glycolysis and Krebs Cycle.
• Membrane proteins are binding sites for NADH and
FADH2.
Electron Transport Chain
• NADH and FADH2 molecules donate their
hydrogen ions and electrons at protein sites.
• Electrons travel through ETC.
• Hydrogen ions and electrons bond with
oxygen to form water.
– 6 H2O (Byproduct)
ATP SYNTHASE!!!
• Located in the membrane
of mitochondria.
• Bonds ADP and a
phosphate group to make
ATP.
• Powered by Hydrogen ions.
NADH and FADH2
• For every NADH molecule, 3 ATP are created.
– 10 NADH x 3 ATP = 30 ATP
• For every FADH2 molecule, 2 ATP are created.
– 2 FADH2 x 2 ATP = 4 ATP
• Total of 34 ATP created at the ETC.
– Most out of three steps.
Electron Transport
Hydrogen Ion Movement
Channel
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Energy Yield from Glucose Metabolism
Electrons carried
via NADH and
FADH2
Electrons
carried
via NADH
Citric
acid
cycle
Glycolysis
Pyruvate
Glucose
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Mitochondrion
Cytosol
ATP
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation
Mitochondria
• Inner membrane is
folded.
– Called Cristae
• What does this folding
give the mitochondria?
– More surface area.
• Why is that important?
– More and faster ATP
production.
– Evolutionary beneficial.
Mitochondria
• Found in plants and animals.
• DNA found in mitochondrial matrix, not nucleus.
• Mitochondrial DNA is passed down from mother to
offspring.
Mitochondria
• Mitochondria started out as single celled
prokaryotic cells.
• Billions of years ago, eukaryotic life engulfed
mitochondria and kept them around.
• Why was this an evolutionary advantage?
– Tons more ATP!
Anaerobic Respiration
• Not an efficient method of ATP
production.
• AKA: fermentation.
• Two primary types:
– Lactic Acid Fermentation
– Alcohol Fermentation
Lactic Acid Fermentation
• In muscle tissues during rapid and vigorous
exercise, muscle cells may be depleted of
oxygen.
• Muscles then switch from respiration to lacticacid fermentation.
Lactic Acid Fermentation
• Glycolysis is the only stage that occurs.
• Glucose  Pyruvate  Lactic acid + energy
• Notice that glycolysis doesn’t use Oxygen!
Alcohol Fermentation
• Occurs within some yeasts and bacteria.
• Creates products such as wines and beers.
• Fermentation also creates bread.
Yeasts
• Single celled fungi.
• Go through
fermentation by
breaking down
sugars and
producing CO2.
• Just one gram holds
about 25 billion
cells.
Why is fermentation important to
evolution?
• 3.5 billion years ago, there was no oxygen on
Earth.
• Organisms evolved around the atmosphere at
that time.
How efficient is cell respiration?
Energy released
from glucose
(as heat and light)
Energy released
from glucose
banked in ATP
Gasoline energy
converted to
movement
About
40%
25%
100%
Burning glucose
in an experiment
“Burning” glucose
in cellular respiration
Burning gasoline
in an auto engine
ATP Production
• Aerobic Respiration:
With Oxygen
• Steps
– Glycolysis: 2 ATP
– Krebs Cycle: 2 ATP
– Electron Transport
Chain: 34 ATP
• Total ATP: 38 ATP
• Products: CO2, H20
• Anaerobic Respiration:
Without Oxygen
• Steps
– Glycolysis: 2 ATP
• Total ATP Production: 2
ATP
• Products: Lactic Acid
How Is a Marathoner Different from a
Sprinter?
• Individuals inherit various percentages of the
two main types of muscle fibers, slow and
fast.
– The difference between the two is the process
each uses to make ATP.
– Slow fibers make it aerobically using oxygen.
– Fast fibers work anaerobically without oxygen.
How Is a Marathoner Different from a
Sprinter?
• The percentage of slow and fast muscle fibers
determines the difference between track
athletes.
– Those with a large percentage of slow fibers make
the best long-distance runners.
– Those with more fast fibers are good sprinters.