Transcript Respiration - Fort Thomas Independent Schools

Cellular Respiration:
Harvesting Chemical Energy
Respiration is the process of extracting
stored energy from glucose to make ATP.
Cellular Respiration Equation
C6H12O6 + 6 O2
6 CO2 + 6 H2O and energy
As a result of respiration, energy is released from the
chemical bonds found in complex organic molecules
(food).
Aerobic Respiration
• Aerobic Respiration is respiration which takes
place in the presence of oxygen
Respiration is controlled by Enzymes
…rate is controlled by enzymes
Cell Respiration
is divided into 3 stages.
(components)
1. Glycolysis
2. Krebs Cycle
3. Oxidative Phosphorylation
Glycolysis
• Glyco- glucose, -lysis: to split
• Universal step in all forms of respiration
• Likely used to supply energy for the ancient cells.
Glycolysis
• Function - To split glucose and
produce NADH, ATP and
Pyruvate (pyruvic acid).
• Location - Cytoplasm.
• Occurs in 9 steps…. 6 of the
steps use magnesium Mg as
cofactors.
NAD+
Energy carrier
• Nicotinamide Adenine Dinucleotide
NAD+ + 2 eNADH
NAD+ = oxidized form
NADH = reduced form
Requirements for Glycolysis
•
•
•
•
•
Glucose
2 ATP…. As activation energy
4 ADP
2 NAD+
Enzymes
The Products of Glycolysis
• 2 Pyruvic Acids (a 3C acid)
• 4 ATP
• 2 NADH
Net Energy Result
• 2 ATP per glucose
• 2 NADH
• In summary, glycolysis takes
one glucose and turns it into 2
pyruvate, 2 NADH and a net of
2 ATP.
Krebs Cycle
Also called: Citric Acid Cycle
or Tricarboxylic Acid Cycle
• Function: Oxidize pyruvic acid to CO2
• Produce: 3NADH, 1FADH2 and 1ATP
• Location: Mitochondria matrix
Formation of Acetyl CoA:
Acetyl CoA is formed when the pyruvate , from glycolysis,
combines with Coenzyme A… tis takes place in the matrix.
Requirements for Krebs Cycle
•
•
•
•
•
Pyruvic acid (3C acid)
Coenzyme A
3 NAD+
1 ADP
1 FAD
• Double this list for each glucose.
Products of Krebs Cycle
•
•
•
•
•
3 CO2
Acetyl CoA
3 NADH
1 ATP
1 FADH2
• Double this list for each glucose.
Krebs Cycle
• Produces most of the cell's
energy in the form of NADH
and FADH2… not ATP
• Does NOT require O2
• The CO2 produced by the Krebs
cycle is the CO2 animal exhale
when they breathe.
Oxidative Phosphorylation
• Process of extracting to energy from NADH and FADH2 to
form ATP.
• Function: Convert NADH and FADH2 into ATP.
• Location: Mitochondria cristae.
Oxidative Phosphorylation
• NADH or FADH2
• ADP
• O2
Oxidative Phosphorylation
• Requires the Electron Transport
Chain… the Electron Transport
Chain is a collection of
proteins, embedded in the
inner membrane, used to
transport the electrons from
NADH and FADH2
Cytochrome c
• Cytochrome c: is one of the
proteins of the electron transport
chain… often used by geneticists
to determine relatedness… exists
in all living organisms.
• The Cytochromes alternate
between RED and OX forms and
pass electrons down to O2
ATP Yield
• Each NADH energizes 3 ATP
• Each FADH2 energizes 2 ATP
Chemiosmotic Hypothesis
• ETC energy is used to move H+ (protons) across
the cristae membrane.
• ATP is generated as the H+ diffuse back into
the matrix through ATP Synthase
ATP Synthase
• Uses the flow of H+ to make ATP.
• Works like an ion pump in reverse, or like a
waterwheel under the flow of H+ “water”.
Alcoholic Fermentation
• Carried out by yeast, a kind of fungus.
Alcoholic Fermentation
• Uses only Glycolysis.
• An incomplete oxidation - energy is still left in the
products (alcohol).
• Does NOT require O2
• Produces ATP when O2 is not available.
Lactic Acid Fermentation
• Uses only Glycolysis.
• An incomplete oxidation - energy is still left in
the products (lactic acid).
• Does NOT require O2
• Produces ATP when O2 is not available.
Lactic Acid Fermentation
• Done by human muscle cells under oxygen
debt.
• Lactic Acid is a toxin and causes soreness and
stiffness in muscles.
Fermentation - Summary
• Way of using up NADH so Glycolysis can still
run.
• Provides ATP to a cell even when O2 is absent.
Aerobic vs Anaerobic
• Aerobic - Respiration with O2
• Anaerobic - Respiration without O2
• Aerobic - All three Respiration steps.
• Anaerobic - Glycolysis only.
Strict vs. Facultative
Respiration
• Strict - can only carry out Respiration one
way… aerobic or anaerobic.
• Facultative - can switch respiration types
depending on O2 availability. Ex - yeast
ATP yields by Respiration type
• Anaerobic - Glycolysis only
Gets 2 ATPs per glucose.
• Aerobic - Glycolysis, Krebs,
and Oxidative Phosphorylation
(electron transport chain)
Generates many more ATPs per
glucose.
Aerobic ATP yield
• Glycolysis - 2 ATPS, 2 NADHs
• Krebs - 2 ATPS, 8 NADHs,
FADH2
• Each NADH = 3 ATP
• Each FADH2 = 2 ATP
2
ATP Sum
• 10 NADH x 3 =
30 ATPs
• 2 FADH2 x 2 =
4 ATPs
• 2 ATPs (Gly) =
2 ATPs
• 2 ATPs (Krebs) = 2 ATPs
• Max = 38 ATPs per glucose
However...
• Some energy is used in shuttling the NADH
from Glycolysis into the mitochondria.
• Actual ATP yield ~ 36/glucose
Yeast
• Would rather do aerobic Respiration; it has 18x
more energy per glucose.
• But, anaerobic will keep you alive if oxygen is
not present.
Importance of fermentation
• Alcohol Industry - almost every society has a
fermented beverage.
• Baking Industry - many breads use yeast to
provide bubbles to raise the dough.
Summary
• Know the 3 main reactions of Respiration and
the 4 required items for each.