AP BIOLOGY OUTLINES - CHAPTER 6 - CELLULAR RESPIRATION HARVESTING CHEMICAL ENERGY
ABHI SANKA
CHAPTER 9 - CELLULAR RESPIRATION
HARVESTING CHEMICAL ENERGY
(pgs. 162 - 184)
CHAPTER NINE TARGETS
I.
II.
III.
Identify the basic chemical equation for aerobic cellular respiration.
Identify the main reaction sequences in the aerobic cellular respiration biological pathways.
Describe the location, function, reactants, products, and enzymatic actions for each aerobic cellular
respiration reaction in the pathway. Be able to summarize inputs and outputs for Glycolysis, Intermediate
Step (Bride Reaction), Krebs (Citric Acid) Cycle, and Electron Transport Chain including ATP production.
IV. Identify mathematical relationships describing conversions from one molecule to another.
V. Explain the chemiosmotic model for ATP generation.
VI. Describe the connection between Glycolysis and the fermentation reactions (alcoholic and lactic acid) in
anaerobic respiration. Describe the location, function, reactants, products, and enzymatic actions for each
step. Be able to summarize inputs and outputs for the entire anaerobic process including ATP Production.
VII. Contrast and compare aerobic and anaerobic respiration in terms of efficiency, location, inputs, outputs,
evolutionary history, and organism examples (eukaryote, prokaryote, different kingdoms).
VIII. Identify and explain the significance of redox reactions, oxidative phosphorylation, substrate-level
phosphorylation, decarboxylation, and hydrolysis in the biochemical pathways of aerobic cellular
respiration.
IX. Communicate the biological and commercial importance of respiration.
OVERVIEW: LIFE IS WORK
Chemical elements essential to life are recycled. (Waste products of respiration used for photosynthesis)
9.1
CATABOLIC PATHWAYS YIELD ENERGY BY OXIDIZING ORGANIC FUELS
CATABOLIC PATHWAYS AND PRODUCTION OF ATP
Aerobic Respiration - A catabolic pathway that consumes oxygen (O2) and organic molecules, producing ATP.
• The most efficient catabolic pathway carried out in most eukaryotic cells and many prokaryotic organisms.
• Anaerobic Respiration - harvest of chemical energy without using oxygen at all (some prokaryotic organisms)
Exergonic Degradation of Sugar Glucose (above) - C6H12O6 - fuel that cells most often use
Cellular Respiration - The catabolic pathways of aerobic and anaerobic respiration, which break down organic
molecules for the production of ATP.
Fermentation - partial degradation of sugar that occurs without use of oxygen
1
AP BIOLOGY OUTLINES - CHAPTER 6 - CELLULAR RESPIRATION HARVESTING CHEMICAL ENERGY
ABHI SANKA
REDOX REACTIONS: OXIDATION AND REDUCTION
The relocation of electrons releases energy stored in organic molecules ultimately used to synthesize ATP
Redox Reaction - A chemical reaction involving the
complete or partial transfer of one or more electrons
from one reactant to another; short for oxidationreduction reaction.
• Oxidation - loss of electrons from one substance
• Reduction - addition of electrons to another
substance
Reducing Agent - The electron donor in a redox
reaction. (Xe-) [Reduces Y, which accepts electron]
Oxidizing Agent - The electron acceptor in a recox
reaction. (Y) [Oxidizes (Xe-) by removing an electron]
• Not all redox reactions involve complete transfer of electrons (some change degree of electron sharing)
Oxidation of Organic Fuel Molecules During Cellular Respiration
• Glucose (fuel) is oxidized and oxygen is
reduced.
• Electrons lose potential energy, and energy is
released.
• Hydrogen abundant organic molecules excellent fuels (Hydrogen transferred above)
• Main energy foods: carbohydrates/fats - reservoirs of electrons associated with hydrogen
Stepwise Energy Harvest via NAD+ and the Electron Transport Chain
NAD+ - Nicotinamide adenine dinucleotide: coenzyme that can accept an electron and acts as an electron carrier
in the electron transport chain. (functions as an oxidizing agent during respiration)
2
• Most versatile electron acceptor in cellular
respiration and functions in several redox
steps during the breakdown of glucose
AP BIOLOGY OUTLINES - CHAPTER 6 - CELLULAR RESPIRATION HARVESTING CHEMICAL ENERGY
ABHI SANKA
Electron Transport Chain - A
sequence of electron carrier
molecules (membrane proteins)
that shuttle electrons during the
redox reactions that release
energy used to make ATP.
• Means in which electrons that
are extracted from glucose and
stored as potential energy in
NADH reach Oxygen
• Consists of a number of
molecules, mainly proteins, built
into the inner membrane of
mitochondria of eukaryotic cells
and the plasma membrane of
aerobically respiring prokaryotes
• Electrons removed from glucose
by NAD+ fall down an energy
gradient in the electron
transport chain to a far more
stable location in the
electronegative oxygen atom
Summary of “Downhill Route”: glucose ➔ NADH ➔ electron transport chain ➔ oxygen.
THE STAGES OF CELLULAR RESPIRATION: A PREVIEW
1.
2.
3.
Glycolysis
The Citric Acid Cycle
Oxidative Phosphorylation: electron transport and chemiostasis
3
AP BIOLOGY OUTLINES - CHAPTER 6 - CELLULAR RESPIRATION HARVESTING CHEMICAL ENERGY
ABHI SANKA
First two stages of cellular respiration: Glycolysis and the citric acid cycle are the catabolic pathways that break
down glucose and other organic fuels
Glycolysis - The splitting of glucose into two compounds called pyruvate. (occurs in cytosol)
• Occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration.
Citric Acid Cycle - the second major stage in cellular respiration involving eight steps that complete the
metabolic breakdown of glucose molecules begun in glycolysis by oxidizing pyruvate to carbon dioxide
• Carbon Dioxide represents fragments of oxidized organic molecules
• Occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes
In third stage of respiration, the electron transport chain accepts electrons from the breakdown products of the
first two stages and passes these electrons from one molecule to another.
Oxidative Phosphorylation - the third major stage of cellular respiration; the production of ATP using energy
derived from the redox reactions of an electron transport chain
• Accounts for 90% of ATP generated in respiration (small amounts generated by glycolysis/citric acid cycle)
• Stored in mitochondrion
Substrate-level Phosphorylation - mode of ATP
synthesis that occurs when an enzyme transfers a
phosphate group from a substrate molecule to
ADP, rather than adding an inorganic phosphate
to ADP as in oxidative phosphorylation
4