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Living organisms obtain energy by breaking down organic molecules during cellular respiration.
Section 3: Cellular Respiration
KWhat I Know
WWhat I Want to Find Out
LWhat I Learned
• 9(B) Compare the reactants and products of photosynthesis and cellular respiration in terms of energy and matter.
• 2(G) Analyze, evaluate, make inferences, and predict trends from data.
• 3(A) In all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student.
• 4(A) Compare and contrast prokaryotic and eukaryotic cells.• 4(B) Investigate and explain cellular processes, including homeostasis,
energy conversions, transport of molecules, and synthesis of new molecules.
• 9(D) Analyze and evaluate the evidence regarding formation of simple organic molecules and their organization into long complex molecules having information such as the DNA molecule for self-replicating life.
Cellular RespirationCopyright © McGraw-Hill Education
Essential Questions• What are the stages of cellular respiration?• What is the role of electron carriers in each stage of cellular
respiration?• What are the similarities between alcoholic fermentation and lactic
acid fermentation?
Cellular RespirationCopyright © McGraw-Hill Education
Review• cyanobacterium
New• anaerobic process• aerobic respiration• aerobic process• glycolysis• Krebs cycle• fermentation
Cellular RespirationCopyright © McGraw-Hill Education
Vocabulary
Overview of Cellular Respiration• Organisms obtain energy in a process called cellular respiration.
• Respiration harvests electrons from organic molecules and uses the energy to make ATP.
• The equation for cellular respiration is the opposite of the equation for photosynthesis:
Cellular RespirationCopyright © McGraw-Hill Education
Overview of Cellular Respiration • Cellular respiration occurs in two main parts: glycolysis and aerobic
respiration.
• Glycolysis is an anaerobic process, meaning it does not require oxygen.
• Aerobic respiration involves the Krebs cycle and electron transport.
• Aerobic processes require oxygen.
Cellular RespirationCopyright © McGraw-Hill Education
Glycolysis• Glucose is broken down in the
cytoplasm through the process of glycolysis.
• Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.
Cellular RespirationCopyright © McGraw-Hill Education
Krebs Cycle• Glycolysis has a net result of two ATP and two pyruvate.
• Most of the energy from the glucose is still contained in the pyruvate.
• In the presence of oxygen, pyruvate is transported into the mitochondrial matrix, where it is converted into carbon dioxide.
• The series of reactions in which pyruvate is broken down into carbon dioxide is the Krebs cycle, also know as the tricarboxylic acid (TCA) cycle
Cellular RespirationCopyright © McGraw-Hill Education
Krebs Cycle
Steps of the Krebs cycle• Prior to the Krebs cycle,
pyruvate reacts with coenzyme A (CoA) to form acetyl CoA.
• Acetyl CoA moves into the mitochondrial matrix.
• Acetyl CoA combines with a 4-carbon compound to form citric acid.
Cellular RespirationCopyright © McGraw-Hill Education
Krebs Cycle
Steps of the Krebs cycle• Citric acid is broken down
releasing two molecules of carbon dioxide and generating one ATP, three NADH, and one FADH2.
• Finally, acetyl CoA and citric acid are generated and the cycle continues.
Cellular RespirationCopyright © McGraw-Hill Education
Krebs Cycle
Animation
FPOAdd link to concepts animation from page 230 (Figure 13) here.
Cellular RespirationCopyright © McGraw-Hill Education
Electron Transport• In aerobic respiration, electron transport is the final step in the
breakdown of glucose.
• NADH and FADH2 from the Krebs cycle are used to convert ADP to ATP.
• Electron transport and chemiosmosis in aerobic respiration are similar to the processes of photosynthesis.
Cellular RespirationCopyright © McGraw-Hill Education
Electron Transport
Prokaryotic cellular respiration• Some prokaryotes undergo aerobic respiration.
• They do not have mitochondria, so they use the cellular membrane as the location of electron transport.
Cellular RespirationCopyright © McGraw-Hill Education
Anaerobic Respiration• When oxygen is unavailable, cells cannot follow glycolysis with the
aerobic respiration (Krebs cycle and electron transport).• The anaerobic process that follows glycolysis is anaerobic
respiration, or fermentation.• Fermentation occurs in the cytoplasm of the cell, and produces
NAD+ and ATP.
Cellular RespirationCopyright © McGraw-Hill Education
Anaerobic Respiration
Lactic acid fermentation• Enzymes convert the pyruvate made during glycolysis into lactic
acid.
• Skeletal muscles produce lactic acid when the body cannot supply enough oxygen, such as during periods of strenuous exercise.
Cellular RespirationCopyright © McGraw-Hill Education
Anaerobic Respiration
Alcohol fermentation • Occurs in yeast and some bacteria
• Converts pyruvate into ethyl alcohol and carbon dioxide
Cellular RespirationCopyright © McGraw-Hill Education
Photosynthesis and Cellular Respiration
Cellular RespirationCopyright © McGraw-Hill Education
Virtual Lab – Cellular Respiration
Concepts in Motion
FPOAdd link to concepts in motion interactive table from page 232 here.
Cellular RespirationCopyright © McGraw-Hill Education
BrainPOP – Photosynthesis & Cellular Respiration
Concepts in Motion
FPOAdd link to concepts in motion interactive table from page 233 here.
Cellular RespirationCopyright © McGraw-Hill Education
Cellular RespirationCopyright © McGraw-Hill Education
Review
Essential Questions• What are the stages of cellular respiration?• What is the role of electron carriers in each stage of cellular
respiration?• What are the similarities between alcoholic fermentation and lactic
acid fermentation?
Vocabulary • Krebs cycle• fermentation
• anaerobic process• aerobic respiration
• aerobic process• glycolysis
