Biology 100/101
Lecture 8: Respiration
(Print Version)

Announcements &
Assignments

Lecture Objectives

Web Resources

Photosynthesis
and Respiration

Overview of Cellular
Respiration

Glycolysis

Acetyl CoA
Bridge

Krebs Cycle

Electron
Transport Chain

Fermentation

Summary

Lecture Syllabus

IB 100/101 Home Page

Announcements & Assignments

Text Readings
in Lewis		 Test your Knowledge Questions Thinking Scientifically
Chapter 5, The Energy of Life
Chapter 7, How Cells Release Energy		 Page 96, Questions 10, 11, 12, and 13
Page 135, Questions 1, 2, 4, 5, 6, 7, and 8 		Page 96, questions 1, 2, 3, 4, & 5
Page 135, questions 1, 2, 3, & 4

The "Mastering Concepts" boxes are valuable summaries of the main ideas in these sections of the text.

Answers to many of these questions can be found at the Text On-Line Learning Center

You may also ask questions and see answers to your classmates' questions in Web Crossing in the "Talk to Jim, Ross and Ed" discussion.

Objectives:

After studying this material you should be able to:

  1. Explain how the process of respiration is involved in net primary production and an increase in plant biomass.

  2. Draw a diagram of part of a cell including a portion of cytoplasm and a mitochondrion and describe the energy transformations that occur in the cytoplasm and mitchondria as chemical energy from glucose and other compounds is converted to the chemical bond energy of ATP.

  3. List the inputs (raw materials) and outputs (products) of glycolysis, the Krebs Cycle, and the respiratory (electron transport) chain.

  4. Describe the roles of ADP, ATP, NAD+, NADH, and a proton gradient in the enzyme reactions of the Krebs Cycle and the respiratory (electron transport) chain.

  5. Explain where in the respiratory pathway O2 is used and CO2 is produced.

  6. Describe the role of oxygen in the process of aerobic respiration.

  7. Explain how weight loss and CO2 production are inseparably linked.

  8. Explain how proteins and fats may be utilized by the enzymes involved in respiration.

  9. Explain the role of the respiratory pathways in the processing of compounds for biosynthesis.

  10. Compare the energy output (in the form of ATP) of the anaerobic pathways (alcoholic and lactic acid fermentation) to that of aerobic respiration.

Respiration Links

Photosynthesis - The Basic Reaction

CO2 + H2O + Light Energy
Carbon Acceptor (RuBP)
Chloroplast Machinery		 ---> Simple
Sugars		 + O2

Respiration - The Basic Reaction

(Cellular) Respiration

O2 + Simple
Sugars		 ----> Usable
Chemical
Energy (ATP)		 + CO2 + H2O + HEAT

The Chemical reactions of Photosynthesis and Respiration are facilitated by the action of protein molecules called ENZYMES (Text, Pg. 94, fig. 5.16)

Overview of Cellular Respiration

from text Pg. 120. fig. 7.3

What the heck is all this ATP used for, anyway??? (text Pg. 120, table 7.1)

Glycolysis occurs in the cytoplasm.

from Profesor Emeritus Robert J. Huskey of The University of Virginia

...a simpler Glycolysis animation from Smith College.

Glycolysis "burns" glucose (6 carbons) to 2 molecules of pyruvic acid (3 carbons each) with a net gain of 2 ATP.(see Lewis, Pg. 122, fig. 7.5)

  • Glucose Activation

  • Enzyme Reactions

  • Production of ATP & NADH (ENERGY)

  • Production of Pyruvic Acid

Glycolysis from Text Pg. 122, fig. 7.5

Acetyl CoA Bridge to the Krebs Cycle

from text Pg. 122. fig. 7.6

  • The Pyruvic Acid molecules start to enter the mitochondria.

  • As it enters a mitochondrion a molecule of CO2 is split off the Pyruvic Acid molecule and the remaining two carbons are connected to a co-enzyme A molecule to produce Acetyl Coenzyme A (Acetyl CoA).

  • In the process, a molecule of NADH (ENERGY) is produced.

  • The Acetyl CoA actually enters the Krebs Cycle

    • Pyruvic
    Acid    		 + CoA + Enzyme
    Action    		 --> Acetyl
    CoA    		 + CO2 + NADH
    (ENERGY)

The Krebs Cycle occurs in the Mitochondria.

(Text, Pg. 124 figure 7.7)

Breakdown of carbohydrates to make short-term chemical energy (NADH, a little ATP, and FADH2).

  • Acetyl CoA enters cycle

  • Citric Acid broken down step-by-step

  • CO2 released

  • NADH, FADH2, and a little ATP is made (ENERGY)

  • 4C compound regenerated

The Krebs Cycle (AKA Citric Acid Cycle) from Access Excellence

Acetyl CoA and Krebs animation (AKA Citric Acid Cycle) from Smith College

The Respiratory Chain or Electron Transport Chain (ETC)

Text Pg. 126, fig. 7.9

Electron Transport animation from Smith College

ETC occurs on the mitochondrial inner membrane.
Conversion of NADH & FADH2 to lots and lots of ATP.
(see Lewis, fig. 7.9 and 7.10)

The Electron Transport Chain (ETC) from Prof. Huskey

Anaerobic Fermentation

Fermentation takes place in the absence of O2 in the cytoplasm. (see Lewis, figure 7.13)

  • Alcoholic Fermentation in plants and yeast

    • Text Pg. 132, fig. 7.13 c.

    • Pyruvic Acid converted to ethanol and CO2

    • A small amount of ATP produced (ENERGY)
  • Lactic Acid Fermentation in animals & some bacteria

    • Text Pg. 132, fig. 7.13 c.

    • Pyruvic Acid converted to Lactic Acid

    • A small amount of ATP is produced (ENERGY)

Anaerobic Breakdown of Pyruvate from Access Excellence

Summary of Energy Production