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 Hoefnagels

Chapter 4, The Energy of Life, Pages 80-96
Chapter 6, How Cells Release Energy, Pages 120-132

Moodle

You may also ask questions and see answers to your classmates' questions in Moodle in the "Talk to Ed" forum.

Objectives:

The content of today's lecture will help you complete this assignment:

Take-Home Assignment #3 - Energy, Matter, Photosynthesis, and Respiration due at lecture Thursday, February 26.

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. 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.

Web Resources

• Adult Obesity

• Glycolysis animation from Smith College.

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

• Electron Transport animation from Smith College

Photosynthesis: Summary

Cellular Respiration - The Basic Reaction

The Chemical reactions of Photosynthesis and Respiration are facilitated by the action of protein molecules called ENZYMES Hoefnagels Pg. 87, fig. 4.10

    Protein: A polymer of amino acids

    Enzyme: A protein that catalyzes a chemical reation.

Overview of Cellular Respiration

• Hoefnagels Pg. 127, fig. 6.9

• What the heck is all this ATP used for, anyway???

• -cell movement (cilia and flagella movement)

• -muscle contraction

• -biosynthesis of macromolecules

• -enzyme function

• -transport of neurotransmitters between nerve cells

• -unwinding DNA double helix in replication

• -chromosome movement in cell division

• -ion transport in organelles

• -cytoplasmic streaming

• EVERYTHING

Glycolysis occurs in the cytoplasm.

• 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. from Hoefnagels Pg. 123, fig. 6.4

• Glucose Activation

• Enzyme Reactions

• Production of ATP & NADH (ENERGY)

• Production of Pyruvic Acid

• Glycolysis, the first 5 steps from Access Excellence

• Glycolysis, the last 5 steps from Access Excellence

Acetyl CoA Bridge to the Krebs Cycle

from Hoefnagels text Pg. 124. fig. 6.6

• 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.

• Krebs Cycle from Hoefnagels  Text, Pg. 125 figure 6.7

• Mitochondria from Hoefnagels  Text, Pg. 122 figure 6.3

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

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

• Acetyl CoA enters the Krebs cycle and combines with oxalic acid (4C) to produce citric acid (6C)

• Citric Acid is broken down step-by-step

• CO₂ is released

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

• oxalic acid (4C) is regenerated

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

The Respiratory Chain or Electron Transport Chain (ETC)

Hoefnagels Text Pg. 126, fig. 6.8

• 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)

• NADH ---> NAD+ releases electrons (e-)

• Electron (e-) flow produces a proton gradient

• O₂ accepts the electrons, combines with 2 H+ & produces H2O

• ATP synthase enzyme Text Pg. 135, fig. 8.11 B.

• ATP synthase animation (ENERGY)

• Model of ATP synthase in action
  from The Virtual Cell by Matej Lexa

Anaerobic Fermentation

Anaerobic Fermentation takes place in the absence of O₂ in the cytoplasm.

• Alcoholic Fermentation in plants and yeast

  Hoefnagels Text Pg. 130, fig. 6.12 a.

  • Pyruvic Acid converted to ethanol and CO₂

  • A small amount of ATP produced (ENERGY)

• Lactic Acid Fermentation in animals & some bacteria

  Hoefnagels Text Pg. 130, fig. 6.12 b.

  • 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

• Food as an energy source for respiration Hoefnagels text Pg. 128, fig. 6.10

• Illustrated tally of ATP produced Hoefnagels text Pg. 127, fig. 6.9

• Nitty-Gritty table of ATP produced

• Respiration as a source of raw materials for BIOSYNTHESIS from Access Excellence