Cellular RespirationChapter 9

Objectives:3.0 Identify reactants and products associated with

photosynthesis and cellular respiration and the purposes of these two processes.

AOD B.3.1 Identify the function of photosynthesis and cellular respiration.

AOD B.3.2 Describe photosynthesis and cellular respiration, including their reactants and products.

AOD B.3.3 Recognize the relationship between reactants and products associated with photosynthesis and cellular

respiration. AOD B.3.4 Recognize a given formula as either

photosynthesis or cellular respiration.

Overview

Fill in the major steps in cellular respiration while watching the following video clip: http://www.youtube.com/watch?v=aXC9jMNIRnE

Section 9-1• What is the function of the

mitochondria?• What types of cells contain

mitochondria?All eukaryotic cells

Source: http://adamsewall.com/blog/happy-mitochondria-happy-gonads/629/

• Mitochondria release the energy from glucose and other food compounds.

• Step 1: Glycolysis• Step 2:

– If glycolysis takes place in the presence of oxygen, then the Kreb’s cycle and electron transport chain work to produce lots of ATP.

– Without oxygen, fermentation occurs.

• Made up of all three processes: glycolysis, Kreb’s cycle, and electron transport chain

• Occurs in the presence of oxygen

C6H12O6 + 6O2 6CO2 + 6H2O + energy

• Glucose, if converted all at once, would set the cells on fire!

Cellular Respiration

Glycolysis• Breaks 1 glucose molecule in

half, producing 2 molecules of pyruvic acid (a 6-carbon molecule becomes 2 3-carbon molecules).

• Requires 2 molecules of ATP to break the glucose molecule.

• At the end, the cell will have 4 ATP molecules --- a gain of 2

NADH Production in Glycolysis• 4 high-energy electrons and 2

H+’s attach to 2 electron carriers called NAD+ (comparable to NADP+ in photosynthesis), converting it into NADH.

• Glysolysis yields low energy amounts, but extremely rapidly, and with or without oxygen.

Overview/Review

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20lectures/cellular%20respiration/cellular.htm

• Releases energy from food particles by producing ATP in the absence of oxygen.

• Cells convert NADH back to NAD+ by passing electrons back to pyruvic acid. This allows glycolysis to continue producing ATP.

Fermentation (“Anaerobic Respiration”)

2 Types of Fermentation:1. Alcoholic fermentation

– Yields ethyl alcohol and CO2 – Pyruvic acid + NADH

alcohol + CO2 + NAD+ – What types of cells?

2. Lactic acid fermentation– Yields lactic acid– Pyruvic acid + NADH lactic

acid + NAD+ – What types of cells?

Bellringer/Assessment• Refer to the “Overview/Review”

for glycolysis, and Figures 9-3 and 9-4, as needed, to create a simple flowchart for:1. Glycolysis2. Alcoholic fermentation3. Lactic acid fermentation

• (Remember, flowchart instructions/example are found on p.1065)

Section 9-2• What are the “waste” products

of cellular respiration?• How do we get rid of these

waste products?• Quick Lab: How does exercise

affect disposal of wastes from cellular respiration? (p.231)

Section 9-2• The aerobic (“in air” – or

oxygen) pathway after glycolysis consists of 2 main portions:1. The Kreb’s cycle2. The electron transport chain

Kreb’s Cycle

• Discovered by Hans Krebs in 1937.

• Breaks pyruvic acid (from where???) into (ultimately) carbon dioxide

Kreb’s Cycle Steps1. Pyruvic acid enters the

mitochondrion.2. One carbon atom breaks off

and forms carbon dioxide. The other 2 carbon atoms, 1 oxygen atom, and 3 hydrogen atoms form an acetyl group that attaches to coenzyme A to form acetyl-CoA.

Kreb’s Cycle Steps3. Acetyl-CoA adds the acetyl

group to a 4-carbon molecule, forming a 6-carbon citric acid molecule. (This is why it is also called the citric acid cycle.)

4. 2 carbons are removed (individually) to form CO2, and electrons are added to energy carrier molecules (???).

Kreb’s Cycle Steps5. After 2 carbons have been

removed, how many carbons are left?

This 4-carbon molecule is now ready to accept another acetyl group.

Kreb’s Cycle Steps6. For each cycle, an ATP

molecule is produced --- as citric acid is being reduced to a 4-carbon molecule.

7. Additionally, 5 pairs of high-energy electrons are transferred to electron carriers, changing NAD+ to ??? and FAD to FADH2.

Kreb’s Cycle Products

• CO2

• ATP• NADH and FADH2

• What happens to each of these products?

Electron Transport Chain• So what do you think happens

here?Electrons from the Kreb’s cycle

are used to convert ADP to ATP.

• How do electrons get from the Kreb’s cycle to the transport chain?

Attached to NADH and FADH2

• NADH and FADH2 release H+’s and electrons.

• The electrons are passed down the transport chain until they join with oxygen and H+’s to form water (H2O).

• Every time 2 electrons are transported down the chain, a H+ is transported across the membrane.

• How do the H+’s generate energy for the cell?

1.They cross ATP synthase to reestablish an equilibrium of charges, and convert ADP to ATP.

2.They join with oxygen and electrons to form water (H2O).

• What happens to the NADH and FADH2?

Converted to NAD+ and FAD to be reused (where????).

Total Production• Glycolysis = 2 ATP• This is ALL the ATP produced

without oxygen.• WITH oxygen:

– Kreb’s cycle + electron transport chain = 34 ATP

– Total = 36 ATP ---- 18x more than anaerobic respiration!!!!

Comparing Photosynthesis and Cellular Respiration

Photosynthesis Cellular RespirationFunctionLocationReactantsProductsEquation