EXAM #1 RESULTS90-100 = 3 students80-89 = 5 students70-79 = 7 students60-69 = 3 students

50*-60 = 2 students*No one got below a 50

1 students did not take the test

0

2

4

6

8

90-100 80-89 70-79 60-69 50-59

How would you rate the quality of this course so far?

• 18 completed; 2 not completes

– Average was 8.5

• Comments:

– “Lab to get better”

– “When presenting the material going a little more in depth with typical examples would improve my learning skills……”

– “Would be better if recently taken chemistry”

– “I would like the lecture to go a little slower so I can copy the lecture notes”

Comments cont.

• “I like the overhead powerpoint presentations”• “Slow down a little bit”• “Better coordination between lab and lecture”• “I like the video clips”• “Sync with lab”• “I like all the material posted on the web. It makes

it easy to study”• “Make lectures more interactive – I like the group

Quizzes”

Review Ch. 6

• Group Question/Answer Session

Chapter 9

Biology

Cellular Respiration

• 1. Cellular respiration includes the various metabolic pathways that break down carbohydrates and other metabolites and build up ATP.

• 2. Aerobic respiration begins with glucose and oxygen, and ends with CO2 and H2O.

Organic Compound + Oxygen ----> Carbon Dioxide + Water + Energy

Chemistry Fire Oxidation Respiration

Origin of Life Oxygen

Redox Reactions

• Based on the transfer of electrons during the chemical reaction.

• The relocation of electrons release the energy stored in food molecules, and this energy is used to synthesize ATP.

• These electron transfers are called oxidation-reduction reactions (redox reactions).

– The loss of electrons from one substance is called oxidation

– The addition of electrons to another substance is called reduction (reduce the amount of positive charge)

B. NAD+ Is a Carrier of Electrons

• Electrons received by NAD+ and FAD are high-energy electrons and are carried to the electron transport system.

C. Metabolic Pathways Are Required

• Glycolysis is the breakdown of glucose to two molecules of pyruvate.

• 1) Enough energy is released for immediate buildup of two ATP.

• 2) Glycolysis takes place outside the mitochondria and does not utilize oxygen.

C. Metabolic Pathways Are Required

• The Transition Reaction: pyruvate is oxidized to an acetyl group and CO2 is removed.

C. Metabolic Pathways Are Required

• The Krebs Cycle

• 1) This series of reactions gives off CO2 and produces ATP.

• 2) Produces two immediate ATP molecules per glucose molecule.

C. Metabolic Pathways Are Required

• The Electron Transport System

• 1) Series of carriers accepts electrons from glucose; electrons are passed from carrier to carrier until received by oxygen.

• 2) Electrons pass from higher to lower energy states, energy is released and stored for ATP production.

• 3) Oxygen (O2) is reduced to water (H2O).

Outside the Mitochondria: Glycolysis

A. Glycolysis:

• 1. Occurs in the cytosol outside the mitochondria.

• 2. The breakdown of glucose to 2 pyruvate molecules.

• 3. Universal in organisms; therefore, most likely evolved before Krebs cycle and electron transport system.

B. Energy Investment Steps

• 1. Glycolysis begins with addition of 2 phosphate groups, activating glucose to react.

• 2. Two separate reactions use 2 ATP.

• 3. Glucose, a C6 molecule, splits into two C3 molecules, each with a phosphate group.

C. Energy Harvesting Steps

• Substrate Level Phosphorylation

Glycolysis Mambo

• Do not let the chemical details block your view of glycolysis as a source of ATP and NADH

• Just sing!

Inside the Mitochondria: Completion of Aerobic

Respiration

• Pyruvate enters mitochondria.

A. Aerobic Respiration:

• 1. Involves the Transition reaction, the Krebs cycle, and the Electron transport system.

• 2. Process in which pyruvate from glycolysis is broken down completely to CO2 and H2O.

• 3. Takes place inside mitochondria.

C. Transition Reaction Releases CO2

• 1. Transition reaction connects glycolysis to the Krebs cycle.

• 2. In this reaction, pyruvate is converted to a two-carbon acetyl group attached to coenzyme A.

C. Transition Reaction Releases CO2

• 3. This oxidation reaction removes electrons from pyruvate by dehydrogenase using NAD+ as coenzyme.

• 4. Reaction occurs twice for each original glucose molecule.

D. The Krebs Cycle Finishes Glucose Breakdown

• 1. Krebs cycle reactions occur in matrix of mitochondria.

• 2. Cycle is named for Sir Hans Krebs, who received Nobel Prize for identifying these reactions.

• 3. Cycle begins by adding C2 acetyl group to C4 molecule, forming citrate; also called the citric acid cycle.

Respiration-Asthma

E. The Electron Transport System Produces Most ATP

• Electron transport system is located in cristae of mitochondria; consists of carriers that pass electrons.

• Oxygen serves as terminal electron acceptor and combines with hydrogen ions to form water.

• Because O2 must be present for system to work, it is called oxidative phosphorylation.

Respiration ETS

How Efficient is Aerobic Respiration?

• a. Glucose + O2 => CO2 + H2O

– 686 kcal (bomb calorimeter)

• b. ATP phosphate bond

– 7.3 kcal x 36 ATP = 263 kcal.

• c. Efficiency is 263/686

– 40% of available energy in glucose is transferred to ATP.

Fermentation

Cellular Respiration Includes Fermentation

Fermentation consists of glycolysis plus reduction of pyruvate to either lactate or alcohol and CO2.

Occurs when oxygen is not readily available.

A. Cellular Respiration Includes Fermentation

• a. Anaerobic bacteria produce lactic acid when we manufacture some cheeses.

• b. Anaerobic bacteria produce industrial chemicals: isopropanol, acetic acid.

• c. Yeasts produce alcohol in winemaking.

• d. Animals reduce pyruvate to lactate when it is produced faster than it can be oxidized by Krebs cycle.

Bacterial Applications

B. Advantages and Disadvantages of Fermentation

• 1. Despite low yield of two ATP molecules, fermentation provides quick burst of ATP energy for muscular activity.

• 2. Disadvantage is that lactate is toxic to cells.

– When blood cannot remove all lactate from muscles, lactate changes pH and causes muscles to fatigue.

C. How Efficient Is Fermentation?

• 1. Two ATP produced per glucose

– 14.6 kcal.

• 2. Complete glucose breakdown

– 686 kcal. of energy.

• 3. Efficiency for fermentation is 14.6/686

– 2 % - much less than complete breakdown of glucose.

Genetics of Alcoholism

Metabolism

1. Catabolism: Breaking Down

2. Anabolism: Building Up

B. Catabolism: Breaking Down

• 1. Glucose is broken down in cellular respiration

• 2. Fat breaks down into glycerol and three fatty acids.

• 3. Proteins (amino acids) break down into carbon chains and amino groups (urea).

B. Catabolism: Breaking Down

• b. An 18-carbon fatty acid is converted to nine acetyl-CoA molecules that enter the Krebs cycle.

• c. Respiration of fat products can produce 109 ATP molecules; fats are efficient form of stored energy.

Calories• Fat contains 9 calories per gram

• Protein contains 4 calories/gram

• Carbohydrates has 5 calories per gram

• (approximately)

C. Anabolism: Building Up

• ATP produced during catabolism drives anabolism.

• Excess carbohydrates energy can result in fat synthesis.

C. Anabolism: Building Up

• Plants synthesize all amino acids they need; animals lack some enzymes needed to make some amino acids.

• Humans synthesize 11 of 20 amino acids; remaining 9 essential amino acids must be provided by diet.

The End.