1. _____________________ and ________________ are catabolic, energy-yielding pathways

Complex molecule(High energy)

Simpler molecule(Low energy)

Enzyme+ heat + energy

Catabolic processes

1. ________________- to be discussed later

2 common types

2. ____________________-

•Organic compounds + O2 CO2 + H2O + Energy

Note: • This process uses _________.• This occurs in the _______________

CHAPTER 9CELLULAR RESPIRATION

•Organic compounds CO2 + H2O + Energy

• An example of cellular respiration- _____________ of glucose

C6H12O6 + 6O2 6CO2 + 6H2O + Energy (ATP + heat)Glucose

• An ________________reaction G = - 686 kcal per mole of glucose.

• Drives the generation of ATP from ADP

ATP then ____________________ other molecules, allowing them to do work

• _______ (reduction-oxidation) reactions- transfer of electrons from one reactant to another or changes bond type (single to double).

• The loss of electrons is called _____________.

• The addition of electrons is called _____________.

2. _______ reactions release ___________ when electrons move closer to _____________ atoms

• Example:

• NaCl Na+ + Cl-

• sodium is ____________and chlorine is ____________

• Na is the ____________________ and reduces Cl.

• Cl is the _____________________ and oxidizes Na.

• In the summary equation of cellular respiration: C6H12O6 + 6O2 6CO2 + 6H2O

• Glucose is ___________, oxygen is ____________, and electrons loose potential energy.

3. Electrons “fall” from organic molecules to ________ during cellular respiration

•At key steps, hydrogen atoms are stripped from glucose and passed first to a coenzyme, like NAD+ (nicotinamide adenine dinucleotide).

• Dehydrogenase enzymes strip two hydrogen atoms from the fuel (e.g., glucose), pass _______________ ________to NAD+ (to make NADH) and release H+.

• H-C-OH + NAD+ -> C=O + NADH + H+

Fig. 9.4

•NAD + functions as the __________________ in many of the redox steps during the catabolism of glucose.

•Energy is tapped to synthesize ATP as electrons “fall” from __________ to oxygen.

Fig. 9.5

• The________ ___________

_______ breaks the fall of electrons to __ into several steps.

• ________ shuttles electrons to the “top” of the chain.

• At the “bottom”, oxygen captures the ___________ and ___ to form water.

• The free energy change from “top” to “bottom” is ___ kcal/mole of NADH.

Energy used to make ATP!

1. Respiration involves glycolysis, the Krebs cycle, and electron transport

Fig. 9.6

1. __________(In cytoplasm)

2. ______________(in mitochondrial matrix)

3. ___________ ____________ (In inner mitochondrial membrane)

End result: ATP is generated

Glucose 2 Pyruvate 6 CO2

2 ADP 2 ATP 2 ADP 2 ATP

8 NADH2 NAD+ _________ 8 NAD+

2 FAD+ 2 FADH2

_____6 ADP 28 ADP _________

__________ ______

____________________

Add up total ATP generated : 2+2+6+28=___

• In the electron transport chain-

• the _________ move from molecule to molecule until they combine with oxygen and hydrogen ions to form __________.

• As they are passed along the chain, the energy carried by these electrons is stored in the mitochondrion in a form that can be used to synthesize ATP via _____________________________________.

• Oxidative phosphorylation produces almost ____ of the ATP generated by respiration.

Glucose 2 Pyruvate 6 CO2

2 ADP 2 ATP 2 ADP 2 ATP

These are generated by ______________________________

Enzyme•An _______ transfers a phosphate group from an organic molecule (the substrate) to ____, forming ____.

What is substrate level phosphorylation?

• Glucose, a six-carbon sugar, is split into two, 3-carbon sugars then into ________.

• Each of ___ steps in glycolysis is catalyzed by a specific _________.

2. Glycolysis

Divided into two phases: 1. an _______________

__________• 2 ATP used

2. an _____________ _________.• 4 ATP + 2 NADH

produced

Net = 2 ATP + 2 NADH

Fig. 9.9a

1st Phosphate groupadded

2nd Phosphate groupadded

Two 3-carbon molecules, each with one phosphate

Glycolysis Energy investment phase

Fig. 9.9b

2 PO4

1 PO4

0 PO4

Energy payoff phase

• If ___________ is present, pyruvate enters the _________________ where enzymes of the Krebs cycle complete the ______________ of the organic fuel to carbon dioxide.

3. The Krebs cycle completes the energy-yielding __________ of organic molecules

Glucose 2 Pyruvate 6 CO2

2 ADP 2 ATP 2 ADP 2 ATP

KrebsGlycolysis

What happens to pyruvate?

• Answer- Pyruvate is modified to ____________ which enters the Krebs cycle in the matrix.

• 1. A _______________ group is removed as CO2.

• 2. A pair of ______________ is transferred from the remaining two-carbon fragment to NAD+ to form NADH.

• 3. The oxidized fragment, acetate, combines with coenzyme A to form ___________

Fig. 9.10

• The Krebs cycle consists of ____ steps.

Fig. 9.12

• Each cycle produces

• one ATP by _____________ _____________• three ________• and one ______

Named after Hans Kreb – 1930s

• The conversion of pyruvate and the Krebs cycle produces large quantities of _______________.

Fig. 9.11

2 carbon atoms enter

2 carbon atoms released as CO2

Note the Krebs cycle is never depleted of ________: 2 in, 2 out

• Only __ of __ ATP produced by respiration of glucose are derived from ________________ ________________________.

• The vast majority of the ATP comes from the energy in the ________ carried by ______ (and ________).

4. The inner mitochondrial membrane couples _____________ to ATP synthesis

• Thousands of copies of the electron transport chain are found in the _________ (the inner membrane of the mitochondrion).

• Electrons drop in _____________ as they pass down the electron transport chain.

• Electrons carried by __________ are transferred to the first molecule in the electron transport chain, _____________________.

• The electrons continue along the chain which includes several ____________ proteins and one lipid carrier.

• The electrons carried by _____ have lower free energy and are added to a later point in the chain.

Fig. 9.13

•Electrons from NADH or FADH2 ultimately pass to oxygen.•The electron transport chain generates no ATP directly.

Note:

Electrons

• A protein complex, ___ _______, in the cristae actually makes ATP from ADP and Pi.

• ATP uses the energy of a _____________ (from the electron transport chain) to power ATP synthesis.

• This __________________ develops between the intermembrane space and the ________.

• Termed _______________ ______________________

Fig. 9.14

Then where does the ATP come from??

Fig. 9.15

• This coupling of the redox reactions of the electron transport chain to ______________ is called _____________________.

•In plants- light supplies the ____________•In bacteria, the H+ gradient is across the plasma membrane

• Most energy is from __________________________

5. Cellular respiration generates many ___ molecules for each _____ molecule it _________: a review

glucose NADH ET chain proton-motive force ATP

• A one six-carbon glucose molecule is oxidized to six CO2 molecules.

• Some ATP is produced by substrate-level phosphorylation

Fig. 9.16 Maximum yield is 38 ATP

• How efficient is respiration in generating ATP?

• Complete oxidation of glucose = _______ kcal/mole.

• Formation of each ATP requires = _____ kcal/mole.

• Efficiency of respiration is

• ____ kcal/mole x ___ ATP/glucose = ___%. 686 kcal/mole glucose

• The other approximately 60% is lost as ______.

• Cellular respiration is remarkably efficient in energy conversion.

• Oxidation refers to the loss of _______to any electron acceptor, not just to oxygen.

• In glycolysis, NAD+ is the ________ agent, not O2.

• Glycolysis generates _____ whether oxygen is present (aerobic) or not (anaerobic).

6. _____________ enables some cells to produce ATP without the use of _______

Fig. 9.17a

Problem- Fermentation (anaerobic catabolism) still requires NAD+ to accept electrons.

Solution-In _______________, NAD+ comes from the conversion of pyruvate to _________

• A second solution to the NAD+ problem:

• __________________________

• ( pyruvate is reduced directly by NADH to form ___________)

• Muscle cells switch from _________respiration to lactic acid ___________ to generate ATP when __ is scarce.

• The waste product, lactate causes muscle fatigue but ultimately it is converted back to pyruvate in the liver.

Fig. 9.17b

Compare respiration and fermentation

Respiration Fermentation

•Both use glycolysis to generate _______•Both use NAD+ as an _________________.

Similarities

Aerobic AnaerobicType

NAD+ regeneration

Organic molecules___

Energy yield

__ ATP___ ATP

• At a cellular level, human _________ cells can behave as facultative anaerobes, but ________ cells cannot.

• For facultative _________, pyruvate is a fork in the metabolic road that leads to two alternative routes.

Fig. 9.18

7. How do other ________________ fit into glycolysis and the Kreb cycle??

Answer- ____________ _____________ can all enter the pathway

•________ are degraded to amino acids, then deaminated (nitrogen secreted as urea, ammonia)

•______must be digested to glycerol and fatty acids.

•______________are broken down to glucose.

• Intermediaries in glycolysis and the Krebs cycle can be diverted to _____________ pathways.

• Examples:

• a human cell can synthesize about ______ the 20 different amino acids by modifying compounds from the _____________.

• ___________ can be synthesized from pyruvate and fatty acids from acetyl CoA.

• Excess carbohydrates and proteins can be converted to _______ through intermediaries of glycolysis and the Krebs cycle.

• Basic principles of ____________________ regulate the metabolic economy.

• If a cell has an excess of a certain amino acid, it typically uses feedback inhibition to prevent the diversion of more intermediary molecules from the Krebs cycle to the synthesis pathway of that amino acid.

• The rate of catabolism is also regulated, typically by the level of _________ in the cell.

• If ATP levels drop, catabolism speeds up to produce more ATP.

8. _____________________ control cellular respiration

• Control of catabolism is based mainly on regulating the activity of __________ at strategic points in the catabolic pathway.

• One strategic point occurs in the third step of glycolysis, catalyzed by ______________________

Fig. 9.20

•When ATP levels are high, inhibition of this enzyme slows ________________.

•_____________, the first product of the Krebs cycle, is also an inhibitor of phosphofructokinase.