Cellular Respiration (Chapter 9)

Cellular Respiration (Chapter 9)

Energy Plants, algae & some bacteria Convert radiant energy (sun) into

chemical energy (glucose)

Harvest Energy All activities an organism performs

requires energy

Catabolism Enzymes break down substances Harvest energy from C-H bonds Or other chemical bonds

Organic compounds + oxygen ⇨ Carbon Dioxide + water +

energy

Cellular respiration Aerobic respiration Chemical energy is harvested

from food Presence of oxygen Anaerobic respiration Process occurs without oxygen Fermentation

Anaerobic Glucose to lactate (muscle cells) Glucose to alcohol (yeast cells) Does not yield as much energy

Cellular respiration


C6H12O6 + 6 O2

---> 6 CO2 + 6 H2O + ATP

Cellular Respiration Exergonic -686kcal/mole (-2,870kJ/mole) Redox reaction Glucose is oxidized, oxygen is reduced Energy stored in glucose makes ATP 38 ATP generated ATP stores energy for use in cellular

functions

Vocabulary (Cell respire) NAD/NADH FAD ETC Phosphorylation Chemiosmosis ATP Synthase

NAD & NADH NAD: Nicotinamide adenine dinucleotide NAD+ oxidized form NADH reduced form NAD+ traps electrons from glucose Function as energy carrier

NAD & NADH Dehydrogenase (enzyme) Removes a pair of hydrogen atoms

from glucose Transfers one proton and 2

electrons to NAD+

H-C-OH + NAD+ ⇨ -C=O + NADH + H+

Used to make ATP

NAD & NADH

FAD Flavin adenine dinucleotide Transfers electrons

Electron transport chain Located inner membrane of

mitochondria Plasma membrane (prokaryotes) Series of molecules (mostly

proteins)

Electron transport chain Electrons fall to oxygen In a series of energy releasing

steps High potential energy to low Energy released generates ATP

Electron transport chain

Fre

e en

erg

y, G

Controlledrelease ofenergy for

synthesis ofATP

2 H+ + 2 e–

2 H + 1/2 O2

(from food via NADH)

ATP

ATP

ATP

1/2 O22 H+

2 e–E

lectron

transp

ort

chain

H2O

Phosphorylation Addition of a phosphate group to a

molecule ATP is formed by a

phosphorylation reaction 1. Substrate-level phosphorylation 2. Oxidative phosphorylation

Substrate phosphorylation Enzyme transfers

a phosphate from a organic substrate molecule

ADP to make ATP Direct formation Glycolysis and

Krebs cycle

Oxidation phosphorylation Energy from

electron transport chain

Synthesis ATP Adds an

inorganic phosphate to ADP

Chemiosmosis Energy-coupling mechanism Energy stored in hydrogen ion

gradient across membrane Makes ATP from ADP

ATP Synthase Enzyme helps make ATP Located in membrane Changes ADP to ATP Uses energy from a proton

gradient across membrane

The Reactions---Cell respire Glycolysis Krebs cycle (citric acid cycle) Electron transport chain (oxidative

phosphorylation)


Glycolysis Happens in cytoplasm Starts with glucose Yields 2 pyruvate (3 carbons)

molecules, 4 ATP (net of 2 ATP) & 2 NADH

10 enzyme catalyzed reactions to complete

Glycolysis Part one (priming) First 5 reactions are endergonic 2 ATP molecules attach 2

phosphate groups to the glucose Produces a 6 carbon molecule

with 2 high energy phosphates attached

Glycolysis Part two (cleavage reactions) 6 carbon molecule is split into 2 3-carbon molecules each with a

phosphate (G3P)

Glycolysis Part three (energy harvesting

reactions) In two reactions 2- G3P molecules

are changed to pyruvate 4 ATP molecules are made (net of

2) An energy rich hydrogen is

harvested as NADH (2NADH)

Glycolysis Every living organism can carry

out glycolysis Occur in aerobic & anaerobic Does not require oxygen Oxygen present the Krebs cycle

will begin

Fig. 9-9-1

ATP

ADP

Hexokinase1

ATP

ADP

Hexokinase1

Glucose

Glucose-6-phosphate

Glucose

Glucose-6-phosphate

Fig. 9-9-2

Hexokinase

ATP

ADP

1

Phosphoglucoisomerase2

Phosphogluco-isomerase

2

Glucose

Glucose-6-phosphate

Fructose-6-phosphate

Glucose-6-phosphate


1

Fig. 9-9-3

Hexokinase

ATP

ADP

Phosphoglucoisomerase

Phosphofructokinase

ATP

ADP

2

3

ATP

ADP

Phosphofructo-kinase

Fructose-1, 6-bisphosphate

Glucose

Glucose-6-phosphate



1

2

3


3

Fig. 9-9-4

Glucose

ATP

ADP

Hexokinase

Glucose-6-phosphate

Phosphoglucoisomerase


ATP

ADP

Phosphofructokinase


Aldolase

Isomerase

Dihydroxyacetonephosphate

Glyceraldehyde-3-phosphate

1

2

3

4

5

Aldolase

Isomerase


Dihydroxyacetonephosphate


4

5

Fig. 9-9-52 NAD+

NADH2

+ 2 H+

2

2 P i

Triose phosphatedehydrogenase

1, 3-Bisphosphoglycerate

6

2 NAD+



NADH2

+ 2 H+

2 P i


6

2

2

Fig. 9-9-62 NAD+

NADH2


+ 2 H+

2 P i

2

2 ADP


Phosphoglycerokinase2 ATP

2 3-Phosphoglycerate

6

7

2

2 ADP

2 ATP


3-Phosphoglycerate

Phosphoglycero-kinase

2

7

Fig. 9-9-7

3-Phosphoglycerate


2 NAD+

2 NADH+ 2 H+

2 P i

2

2 ADP

Phosphoglycerokinase


2 ATP

3-Phosphoglycerate2

Phosphoglyceromutase

2-Phosphoglycerate2

2-Phosphoglycerate2

2

Phosphoglycero-mutase

6

7

8

8

Fig. 9-9-82 NAD+

NADH2

2

2

2

2

+ 2 H+

Triose phosphatedehydrogenase2 P i



2 ADP

2 ATP

3-Phosphoglycerate


Enolase

2-Phosphoglycerate

2 H2O

Phosphoenolpyruvate

9

8

7

6

2 2-Phosphoglycerate

Enolase

2

2 H2O

Phosphoenolpyruvate

9

Fig. 9-9-9


2 NAD+

NADH2

2

2

2

2

2

2 ADP

2 ATP

Pyruvate

Pyruvate kinase

Phosphoenolpyruvate

Enolase2 H2O

2-Phosphoglycerate


3-Phosphoglycerate


2 ATP

2 ADP


+ 2 H+

6

7

8

9

10

2

2 ADP

2 ATP

Phosphoenolpyruvate

Pyruvate kinase

2 Pyruvate

10

2 P i

Oxidation of pyruvate Pyruvate is changed into acetyl-

CoA First carboxyl group is removed Leaves as carbon dioxide 2 carbon molecule called acetate

remains

Oxidation of pyruvate Pyruvate dehydrogenase Multienzyme complex Combines acetate (acetyl group)

with a coenzyme called coenzyme A.

Product is acetyl-CoA Plus one NADH

Oxidation of pyruvate Pyruvate dehydrogenase Largest known enzyme 60 subunits Process occurs within mitochondria Acetyl-CoA is end product of the

break down of fats and proteins too

Fig. 9-10

CYTOSOL MITOCHONDRION

NAD+ NADH + H+

2

1 3

Pyruvate

Transport protein

CO2Coenzyme A

Acetyl CoA

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Cellular Respiration (Chapter 9)