Cell Biology (288) -- Unit 8: Energy & Metabolism

Front 1

Metabolism:

Back 1

the sum of all chemical reactions in the cell.

Catabolis (releasing energy by breaking down things) vs. anabolis (consuming energy to build things)

Front 2

Cellular respiration:

Back 2

Glucose -(glycolysis)-> pyruvate -(oxidation)-> Acetyl CoA -(Krebs/TCA/citric acid)-> NADH -(electron transport chain)-> ATP

Front 3

ATP:

Back 3

the universal energy coupler-- drives most reactions. Has two very high-energy phosphoanhydride bonds: delta-G is approx. 7.3kcal/mol

Can act as phosphate donor to molecules with less energy than it-- easily generated from lesser molecules.

Front 4

Phosphoanhydride bonds:

Back 4

one bond has a delta-G of 3 or 4 kcal/mol. They are high in energy because they are created by bringing together two negative structures.

Front 5

Phosphoester bonds:

Back 5

lower in energy than phosphoanhydride bonds because they are created by bringing together a negative and a neutral structure.

Front 6

ATP hydrolysis in the cell:

Back 6

10-14 kcal/mol

Different cell types contain different concentrations of reactants and products, so the energy produced by ATP can vary.

High inorganic phosphate=high energy.

Front 7

Anaerobic conditions vs. aerobic conditions:

Back 7

Anaerobic: fermentable substrate --> lactate or ethanol+CO2

Aerobic: oxidizable substrate+O2 --> H2O+CO2

Front 8

Oxidation of glucose:

Back 8

C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O + energy (648 kcal/mol)

Front 9

Two phases of glycolysis:

Back 9

1) Input
2) Payoff

Front 10

Input phase:

Back 10

glucose + 2 ATP --> 2-glyceraldyhyde-3-P + 2 ADP + 2H+

a) glucose+1 ATP=irreversible phosphorylation-->glucose-6-phosphate
b) glucose-6-P-->fructose-6-P
c) fructose-6-P + 1 ATP=irreversible phosphorylation--> fructose-1,6-bisphosphate
d) fructose-1,6-bisphosphate= split into glyceraldehyde-3-P and dihydroxyacetone phosphate
e) dihydroxyacetone P converted into another glyceraldehyde-3-P

Front 11

Delta-G of an irreversible phosphorylation:

Back 11

Delta-G-naught (standard conditions): -4kcal/mol
Delta-G in vivo:
Input a)-8 kcal/mol
Input c)-5.3 kcal/mol

Front 12

Enzymes that catalyze reactions in the input phase:

Back 12

a) hexokinase
b) phosphoglucoisomerase
c) phosphofructokinase-1
d) aldolase
e) triose phosphate isomerate

Front 13

Payoff phase:

Back 13

a)glyceraldehyde-3-P + NAD+ --> 1,3-bisphosphoglycerate + NADH
b) 1,3-bisphosphoglycerate + 1 ADP --> 3-phosphoglycerate + 1 ATP
c) 3-phosphoglycerate --> 2-phosphoglycerate
d) 2-phosphoglycerate --> phosphoenolpyruvate (PEP) via dehydrogenation
e) PEP + (H+) + ADP --> pyruvate + ATP

Front 14

What is the pathway of pyruvate in anaerobic or aerobic conditions?

Back 14

Anaerobic: pyruvate + NADH + (H+) --> lactate + NAD+

Aerobic: pyruvate + (NAD+) + CoA--> Acetyl CoA + NADH + CO2

Front 15

How many times does payoff happen?

Back 15

TWICE! (Two molecules of glyceraldehyde-3-P produced by input phase.)

Front 16

Products of glycolysis:

Back 16

2 ATP, 2 NADH, 2 pyruvate

Front 17

Mitochondrial membranes:

Back 17

-outer membrane contains porins that allow rapid bulk movement of solutes between outer and intermembrane spaces, which are approximately at equilibrium

-inner membrane houses ATP synthases and transmembrane proteins of the ETC

Front 18

What creates the proton motive force in the mitochondria?

Back 18

The pumping of H+ across the inner membrane and into the mitochondrial matrix generates a H+ concentration gradient that creates the motive force.

Front 19

TCA cycle:

Back 19

oxidative decarboxylation of pyruvate

pyruvate--> acetyl CoA= 1 NADH, 1 CO2
Acetyl CoA -->oxidation= 1 ATP, 3 NADH, 1 FADH2, 2 CO2

Front 20

Electron transport chain:

Back 20

-oxidation of each NADH pumps 10 H+ (total 80-100 H+)
-oxidation of each FADH2 pumps 6 H+ (total 12 H+)

Front 21

Pyruvate to acetyl CoA:

Back 21

Oxidative decarboxylation:

pyruvate -(NAD+ to NADH; CoA-SH to CO2 via PDH)-> acetyl CoA

-HIGHLY exergonic
-free energy of release is transferred to thioester bond

Front 22

TCA-1:

Back 22

hydrolysis of thioester in acetyl-CoA drives condensation rxn and the formation of 6-C citrate (from 2-C acetate and 4-C oxaloacetate)

Front 23

TCA-2:

Back 23

switching of H-->OH creates isocitrate, with a rapidly oxidized hydroxyl group

Front 24

TCA-3:

Back 24

a) oxidation of hydroxyl on isocitrate= oxalosuccinate (and NAD+--> NADH)
b) decarboxylation of oxalosuccinate--> alpha-ketoglutarate

Front 25

TCA-4:

Back 25

oxidative decarboxylation of alpha-ketoglutarate--> succinyl-CoA (and NAD+ --> NADH; releases CO2)

Front 26

TCA-5:

Back 26

loss of CoA-SH drives formation of phosphoanhydride bond; creates GDP-->GTP (and GTP immediately used for ADP-->ATP)

Front 27

TCA-6:

Back 27

succinate oxidized to fumarate (FAD --> FADH2)

Front 28

TCA-7:

Back 28

hydration of fumarate to malate

Front 29

TCA-8:

Back 29

malate oxidized to oxaloacetate (NAD+ --> NADH and H+)

Front 30

Common electron carriers:

Back 30

1) Flavoproteins
2) Iron-sulfur proteins
3) Cytochromes
4) Copper-containing cytochromes
5) 2-step redox reaction of coenzyme Q (Ubiquinone)

Front 31

Transferring e- in the ETC:

Back 31

Complex I accepts e- from NADH
Complex II accepts from succinate
-both transfer e- to Coenzyme Q-->Complex III--> Complex IV--> O2

Front 32

Protons pumped by each complex in the ETC:

Back 32

Complex I: 4 H+
Complex II/CoQ: 2 H+
Complex III: 2 H+
Complex VI: 2 H+

Total: 10

Front 33

What happens when electrons move down the ETC?

Back 33

There is a reduction in free energy. That energy is used to pump protons against their concentration gradient, which creates a proton motive force that does work.

Front 34

ATP synthase:

Back 34

Has two complexes, F1 and F0.

Front 35

F0 complex:

Back 35

Positioned in the mitochondrial membrane. Contains the channel that protons flow through:
-a subunit, which has two proton half-channels, ten c subunits that form a ring that binds protons and rotates, and two b subunits that are static and join F0 to F1.

Front 36

F1 complex:

Back 36

3 alpha and 3 beta subunits, plus one delta, one epsilon, and one gamma.

Rotator: alpha subunits involved in ATP binding, beta subunits involved in catalysis
Delta links F1 and F0 via another subunit
Epsilon and gamma form the rotor that is linked to the c-ring

Front 37

How does the synthase move?

Back 37

1) Proton moves into one half-channel of the a subunit
2) Proton binds to one of 10 c subunits, pushing the c ring forward
3) Proton on the last c subunit pops out into the second a half-channel and exits the complex
4) One proton rotates the gamma subunit 120 degrees- 1/3 of a circle
5) The three faces of the asymmetrical gamma subunit push against the alpha-beta pairs of the rotator
6) Alpha-beta pairs change conformation: open, tight, or loose
7) After three protons have gone through (gamma rotor turned 360 degrees), the alpha-beta subunits have turned ADP+P into ATP