Inner FireHow Living Beings Get Energy From Food

Cristian Dinu

Technical and Scientific Writing

May 15th, 2012

Apr 15, 2012 TSW Presentation 2

Food!

Apr 15, 2012 TSW Presentation 3

Food!

Sugars

Fats

Protein

Minerals

Apr 15, 2012 TSW Presentation 4

We Burn Sugars and Fats

Sugars

Fats

Apr 15, 2012 TSW Presentation 5

We Burn Sugars and Fats

Sugars

Fats

Apr 15, 2012 TSW Presentation 6

The Problem With Combustion● Energy released too quickly

Apr 15, 2012 TSW Presentation 7

The Problem With Combustion● Would you release the energy in a gas tank...

...in 10 hours?

Apr 15, 2012 TSW Presentation 8

The Problem With Combustion● Would you release the energy in a gas tank...

...in 10 hours? ...or 10 seconds?

Apr 15, 2012 TSW Presentation 9

The Problem With Combustion● Energy released too easily● Hard to control who gets in and out of the

reaction● Bad idea in an environment loaded with chemicals

● Generates mainly heat and physical force● Not easily used by the cell

– You can't put pistons and turbines in there!● How do you transmit and store the energy?

Apr 15, 2012 TSW Presentation 10

The Problem With Combustion● Energy released too easily● Hard to control who gets in and out of the

reaction● Bad idea in an environment loaded with chemicals

● Generates mainly heat and physical force● Not easily used by the cell

– You can't put pistons and turbines in there!● How do you transmit and store the energy?

Apr 15, 2012 TSW Presentation 11

Storage and Transmission

Nuclear reactor● Generates heat

PC● Toggles gates

● Spins fans● Emits light

Apr 15, 2012 TSW Presentation 12

Storage and Transmission

Turbine

Electricity

Apr 15, 2012 TSW Presentation 13

Enter the Dragon

Adenosine Triphosphate (ATP)Universal Energy Carrier

Apr 15, 2012 TSW Presentation 14

Enter the Dragon

Adenosine Triphosphate (ATP)Universal Energy Carrier

Adenosine

Ribose

PhosphateGroup

Apr 15, 2012 TSW Presentation 15

How ATP works

Adenosine Triphosphate(ATP)

Adenosine Diphosphate(ADP)

Charged Spent

Apr 15, 2012 TSW Presentation 16

How ATP works● Energy is stored in the bond to the last

phosphate group● Allows other reactions to occur by breaking this

bond● Chemical energy → very versatile!

● Must be “recharged” by reattaching the phosphate group● ATP → ADP + PG + energy● ADP + PG + energy → ATP

Apr 15, 2012 TSW Presentation 17

Step 1: Preparations

Other sugars(e.g. sucrose)

Fats“gzipped sugars”

Glucose

Conversion

Apr 15, 2012 TSW Presentation 18

Step 2: Glycolysis

Glucose

2 x Pyruvate

10 steps

2 x ATP

2 x ADP

Investment

Payoff2 x ADP2 x NAD+

2 x ATP2 x NADH

Apr 15, 2012 TSW Presentation 19

Step 2: Glycolysis● Performed directly by the cell

● Before mytochondria were “invented”

● Net gain: 2 ADP / glucose molecule● Simpler organisms stop here● Next steps performed by mytochondria in more

advanced organisms:● Krebs cycle● Electron transport chain

Apr 15, 2012 TSW Presentation 20

Step 3: The Krebs Cycle● 9 stages● Pyruvate is gradually

dismantled● Net outcome:

● 4 x NAD+ → 4 x NADH

● 1 x FAD → 1 x FADH2

● 1 x ADP → 1 x ATP

● Pyruvate → 3 x CO2

Apr 15, 2012 TSW Presentation 21

Step 4: The e- Transport Chain● Electron in NADH: high

energy● Electron in O2: low

energy● Break electron's fall to

extract energy● Net outcome:

● 1 x NADH → 1 x NAD+

● 3 x ADP → 3 x ATP

● O2 → H

2O

Apr 15, 2012 TSW Presentation 22

Final Analysis● 1 glucose molecule → 36 ATP's recharged● Remarkable efficiency: 38%

● Gasoline engines barely achieve 25%

● Connected to many other metabolic pathways not listed here

● Definitely not compliant to Unix philosophy!

Apr 15, 2012 TSW Presentation 23

Conclusions● We do not really

“burn” sugars & fats● Highly sophisticated

process● A sort of “abstraction

layer” for combustion

● Biology is awesome!

● Thank you!