Energy is never created or destroyed, only transformed Entropy (disorder) increases

Laws of thermodynamics

Convert energy source to ATP: usable cellular energyTransforming energy

light food

ATP

ATP: Energy Currency for the cell Phosphate bonds are highly unstable.

H2O Pi

G = -7.3 kcal/mol

ATP powers many reactions in cells

ATP powers many reactions in cells

Active transport Specific transport protein required Energy required! Any kind of molecules Either direction

Can move against gradient Can transport all molecules

No equilibrium

Simple active transport Energy from ATP

Simple active transport Energy from ATP Directional transport One kind of molecule

Simple active transport PMCA transporter removes Ca2+ from cytoplasm

Very low [Ca2+] required for signaling

Ca2+

ATP

ADP

How do we get ATP from Glucose? Transfer energy stored in glucose to a storage molecule

ATP NADH

Glycolysis- Oxidizing glucose to pyruvate Citric Acid Cycle – Oxidizing pyruvate to CO2 Election Transport – Collecting electrons from NADH and

transferring this energy towards making ATP.

H-C-OH units Often used for energy by cells Glucose is a simple 6C sugar

Carbohydrates

Polymer: polysaccharides (complex carbohydrates) starch cellulose glycogen chitin peptidoglycan

Carbohydrates

Gain of electrons Increased number of bonds to O

O pulls e– from C

Oxidation

H – C – H

H

––

H

mostreduced

H – C – H

OH–

–

H

H – C – H

O

– –

H – C – OH

O

– –

O = C = O

mostoxidized

When one molecule is oxidized, another is reduced Electron carriers (“coenzymes”): NAD+, FAD

Oxidation reactions

H – C – H

OH–

–

H

H – C – H

O

– –oxidation

2 e–

reductionNAD+ NADH

oxidation

Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation

“Burning” sugars

freeenergy

(G)

reaction progress →

glucose

CO2

Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation

“Burning” sugars

O = C = O

Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation

“Burning” sugars

freeenergy

(G)

reaction progress →

glucose

CO2

Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation

“Burning” sugars

freeenergy

(G)

reaction progress →

glucose

CO2

Biochemical pathway Enzymes catalyze steps Energy captured in ATP

“Burning” sugars

freeenergy

(G)

reaction progress →

glucose

CO2

higherenergy

lowerenergy

Oxidized molecules have less chemical energy Energetic electrons transferred to carriers

“Burning” sugars

freeenergy

(G)

reaction progress →

glucose

CO2

H – C – H

OH

––

H

H – C – H

O

– –oxidation

2 e–

reductionNAD+ NADH

Complete oxidation of glucose

4 stages: Glycolysis Citric acid cycle Electron transport Chemiosmosis

Aerobic cell respiration

6 CO2

oxidationglucose

Partial oxidation of glucose in cytosol1. Glycolysis

2 pyruvateoxidationglucose

2 ATP, 2 NADHYum!gluT

First step: phosphorylation catalyzed by hexokinase Energy invested Allows facilitated transport

1. Glycolysis

glucose 6-phosphatehexokinaseglucose

ADPATP

P

hexokinase

Another phosphorylation step 6C molecule split into two 3C molecules

1. Glycolysis

glucose6-phosphate

glucose

ADPATP

P

ADPATP

PP

P

P

PFK

hexokinase

Oxidation Energy stored as high-energy e– on NADH

1. Glycolysis

glucose6-phosphate

glucose

ADPATP

P

ADPATP

PP

P

P

NADHNAD+

NADHNAD+

P

P

P

P

PFK

ATP

hexokinase

2 ATP synthesis steps Net gain of 2 ATP per glucose 6C glucose → 2 3C pyruvates

1. Glycolysis

glucose6-phosphate

glucose

ADPATP

P

ADPATP

PP

P

P

NADHNAD+

NADHNAD+

P

P

P

P

ATPADP

ATPADP

ADP

ATPADP

P

P

pyruvatePFK

AKA tricarboxylic acid cycle (TCA), AKA Krebs cycle Occurs in matrix of mitochondria (or cytosol in prokaryotes)

2. Citric Acid Cycle (CAC)

“Transition step” Transport into matrix Connects glycolysis to CAC

2. Citric Acid Cycle (CAC)

cytosol

i.m.o.m.

matrix

acetylCoA

pyruvate

CO2

Coenzyme A

NADH

NAD+

“Transition step” Large protein complex spans o.m. and i.m. Transporter and enzyme Oxidation of one carbon to CO2

Attachment of coenzyme A

2. Citric Acid Cycle (CAC)

cytosol

i.m.o.m.

matrix

acetylCoA

pyruvate

CO2

Coenzyme A

NADH

NAD+

2C acetyl CoA + 4C = 6C citric acid2. Citric Acid Cycle (CAC)

acetylCoA CoA

citric acid

2 oxidation reactions complete the oxidation of glucose2. Citric Acid Cycle (CAC)

acetylCoA

CO2

CoA

NADH

NAD+

citric acid

NADH

NAD+

CO2

One GTP synthesized and converted to ATP2. Citric Acid Cycle (CAC)

acetylCoA

CO2

CoA

NADH

NAD+

citric acid

NADH

NAD+

CO2

ATP

GDP

GTP ADP

Two more oxidation steps regenerate original 4C molecule2. Citric Acid Cycle (CAC)

acetylCoA

CO2

CoA

NADH

NAD+

citric acid

NADH

NAD+

CO2

ATP

GDP

GTP ADP

FADH2

FAD

NADHNAD+

Where’s the carbon from glucose?2. Citric Acid Cycle (CAC)

Where’s the carbon from glucose? 6 CO2

Where’s the energy from glucose?

2. Citric Acid Cycle (CAC)

Where’s the carbon from glucose? 6 CO2

Where’s the energy from glucose? 4 net ATP (2 from glycolysis, 2 for each pyruvate in CAC)

2. Citric Acid Cycle (CAC)

Where’s the carbon from glucose? 6 CO2

Where’s the energy from glucose? 4 net ATP (2 from glycolysis, 2 for each pyruvate in CAC) 10 NADH (2 glycolysis, 2 transition, 6 CAC)

2. Citric Acid Cycle (CAC)

Where’s the carbon from glucose? 6 CO2

Where’s the energy from glucose? 4 net ATP (2 from glycolysis, 2 for each pyruvate in CAC) 10 NADH (2 glycolysis, 2 transition, 6 CAC) 2 FADH2 (CAC)

2. Citric Acid Cycle (CAC)