unit 9

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Molecules of Life

Molecules of life are synthesized by living cellsCarbohydratesLipids Proteins Nucleic acids

Organic Compounds

Consist primarily of carbon and hydrogen atomsCarbon atoms bond covalently with up to four

other atoms, often in long chains or rings

Functional groups attach to a carbon backbone Influence organic compound’s properties

Building Organic Compounds

Cells form complex organic moleculesSimple sugars → carbohydratesFatty acids → lipidsAmino acids → proteinsNucleotides → nucleic acids

Dehydration synthesis combines monomers to form polymers

Carbohydrates – The Most Abundant Ones Three main types of carbohydrates

Monosaccharides (simple sugars)Oligosaccharides (short chains)Polysaccharides (complex carbohydrates)

Carbohydrate functionsInstant energy sources Transportable or storable forms of energyStructural materials

Oligosaccharides: Sucrose

Complex Carbohydrates: Starch, Cellulose, and Glycogen

Fats

Lipids with one, two, or three fatty acid tailsSaturated

Triglycerides (neutral fats )Three fatty acid tailsMost abundant animal fat (body fat)Major energy reserves

Greasy, Oily – Must Be Lipids

Lipids Fats, phospholipids, waxes, and sterolsDon’t dissolve in waterDissolve in nonpolar substances (other

lipids)

Lipid functionsMajor sources of energyStructural materialsUsed in cell membranes

Triglyceride Formation

Phospholipids Main component of

cell membranes Hydrophilic head,

hydrophobic tails

Waxes

Firm, pliable, water repelling, lubricating

Steroids: Cholesterol

Membrane components; precursors of other molecules (steroid hormones)

Protein Structure

Built from 20 kinds of amino acids

Four Levels of Protein Structure

1. Primary structure Amino acids joined by peptide bonds form a

linear polypeptide chain

2. Secondary structurePolypeptide chains form sheets and coils

3. Tertiary structureSheets and coils pack into functional domains

Four Levels of Protein Structure

4. Quaternary structureMany proteins (e.g. enzymes) consist of two

or more chains

Nucleotides, DNA, and RNAs

Nucleotide structure, 3 parts:SugarPhosphate groupNitrogen-containing base

Nucleotide Functions: Reproduction, Metabolism, and Survival

DNA and RNAs are nucleic acids, each composed of four kinds of nucleotide subunits

ATP energizes many kinds of molecules by phosphate-group transfers

Nucleotides of DNA

DNA, RNAs, and Protein Synthesis

DNA (double-stranded)Encodes information about the primary

structure of all cell proteins in its nucleotide sequence

RNA molecules (usually single stranded)Different kinds interact with DNA and one

another during protein synthesis

covalentbonding incarbonbackbone

hydrogen bondingbetween bases

Metabolism

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Metabolism• Metabolism – refers to all chemical reaction

occurring in body– Catabolism – break down complex molecules

• Exergonic – produce more energy than they consume

– Anabolism – combine simple molecules into complex ones• Endergonic – consume more energy than they

produce• Adenosine triphosphate (ATP)

– “energy currency”– ADP + P + energy ↔ ATP

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Energy transfer

• Oxidation-reduction or redox reactions– Oxidation – removal of electrons

• Decrease in potential energy• Dehydrogenation – removal of hydrogens• Liberated hydrogen transferred by coenzymes

– Nicotinamide adenine dinucleotide (NAD)– Flavin adenine dinucleotide (FAD)

• Glucose is oxidized

– Reduction – addition of electrons• Increase in potential energy

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3 Mechanisms of ATP generation

1. Substrate-level phosphorylation

○ Transferring high-energy phosphate group from an intermediate directly to ADP

1. Oxidative phosphorylation

○ Remove electrons and pass them through electron transport chain to oxygen

1. Photophosphorylation

○ Only in chlorophyll-containing plant cells

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Carbohydrate metabolism Fate of glucose depends on needs of

body cellsATP production or synthesis of amino acids,

glycogen, or triglycerides GluT transporters bring glucose into the

cell via facilitate diffusionInsulin causes insertion of more of these

transporters, increasing rate of entry into cells

Glucose trapped in cells after being phosphorylated

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Glucose catabolism / cellular respiration

1. Glycolysis

○ Anaerobic respiration – does not require oxygen

1. Formation of acetyl coenzyme A

2. Krebs cycle reactions

3. Electron transport chain reactions

○ Aerobic respiration – requires oxygen

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1NADH + 2 H+

GLYCOLYSIS2

2

2 Pyruvic acid

1 Glucose

ATP1

NADH + 2 H+

GLYCOLYSIS

+ 2 H+NADH

CO2FORMATIONOF ACETYLCOENZYME A

2

2

2

2

2 Acetylcoenzyme A

2 Pyruvic acid

1 Glucose

ATP

2

1NADH + 2 H+

GLYCOLYSIS

+ 2 H+NADH


KREBSCYCLE

+ 6 H+

CO2

FADH2

NADH

2

4

6

2

2

2

2

2

2 Acetylcoenzyme A

2 Pyruvic acid

1 Glucose

ATP

ATP

2

3

1NADH + 2 H+

GLYCOLYSIS

+ 2 H+NADH


KREBSCYCLE

+ 6 H+

CO2

FADH2

NADH

2

4

6

2

ELECTRONTRANSPORTCHAIN

e–

e–

e–

32 or 34

O26

6

2

2

2

2

H2O

Electrons

2 Acetylcoenzyme A

2 Pyruvic acid

1 Glucose

ATP

ATP ATP

2

3

4

Overview of cellular respiration

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Glycolysis

1. Glycolysis– Splits 6-carbon glucose into 2 3-carbon

molecules of pyruvic acid– Consumes 2 ATP but generates 4– 10 reactions– Fate of pyruvic acid depends on oxygen

availability• If oxygen is scarce (anaerobic), reduced to

lactic acid– Hepatocytes can convert it back to pyruvic acid

• If oxygen is plentiful (aerobic), converted to acetyl coenzyme A

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Cellular respiration begins with glycolysis

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ADP

O

Glucose (1 molecule)

CH2OH

OH

OH

OH4 1

3 2

5

6

ATP

H H

H

HHO

1

H

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

OH2CP

ATP

H

HO

H

H

HH

H

H

H

HO

1

2

H

H

Phosphofructokinase

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH

Fructose 6-phosphate

O

OH

H

OH2C6

5

4 3

2

1

ADP

P

OH2CP

ATP

ATP

OH

H

HO

H

H

HH

H H

H

H

HO

H

HO

1

2

3

H

H

Phosphofructokinase

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O

Fructose 1, 6-bisphosphate

O

OH

H

OH2C

ADP

PP

P

OH2CP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

H

H

Phosphofructokinase

Dihydroxyacetonephosphate

CH2OH

CH2O

C O

Glyceraldehyde3-phosphate

HCOH

CH2O

OHC

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O


O

OH

H

OH2C

ADP

PP

P

P

P

OH2CP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

5

H

H

+ 2H+NADH

HCOH

C

CH2O

O

O 1, 3-Bisphosphoglyceric acid(2 molecules)

2

P

P

Phosphofructokinase


CH2OH

CH2O

C O


HCOH

CH2O

OHC

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O


O

OH

H

OH2C

ADP

PP

P

P

P

OH2CP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

5

6

H

H

2 NAD+ + 2 P

+ 2H+NADH

HCOH

C

CH2O

O

COOH

O

2

2 ADP

HCOH

CH2O

1, 3-Bisphosphoglyceric acid(2 molecules)

2

3-Phosphoglyceric acid(2 molecules)

P

P

P

Phosphofructokinase


CH2OH

CH2O

C O


HCOH

CH2O

OHC

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O


O

OH

H

OH2C

ADP

PP

P

P

P

OH2CP

ATP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

5

6

7H

H

2 NAD+ + 2 P

+ 2H+NADH

HCOH

C

CH2O

O

COOH

O

2

2 ADP

HCOH

CH2O


2


COOH

CH2OH

HCO 2-Phosphoglyceric acid(2 molecules)

P

P

P

P

Phosphofructokinase


CH2OH

CH2O

C O


HCOH

CH2O

OHC

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O


O

OH

H

OH2C

ADP

PP

P

P

P

OH2CP

ATP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

5

6

7

8

H

H

2 NAD+ + 2 P

+ 2H+NADH

HCOH

C

CH2O

O

COOH

O

2

2 ADP

HCOH

CH2O


2


COOH

CH2OH


COOH

CH2

C O Phosphoenolpyruvic acid(2 molecules)

P

P

P

P

P

Phosphofructokinase


CH2OH

CH2O

C O


HCOH

CH2O

OHC

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O


O

OH

H

OH2C

ADP

PP

P

P

P

OH2CP

ATP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

5

6

7

8

9

H

H

2 NAD+ + 2 P

+ 2H+NADH

2 NAD+ + 2

HCOH

C

CH2O

O

COOH

O

2

2 ADP

P

HCOH

CH2O


2


COOH

CH2OH


Pyruvic acid(2 molecules)

COOH

CH2

2

2 ADP

C O Phosphoenolpyruvic acid(2 molecules)

COOH

CH3

C O

P

P

P

P

P

Phosphofructokinase


CH2OH

CH2O

C O


HCOH

CH2O

OHC

ADP

O


CH2OH

OH

OH

OH4 1

3 2

5

6

Glucose 6-phosphate

O

OH

OH

OH

CH2OH


O

OH

H

OH2C6

5

4 3

2

1

CH2O


O

OH

H

OH2C

ADP

PP

P

P

P

OH2CP

ATP

ATP

ATP

ATP

OH

H

HO

H

H

HH

H

H

H

H

H

H

HO

HO

H

HO

OH

1

2

3

4

5

6

7

8

9

10

H

H

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Formation of Acetyl coenzyme A

2. Formation of Acetyl coenzyme A

Each pyruvic acid converted to 2-carbon acetyl group

○ Remove one molecule of CO2 as a waste product

Each pyruvic acid also loses 2 hydrogen atoms

○ NAD+ reduced to NADH + H+

Acetyl group attached to coenzyme A to form acetyl coenzyme A (acetyl CoA)

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The Krebs cycle

3. The Krebs cycle Also known as citric acid cycle Occurs in matrix of mitochondria Series of redox reactions

2 decarboxylation reactions release CO2

Reduced coenzymes (NADH and FADH2) are the most important outcome

One molecule of ATP generated by substrate-level phosphorylation

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1

C

CH2

COOH

O

Oxaloacetic acid

COOHCitric acid

H2C COOH

COOHHOC

H2C COOH

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O

To electrontransport chain

H2O

CO2

NAD+

KREBSCYCLE

NADH

CoA

CoA

1

C

CH2

COOH

O

Oxaloacetic acid

COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


H2O

CO2

NAD+

KREBSCYCLE

NADH

CoA

CoA

2

1


CO2

+ H+

C

CH2

COOH

O

Oxaloacetic acid

COOH

Alpha-ketoglutaric acid

H2C COOH

HCH

C COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

NAD+

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


H2O

CO2

NAD+

KREBSCYCLE

NADH

NADH

CoA

CoA

2

3

O

1


CO2

+ H+NADH

CO2

+ H+

C

CH2

COOH

O

Oxaloacetic acid

COOH

Succinyl CoA

H2C COOH

CH2

C S CoA Alpha-ketoglutaric acid

H2C COOH

HCH

C COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

NAD+

NAD+

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


H2O

CO2

NAD+

KREBSCYCLE

NADH

NADH

O

CoA

O

CoA

2

3

4

1


CO2

+ H+NADH

CO2

+ H+

C

CH2

COOH

O

Oxaloacetic acid

COOH

H2C COOH

H2C COOHSuccinic acid

Succinyl CoA

H2C COOH

CH2


H2C COOH

HCH

C COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

NAD+

NAD+

GDP

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


ADP

H2O

CO2

NAD+

KREBSCYCLE

NADH

NADH

ATP

GTP

O

CoA

CoA

O

CoA

2

3

4

5

1


CO2

+ H+NADH

CO2

+ H+

To electrontransportchain

C

CH2

COOH

O

Oxaloacetic acid

COOH

H2C COOH


Succinyl CoA

H2C COOH

CH2


H2C COOH

HCH

C COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

Fumaric acid

NAD+

NAD+

GDP

FAD

HC

CH

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


ADP

FADH2

COOH

COOH

H2O

CO2

NAD+

KREBSCYCLE

NADH

NADH

ATP

GTP

CoA

CoA

O

CoA

2

3

4

5

6

O

1


CO2

+ H+NADH

CO2

+ H+


C

CH2

COOH

O

Oxaloacetic acid

COOH

HCOH

CH2

COOH

COOH

H2C COOH


Malic acid

Succinyl CoA

H2C COOH

CH2


H2C COOH

HCH

C COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

Fumaric acid

NAD+

NAD+

GDP

FAD

HC

CH

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


ADP

FADH2

COOH

COOH

H2O

H2O

CO2

NAD+

KREBSCYCLE

NADH

NADH

ATP

GTP

CoA

CoA

O

CoA

2

3

4

5

6

7

O

1


CO2

+ H+NADH

CO2

+ H+


C

CH2

COOH

O

Oxaloacetic acid

COOH

+ H+NADH

HCOH

CH2

COOH

COOH

H2C COOH


Malic acid

Succinyl CoA

H2C COOH

CH2


H2C COOH

HCH

C COOH

Isocitric acid

H2C COOH

HOC COOH

HC COOH

H

Citric acid

H2C COOH

COOHHOC

H2C COOH

Fumaric acid

NAD+

NAD+

GDP

FAD

NAD+

HC

CH

+ H+Pyruvic

acidAcetyl

coenzyme A

C

CH3

O

CH3

C

COOH

O


ADP

FADH2

COOH

COOH

H2O

H2O

CO2

NAD+

KREBSCYCLE

NADH

NADH

ATP

GTP

CoA

CoA

O

CoA

2

3

4

5

6

7

8

O

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Electron transport chain

4. Electron transport chain Series of electron carriers in inner

mitochondrial membrane reduced and oxidized

As electrons pass through chain, exergonic reactions release energy used to form ATP

○ Chemiosmosis

Final electron acceptor is oxygen to form water

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ChemiosmosisCarriers act as proton pumps to expel H+ from

mitochondrial matrixCreates H+ electrochemical gradient – concentration

gradient and electrical gradientGradient has potential energy – proton motive forceAs H+ flows back into matrix through membrane,

generates ATP using ATP synthesis

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Energy fromNADH + H+

H+

Low H+ concentration inmatrix of mitochondrion

Innermitochondrialmembrane

Matrix

High H+ concentrationbetween inner andouter mitochondrialmembranes

Outer membrane

Inner membrane

H+

channel

Electrontransport

chain(includes

proton pumps)

1 Energy fromNADH + H+

H+

H+

Low H+ concentration inmatrix of mitochondrion


Matrix


Outer membrane

Inner membrane

H+

channel

Electrontransport

chain(includes

proton pumps)

1

2

Energy fromNADH + H+

H+

H+

ADP +

ATP synthaseLow H+ concentration inmatrix of mitochondrion


Matrix


Outer membrane

Inner membrane

H+

channel

Electrontransport

chain(includes

proton pumps)

P

ATP

1

2

3

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The actions of the three proton pumps and ATP synthase in the inner membrane of mitochondria

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Space between outerand inner mitochondrialmembranes

Innermito-chondrialmembrane

Mitochondrialmatrix

H+ channel

NADH dehydrogenasecomplex: FMN andfive Fe-S centers

NAD

e–

H++ + + + + + +

– – – – – – –

Q

NADH+ H+

1



Mitochondrialmatrix

H+ channel


Cytochrome b-c1

complex: cyt b, cyt c1, and an Fe-S center

NAD

e–

e–

e–

H++ + + + + + +

– – – – – – –

Q

Cyt c

NADH+ H+ H+

1 2



Mitochondrialmatrix

H+ channel


Cytochrome b-c1

complex: cyt b, cyt c1, and an Fe-S center

Cytochrome oxidasecomplex: cyt a, cyt a3,and two Cu

NAD1 1/2 O2

e–

e–

e–

e–

e–

H+ H+H+

+ + + + + + +

– – – – – – –

H2O

Q

Cyt c

NADH+ H+ H+

3

ADP +

ATP synthase

P

ATP

1 2 3

3

Summary of cellular respiration

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Glucose anabolism

Glucose storage: glycogenesis○ Polysaccharide that is the only stored

carbohydrate in humans○ Insulin stimulates hepatocytes and skeletal

muscle cells to synthesize glycogen

Glucose release: glycogenolysis○ Glycogen stored in hepatocytes broken down

into glucose and release into blood

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Glycogenesis and glycogenolysis

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Formation of glucose from proteins and fats: gluconeogenesis

○ Glycerol part of triglycerides, lactic acid, and certain amino acids can be converted by the liver into glucose

○ Glucose formed from noncarbohydrate sources

○ Stimulated by cortisol and glucagon

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Lipid metabolism Transport by

lipoproteins Most lipids nonpolar

and hydrophobic Made more water-

soluble by combining them with proteins to form lipoproteins

Proteins in outer shell called apoproteins (apo)○ Each has specific

functions○ All essentially are

transport vehicles

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Apoproteins Apoproteins categorized and named according to density

(ratio of lipids to proteins)◦ Chylomicrons

Form in small intestine mucosal epithelial cells Transport dietary lipids to adipose tissue◦ Very low-density lipoproteins (VLDLs)

Form in hepatocytes Transport endogenous lipids to adipocytes◦ Low-density lipoproteins (LDLs) – “bad” cholesterol

Carry 75% of total cholesterol in blood Deliver to body cells for repair and synthesis Can deposit cholesterol in fatty plaques ◦ High-density lipoproteins (HDLs) – “good” cholesterol

Remove excess cholesterol from body cells and blood Deliver to liver for elimination

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Lipid Metabolism 2 sources of cholesterol in the body

Present in foodsSynthesized by hepatocytes

As total blood cholesterol increases, risk of coronary artery disease begins to riseTreated with exercise, diet, and drugs

Lipids can be oxidized to provide ATPStored in adipose tissue if not needed for ATP

Major function of adipose tissue to remove triglycerides from chylomicrons and VLDLs and store it until needed98% of all body energy reserves

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Lipid Metabolism• Lipid catabolism: lipolysis

– Triglycerides split into glycerol and fatty acids

– Must be done for muscle, liver, and adipose tissue to oxidize fatty acids

– Enhanced by epinephrine and norepinephrine

• Lipid anabolism: lipogenesis– Liver cells and adipose cells synthesize

lipids from glucose or amino acids– Occurs when more calories are consumed

than needed for ATP production

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Pathways of lipid metabolism

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Protein metabolism• Amino acids are either oxidized to produce

ATP or used to synthesize new proteins• Excess dietary amino acids are not excreted

but converted into glucose (gluconeogenesis) or triglycerides (lipogenesis)

• Protein catabolism– Proteins from worn out cells broken down into

amino acids– Before entering Krebs cycle amino group must be

removed – deamination • Produces ammonia, liver cells convert to urea,

excreted in urine

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Protein anabolism

Carried out in ribosomes of almost every cell in the body10 essential amino acids in the human

○ Must be present in the diet because they cannot be synthesized

○ Complete protein – contains sufficient amounts of all essential amino acids – beef, fish, poultry, eggs

○ Incomplete protein – does not – leafy green vegetables, legumes, grains

10 other nonessential amino acids can be synthesized by body cells using transamination

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Various points at which amino acids enter the Krebs cycle for oxidation

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Key molecules at metabolic crossroads• 3 molecules play pivotal roles in

metabolism• Stand at metabolic crossroads –

reactions that occur or not depend on nutritional or activity status of individual

1. Glucose 6-phosphate– Made shortly after glucose enters body cell– 4 fates – synthesis of glycogen, release of

glucose into blood stream, synthesis of nucleic acids, glycolysis

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Key molecules at metabolic crossroads2. Pyruvic acid

If there is enough oxygen, aerobic cellular respiration occurs

If there is not enough oxygen, anaerobic reactions can produce lactic acid, produce alanine or gluconeogenesis

2. Acetyl Coenzyme A When ATP is low and oxygen plentiful, most pyruvic acid

goes to ATP production via Acetyl CoA Acetyl CoA os the entry into the Krebs cycle Can also be used for synthesis of certain lipids

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Metabolic adaptations• During the absorptive state ingested

nutrients are entering the blood stream– Glucose readily available for ATP production

• During postabsorptive state absorption of nutrients from GI tract complete– Energy needs must be met by fuels in the

body– Nervous system and red blood cells depend

on glucose so maintaining steady blood glucose critical

– Effects of insulin dominate

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Metabolism during absorptive state

Soon after a meal nutrients enter blood○ Glucose, amino acids, and triglycerides in

chylomicrons

2 metabolic hallmarks○ Oxidation of glucose for ATP production in all body

cells○ Storage of excess fuel molecules in hepatocytes,

adipocytes, and skeletal muscle cells

Pancreatic beta cells release insulin○ Promotes entry of glucose and amino acids into cells

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Principal metabolic pathways during the absorptive state

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AMINO ACIDS GLUCOSE TRIGLYCERIDES(in chylomicrons)

Blood

GLUCOSE

GASTROINTESTINALTRACT

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

1


Blood

GLUCOSE


HEPATOCYTES IN LIVER

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Fatty acids

Triglycerides

Glyceraldehyde3-phosphate Glycogen

Glucose

+ H2O +CO2 ATP

1

2


Blood

GLUCOSE



+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Triglycerides

ADIPOSE TISSUE

VLDLs

Triglycerides

Fatty acids

Triglycerides


Glucose

+ H2O +CO2 ATP

1

2

3


Blood

GLUCOSE


GLUCOSE


SKELETALMUSCLE

Storage

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Triglycerides

ADIPOSE TISSUE

VLDLs

Fattyacids

Triglycerides


Glucose

Fatty acids

Triglycerides


Glucose

GlycogenGlycogen

+ H2O +CO2 ATP

1

2

3

4

4


Blood

GLUCOSE


GLUCOSE


SKELETALMUSCLE

Storage

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Triglycerides

ADIPOSE TISSUE

VLDLs

Triglycerides

Fattyacids

Triglycerides


Glucose

Fatty acids

Triglycerides


Glucose

GlycogenGlycogen

+ H2O +CO2 ATP

1

2

3

4 5

4


Blood

GLUCOSE


GLUCOSE


SKELETALMUSCLE

Storage

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Triglycerides

ADIPOSE TISSUE

VLDLs

Triglycerides

Fattyacids

Triglycerides


Glucose

Keto acids

Fatty acids

Triglycerides


Glucose

GlycogenGlycogen

+ H2O +CO2 ATP

1

2

3

4 5

6

4


Blood

GLUCOSE


GLUCOSE


SKELETALMUSCLE

Storage

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Triglycerides

ADIPOSE TISSUE

VLDLs

Triglycerides

Fattyacids

Triglycerides


Glucose

Keto acids

Fatty acidsProteins

Triglycerides


Glucose

GlycogenGlycogen

+ H2O +CO2 ATP

1

2

3

4 5

67

4


Blood

GLUCOSE


GLUCOSE


SKELETALMUSCLE

Storage

+ H2O +CO2

MOST TISSUES

Oxidation

ATP

Triglycerides

ADIPOSE TISSUE

VLDLs

Triglycerides

Fattyacids

Triglycerides


Glucose

Keto acids

Fatty acidsProteins

Triglycerides


Glucose

GlycogenGlycogen

ProteinsProteins

+ H2O +CO2 ATP

1

2

3

4 5

67

8

4

life saving son

Metabolism during postabsorptive stateAbout 4 hours after the last meal absorption in

small intestine nearly completeBlood glucose levels start to fallMain metabolic challenge to maintain normal

blood glucose levelsGlucose production

○ Breakdown of liver glycogen, lipolysis, gluconeogenesis using lactic acid and/or amino acids

Glucose conservation○ Oxidation of fatty acids, lactic acid, amino acids,

ketone bodies and breakdown of muscle glycogen

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Principal metabolic pathways during the postabsorptive state

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1

Liver glycogen

Glucose

LIVER

Blood

HEARTADIPOSE TISSUESKELETAL MUSCLE TISSUE

OTHER TISSUES

1

Liver glycogen

Glucose

LIVER

Glycerol

Blood

HEART

Fatty acidsGlycerol

TriglyceridesADIPOSE TISSUE

SKELETAL MUSCLE TISSUE

OTHER TISSUES

2

Fatty acids

1

Liver glycogen

Glucose

LIVER

Lactic acid

Glycerol

Blood

HEART

Fatty acidsGlycerol



OTHER TISSUES

3

2

Fatty acids

1

Liver glycogen

Keto acids

Glucose

Amino acids

LIVER

Lactic acid

Glycerol

Blood

HEART

Muscle proteins

Fatty acidsGlycerol


Fasting orstarvation


OTHER TISSUES

ProteinsAmino acids

Amino acids

4

4

3

4

2

Fatty acids

1

Liver glycogen

Keto acids

Glucose

Amino acids

LIVER

Lactic acid

Glycerol

Blood

HEART

Fatty acids

Muscle proteins

Fatty acidsGlycerol




OTHER TISSUES

Fatty acids

ProteinsAmino acids

Amino acidsFatty acids

ATP

ATP

ATP

4

5

5

4

3

5

4

2

Fatty acids

1

Liver glycogen

Keto acids

Glucose

Amino acids

LIVER

Lactic acid

Glycerol

Blood

HEART

Fatty acids

Muscle proteins

Fatty acidsGlycerol




OTHER TISSUES

Fatty acids

ProteinsAmino acids


Lactic acid

ATP

ATP

ATP

ATP

4

5

5

6

4

3

5

4

2

Fatty acids

1

Liver glycogen

Keto acids

Glucose

Amino acids

LIVER

Lactic acid

Glycerol

Blood

HEART

Fatty acids

Muscle proteins

Fatty acidsGlycerol




OTHER TISSUES

Fatty acids

ProteinsAmino acids


Lactic acid

ATP

ATPATP

ATP

ATP

4

5

5

67

4

3

5

4

2

Fatty acids

1

Liver glycogen

Keto acids

Glucose

Amino acids

LIVER

Fatty acids

Lactic acid

Ketone bodies

Glycerol

Blood

NERVOUSTISSUE Ketone

bodiesGlucose

Starvation

HEART

Fatty acids

Muscle proteins

Fatty acidsGlycerol




Ketone bodies

OTHER TISSUES

Fatty acids

ProteinsAmino acids


Ketone bodies

Lactic acid

ATP

ATP

ATP

ATP

ATP

ATP

ATP

ATP

ATP ATP

4

5

8

5

6

88

7

4

3

5

4

2

8

1

Liver glycogen

Keto acids

Glucose

Amino acids

LIVER

Fatty acids

Lactic acid

Ketone bodies

Glycerol

Blood

NERVOUSTISSUE Ketone

bodiesGlucose

Starvation

HEART

Fatty acids

Muscle proteins

Fatty acidsGlycerol




Ketone bodies

OTHER TISSUES

Fatty acids

ProteinsAmino acids

Glucose6-phosphate

Pyruvic acid

Lacticacid

Muscle glycogen

(aerobic) (anaerobic)


Ketone bodies

Lactic acid

ATP

O2

ATP

ATP

ATP

ATP

ATP

ATP

ATP

ATP

ATP

ATP ATP

+ O2–

4

5

8

5

6

88

7

4

3

9

5

4

2

8

life saving son

Hormones and autonomic nervous system regulate metabolism during postabsorptive state

As blood glucose decline, insulin secretion falls○ Glucagon – increases release of glucose into blood

via gluconeogenesis and glycogenolysis

Sympathetic nerve endings of ANS release norepinephrine and adrenal medulla releases epinephrine and norepinephrine○ Stimulate lipolysis, glycogen breakdown

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Heat and energy balance

Heat – form of energy that can be measured as temperature and can be expressed in caloriescalorie (cal) – amount of heat required to raise 1

gram of water 1°CKilocalorie (kcal) or Calorie (Cal) is 1000 calories

Metabolic rate – overall rate at which metabolic reactions use energySome energy used to make ATP, some lost as heatBasal metabolic rate (BMR) – measurement with

body in quiet, resting, fasting condition

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Body temperature homeostasis

Despite wide fluctuations in environmental temperatures, homeostatic mechanisms maintain normal range for internal body temperature

Core temperature (37°C or 98.6°F) versus shell temperature (1-6°C lower)

Heat produced by exercise, some hormones, sympathetic nervous system, fever, ingestion of food, younger age, etc.

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Heat and engery balance

• Heat can be lost through– Conduction to solid materials in contact with

body– Convection – transfer of heat by movement of a

gas or liquid– Radiation – transfer of heat in form of infrared

rays– Evaporation exhaled air and skin surface

(insensible water loss)• Hypothalamic thermostat in preoptic area

– Heat-losing center and heat-promoting center

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life saving son

unit 9

Healthcare

kinds of molecules

simple molecules

cell proteins

primary structure amino

complex onesendergonic

complex moleculesexergonic

rnasnucleotide structure

single strandeddifferent