Carbohydrates

a) Solar energy Carbohydrates Other organic compounds

b) Definition : Carbohydrates contain carbon, hydrogen, and oxygen which can directly, or indirectly after hydrolysis, reduce alkali solutions of heavy metal salts. They are generally known as POLYHYDROXYALDEHYDES or KETONES and can yield aldehydes or ketones upon hydrolysis.

Carbohydrate = “hydrated carbons”. The general formula is : Cm(H2O)n

c) Types :1) MONOSACCHARIDES 2C 9C : the simplest of carbohydrates in that they cannot yield smaller molecules upon hydrolysis

2) OLIGOSACCHARIDES 2 10 monosaccharides units : joined by GLYCOSIDIC LINK : oligosaccharides, upon hydrolysis, will yield constituent monosaccharides

3) POLYSACCHARIDES > 10 monosaccharide units joined by glycosidic links : oligosaccharides, upon hydrolysis, will yield constituent monosaccharides

4) HOMOPOLYSACCHARIDES contain the same monosaccharide units

5) HETEROPOLYSACCHARIDES contain different monosaccharide units

photosynthesis

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Carbohydrates

d) BIOCHEMICAL IMPORTANCE

1) Energy provision and storage2) Structure and protection3) Conversion to other compounds eg. Carbohydrates Fat4) Internal units of other compounds

eg. Ribose in RNA NAD etc.

Monosaccharides

ALDOSES : Contain Aldehyde groupings ( ose = sugar ) KETOSES : Contain Ketone groupings

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ALDOSESTRIOSES

: D-glyceraldehyde (OH on right hand side): D- SERIES SUGARS: predominent sugars in nature are in the D- series: L- series sugars can not be used

simplest

KETOSES

A sugar with 3 carbon atoms is known as TRIOSE (aldehyde, ketone)

TETROSES

Aldose form

D- ERYTHROSEAldose sugarin D series

Ketose form

D- ERYTHROLOSEKetone sugar in D-series

H

OC OHH

CH2OH

CO

CH2OH

CH2OH

C

Carbohydrates

(1)(2)*

* n - 1

C OHH

CH2OH

OHH

C O

H

C*

*

* chiral center

O

CH2OH

CCH2OH

OHHC

*

* only one chiral center

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Carbohydrates

PENTOSES (5 C)ALDOSES 4 D-SERIES MEMBERSKETOSES 2 D- SERIES MEMBERS

HEXOSES (6 C)ALDOSES 8 D- SERIES MEMBERSKETOSES 4 D-SERIES MEMBERS

RING STRUCTURES (cyclic form)

PYRANE PYRANOSE

HEMIACETAL

Hemiacetal is a condensation of aldehyde and hydroxy (-OH) groups.

C

C

OC

C

C C C

C

OC

COH

*

* chiral center

C

O

CC

C

C

OH

1

5

- carbon chain tends to bend back upon itself- =O and -OH brought together to favour HEMIACETAL FORMATION

H

OC

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HEMIACETAL FORMATION

PYRANOSE : contains 5 carbons and 1 oxygen. Aldose form : The oxygen is placed between the carbons at the position C1

and C5.

Ketose form : The oxygen is placed between the carbons at the position C2 and C6.

FURANOSE : contains 4 carbons and 1 oxygen.

Aldose form : The oxygen is placed between the carbons at the position C1 and C4.

Ketose form : The oxygen is placed between the carbons at the position C2 and C5.

C

O

CC

C

C

CH2OH

PYRANOSE

123

4

5 6

12

3

4 5

C

CH2OH

OC

C C

FURANOSE

12

3

45

12

3 4

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As a consequence of ring structure we have a chiral center.If OH is projecting downwards α anomerIf OH is projecting upwards β anomer

f) REACTIVITY

1) Potential reducing group

: an unreacted OH group at C1 of aldose and C2 of ketose : an unreacted OH group is a potential reducing group, forming a straight-chain molecule with an aldehyde grouping on the end

anomer anomer

aldehydegrouping

straightchainform

HEMIACETAL FORMATION

O

OH

O OH O

OH

OOH

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O

OH

O

H O OH

C C C

HEMIACETAL FORMATION

2) High capacity to rotate plane polarized light (POLARIMETER)

- Translated in to sugar units.

3) Separation by CHROMATOGRAPHY

- HPLC- Gas chromatography (use of derivatives)

4) High capacity to interact with water

- Hydrophilic

Naturally Occurring Monosaccharides

TRIOSES

D-GLYCERALDEHYDE-3-PHOSPHATEDIHYDROXYACETONE PHOSPHATE

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PENTOSES

-D-DEOXYRIBOFURANOSE ( DNA )

HOH2

HEXOSES

a)

HOH

O

CH2OH

OH OH OH

D- MANOSE

b)

D-GLUCOPYRANOSE is the most abundantmonosaccharide in nature. We can find the freeform in animal blood. It feeds the brain and is foundin plant sap. The combined form is: Oligosaccharides

: Polysaccharides.

D-MANOSE is a naturallyoccuring aldose.The combined form is: Polysaccharides: Mucopolysaccharides

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O

OH OH

OHCHOH2

-D-RIBOFURANOSE

( RNA, NAD, Co Acet )

O

OH H

OHC

HOH

O

CH2OH

OH OH

OH

D-GLUCOPYRANOSE(D-GLUCOSE)

Combined form in Oligosaccharides and Polysaccharides.

In free form it occurs as Pyranose, but incombined form it occurs as Furanose.In the -anomer, the OH hangs down(involved in cyclic form of sugar).

anomer

Ring structures have to involve aldehyde or ketone groupings.

Fructose : in free form is sweet: component of foetal animal blood: component of photosynthetic plant sap: present in seminal fluid (provides energy for sperm): basic building blocks of oligo and polysaccharides

HOH

O

CH2OH

OH

OH

OH

O

OH

OH

CH2OH

OH

CHOH2

D-GALACTOSE

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KETOHEXOSES (D-FRUCTOSE)

MONOSACCHARIDES DERIVATIVES

: modification of structure

1) AMINO SUGARS

HOH

O

CH2OH

OH OH

NH2

2-AMINO-D-GLUCOSE = D- GLUCOSAMINE

NH C

O

CH3

Frequently NH2 (basic)occurs as:

(N acetyl grouping). This removes the basicity of NH2 .

D- GALACTOSAMINED- MANNOSAMINE

: these amino sugars give us MUCOPOLYSACCHARIDES (components by definition): associated with structure and protection of cells: they are also occasionally acylated

(neutral)

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COH

COOH

COH

CH2OH

COOH

CH2OH

MONOSACCHARIDES DERIVATIVES

2) SUGAR ACIDS

D-GLUCURONIC ACIDD-GALACTURONIC ACIDD-MANNURONIC ACID

[o] [o]

readilyoxidized

readilyoxidized

HOH

O

COOH

OHSH

OH

COO-

URONIC ACIDFAMILY

ALDONIC ACIDFAMILY

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MONOSACCHARIDE FAMILY

C

C

O

H

CH2OH

H OH

C

C

O

H

CH2OH

OH H

C

C

OH

C

CH2OH

H OH

O

H

H

C

C

OH

C

CH2OH

H OH

OH

C

H

O

H

H

C

C

OH

C

CH2OH

H OH

OH

C

H

OH

C

H

O

H

H

C

C

OH

C

CH2OH

H OH

OH

C

H

H

C

H

O

OH

H

C

C

OH

C

CH2OH

H OH

H

C

H

OH

C

OH

O

H

H

C

C

OH

C

CH2OH

H OH

H

C

H

H

C

OH

O

OH

H

C

C

H

C

CH2OH

H OH

OH

C

OH

OH

C

H

O

H

H

C

C

OH

C

CH2OH

H OH

OH

C

OH

H

C

H

O

OH

H

C

C

H

C

CH2OH

H OH

H

C

OH

OH

C

OH

O

H

H

C

C

H

C

CH2OH

H OH

H

C

OH

H

C

OH

O

OH

H

C

C

OH

C

CH2OH

H OH

H

C

H

O

H

OH

C

C

H

C

CH2OH

H OH

OH

C

OH

O

H

H

C

C

H

C

CH2OH

H OH

H

C

OH

O

H

OH

C

C

H

C

CH2OH

H OH

O

H

OH

TRIOSES (3c)

Asymmetric C=1

21 = 2 isomers

TETROSES (4c)

Asymmetric C=2

22= 4 isomers

21 = 2D series isomers

PENTOSES (5c)

23= 8 isomers

22 = 4D series isomers

HEXOSES (6c)

24 = 16 isomers

23= 8D series isomers

ALDOSES

D-GLYCERALDEHYDE L-GLYCERALDEHYDE

D-ERYTHROSE D-THREOSE

D-RIBOSE D-ARABINOSE D-XYLOSE D-LYXOSE

D-ALLOSE D-ALTROSE D-GLUCOSE D-MANNOSE D-GULOSE D-IDOSE D-GALACTOSE D-TALOSE

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MONOSACCHARIDE FAMILY

C

CH2OH

OH

C O

CH2OH

H

C OH

C OH

C

H

O

CH2OH

H

CH2OH

C

CH2OH

OH

C OH

C

H

OH

C

H

O

H

CH2OH

KETOSES

C OH

C H

C

H

O

CH2OH

OH

CH2OH

C

CH2OH

OH

C OH

C

H

H

C

H

O

OH

CH2OH

C

CH2OH

OH

C H

C

H

OH

C

OH

O

H

CH2OH

C

CH2OH

OH

C H

C

H

H

C

OH

O

OH

CH2OH

CH2OH

C

CH2OH

O

DIHYDROXYACETONE

Asymmetric C=0

20 = 1 compound

Asymmetric C=1

21 = 2 isomers

20 =1D series COMPOUND

22= 4 isomers

21 = 2 D series isomers

23 = 8 isomers

22= 4 D series isomers

D-ERYTHRULOSE

D-RIBULOSE D-XYLULOSE

D-ALLULOSE D-FRUCTOSE D-SORBOSE D-TAGATOSE

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MONOSACCHARIDES

DetoxicationDetoxication makes sugar acids more water soluble so they can be excreted (eg. ASPIRIN derivative of D-glucuronic acid).In combined form, these turn up in various polysaccharides.Can vary the behaviour of carbohydrates by potential basic group (negative group)on uronic acid.

Monosaccharides : are joined via glycosidic link.

OLIGOSACCHARIDES

: and exist in equilibrium: if starting off with the form METHYL--D-GLUCOSIDE: there would be a potential for two entirely different compounds

O

CH2OH

OHOH

OH

OH

O

CH2OH

OHOH

OH

OCH3

+ HO H3C

H2O

a type of glycoside

ethanol

METHYL - D-GLUCOSIDE

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1)-GLUCOSIDE : is easily hydrolyzed: succeptible to attack by -GLUCOSIDASE enzyme

2)-GLUCOSIDE : is less easily hydrolyzed: also attacked by -GLUCOSIDASE enzyme

-GLYCOSIDIC LINKS: polysaccharides involved in energy production: is easily hydrolyzed and can be attacked by an enzyme

-GLYCOSIDIC LINKS: is extremly hard to hydrolyze and very stable: has biological importance in structure and protective compounds: OH group can be provided by another sugar (naturally occurring disaccharides)

OLIGOSACCHARIDES

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O

CH2OH

H

H

OH

H

OH

OH

HO

H

O

CH2OH

H

H

OH

H

OH

OH

HH

O

O

CH2OH

OHOH

OH

O

H2O

O

CH2OH

OH

OH

1 4

-GLYCOSIDIC LINK MALTOSE

FULL ACETAL (not hemi)

NATURALLY OCCURING DISACCHARIDES

1)

Maltose is the same as Methanol except that it uses OH on the second sugar group.As soon as this occurs the ring structure cannot be opened.

2)

Maltose: a naturally occuring disaccharide: a degradation product of starch: easily hydrolyzed

O

CH2OH

OHOH

OH

O HOH

O

CH2OH

OH

OH

potential reducinggroup (it can reactwith heavy metals)

- GLYCOSIDIC LINK CELLOBIOSE

Cellobiose: a degradation product of cellulose

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3)

Lactose is a milk sugar (5% composition of milk). It provides energy for infants.Lactose intolerance is the lack of enzyme that helps to digest lactose.

O

CH2OH

OH

OHO

OH

OH

OH

OHOH2C

*

-D- GLUCOSE

- D- FRUCTOSE

4)* : no unreacted OH grouping : locked tight shut : no potential reducing group : NON-REDUCING SUGAR : it does not have the capacity to reduce heavy metals or salts

Sucrose: sweetener: plant product: commercial - sugar cane

- sugar beet

Lactose

O

CH2OH

OH

OH

OH

O HOH

O

CH2OH

OH

OH

- GLYCOSIDIC LINK

D - GALACTOSE D - GLUCOSE

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5) TREHALOSE : a non reducing sugar : in insects : contains 2 glucose molecules

POLYSACCHARIDES

GENERALa) most abundant type of carbohydrateb) classification 1) ENERGY - -glycosidic link

2) STRUCTURE AND PROTECTION - -glycosidic link

ENERGY POLYSACCHARIDES

GENERAL - why are these used by the cell?

1) Large molecular weight - large mass1) large aggregates of small MW compounds vrs.2) colloid state found with larger molecules

2) Protection of cell’s colligative properties- the properties of solution are dependent upon the # particles- larger molecules are easier to store (carry around) and also protect against water loss- water balance - osmotic properties of a cell depend upon the number of particles in solution and not the mass of those particles- 1 gram of polysaccharide has the same osmotic properties as a milligram of individual glucose units

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POLYSACCHARIDES

3) PLANT STARCHa) Occurs as granules in cell cytoplasm (30 - 100 nm chains).b) They are heterogenous (molecular similarity). Plant starch is composed of 1 part AMYLOSE and 3 parts AMYLOPECTINE.c) Plant starch composes 60% of our daily caloric intake.

AMYLOSE : composed of D- glucose units joined in 1-4 glycosidic links : polymers of maltose : molecular weight is 60,000 to 1,500,000 daltons

AMYLOPECTINE : structure is not linear: branched (tree-like) with chains of D-glucose units joined in a 1-4 -glycosidic link: branch points of 1-6 a-glycosidic link (anomeric C atom (aldose and ketose C)) - always involves C1

: branching provided by OH on C6

: 25 units per chain: compacts the space taken by many glucose units into a smaller volume

25 units

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POLYSACCHARIDES 4) GLYCOGEN

: animal product and is present in muscle and liver: muscle is a primative sort of tissue with primative energy derivation: it has very large molecular weight (millions): it's structure is similar to amylopectine except that it is more highly branched: the molecules in glycogen are more compact and it has 1 to 6 -glycosidic links: every 8 to 10 units is a D-glycose unit

5) DEXTRANS: form of energy storage in bacteria: it is composed of D-glucose joined via various glycosidic links

STRUCTURAL POLYSACCHARIDES

CELLULOSE: the most abundant natural product and 50 % of all natural organic material in biosphere contain cellulose: has linear chains of D-GLUCOSE units joined via 1-4 -glycosidic links: the polymer of CELLOBIOSE: has the same chemical component of amylose and is involved in structure and rigidity of plant cells (H-bonding between chains): not utilized by mammals except the ruminants (ruminants possess symbiotic microorganisms in lumen): cellulose provides an easy and cheap way to feed cattle

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MUCOPOLYSACCHARIDES

a) Generally occur in association with proteins GLYCOPROTEINS < 4% hexosamine (amino sugars) MUCOPROTEINS > 4% hexosamine

b) Chitin (no protein): N-ACETYL-D-GLUCOSAMINE: units joined via1-4 -glycosidic link: compare to structure of cellulose: exoskeletons of insects and crustaceans: important in pesticide development

c) Mucopolysaccharides have a wide range of activities: Hyaluronic acid, D-Glucuronic acid, N-Acetyl-D-Glucosamine: joined by 1,3 - and 1,4 -glycosidic links: found in cell coat: joint lubricants: blood group factors and blood typing: reflects in surface of red blood cell: an anticoagulant (heparine) is a mucopolysaccharide

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POLYSACCHARIDE DEGRADATION

Generala) polysaccharides undergoes degradation to permit use of constituent monosaccharides (plant starch, glycogen)b) Pathway of degradation varies with cellular location.

Release of monosaccharides1) Extracellular (outside of the cell) hydrolysis eg. D-GLUCOSE

: gastrointestinal tract - still considered outside of the body - cells secrete enzymes to outer body that conduct hydrolysis

: salivary amylase and pancreatic amylase- catalyze the hydrolysis of 1-4 -glycosidic links- amylo-1,6--glucosidase - hydrolysis of any branch

points (1-6 ) - introduction of water

- important to digestion (broken down before being absorbed)

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O

CH2OH

OHOH

OH

O

O

CH2OH

OH

OH

O

O

CH2OH

OHOH

OH

OPO3

=

D- Glucose-1-phosphate

slight

Release of monosaccharides2) Intracellular phosphorolysis

- bond cleavage with phosphoric acid (uses elements of phosphate)

- working from non-reducing end of molecule- nucleophilic attack of phosphate on C1- chopping off at non reducing end (branching points are obstacles)- phosphorilytic degradation of glycogen results in release of D-glucose-1-phosphate- controlled by consumption of the product- enzyme phosphorylase regulated and this system is crutial in deriving energies from energy bank- 2 forms of phosphorylases: a and b

- bond breaking, covalent modification

O

OHO

O

P

Phosphorylase b (inactive)

2 Pi

balance

-

-

Phosphorylase a (active)

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Phosphorylase phosphatase:

: conversion between active and inactive forms: inactive form is in muscle: if using phosphate group from ATP ADP and AMP accumulate (trouble): AMP positively modifies system (changes shape of the phosphatase to make it active): take AMP and use it as an allosteric modifier to convert to an active form: ATP (negative) and AMP (positive) compete for allosteric sites

What turns phosphorylase kinase on?: hormones: ADRENALIN in muscle, GLUCAGON in liver: stimulate the release : ATP upon hormone stimulation releases 2 pyrophosphate: cAMP stimulates the enzyme system and turns the protein kinase inactive to a protein kinase active. The active protein kinase stimulates the phosphorylase kinase.: release of glucose from glycogens creates instant release of energy

Phosphorylase a active Phosphorylase b inactive

2 Pi

Phosphorylase phosphatase

Phosphorylasekinase

2 ATP2 ADP

(+) AMP(-) ATP

allostericmodification

covalentmodification

alwaysoperational

phosphotasecleaves off Pi

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Phosphorylase phosphatase:

cAMPintracellular messenger

ATP AMP + PP (= pyrophosphate)

Protein Kinase (inactive) Protein Kinase (active)

adenylate cyclase cAMP Phosphorylase Kinase

: cAMP stimulates the enzyme system and turns the protein kinase inactive to a protein kinase active: the active protein kinase stimulates the phosphorylase kinase

: How does the system know when to shut down?- by consuming cAMP

upon hormonalstimulation

forms

stimulatescovalent

modification

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C OH

C H

H

OH

CH

CHO

C OHH

OH

CH2OH

OH

OH

CHO

OH

OH

CH2OH

O

CH2OH

H

OH

OH

HOH

OH

H

H

O

CH2OH

H

OH

OH

OH

OH

H

H

O

CH2OH

H

H

OH

OH

OH

H

OH

H

H

H

O

CH2OH

H

OH

OH

OH

H

H

D-Glucopyranose -

O

CH2OHOH

OH

H

OHOH

H

H

H

H

OH

H

O

HH H

OH

H

O

HH

OH

CH2OH

O

H OH

O

H

H

OH

H

H

OH

CH2OH

H

CARBOHYDRATES

1. Structural formulae (eg. D-Glucose)

( Fischer formula)

D-Glucose

2. Biologically important monosaccharides

D-Ribofuranose -D-2-Deoxyribofuranose -D-Fructofuranose -D-Fructopyranose

D-MannopyranoseD-Glucopyranose -D-Galactopyranose

H

(Haworth formula)

H

H

H

H

H

HO

H

(Chair formula)

HOCH2

HO OH

HOCH2

HO H

HOCH2

HO HHO

HO

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O

CH2OH

H

OHOH

OH

H

O

H H

O

CH2OH

H

OH

OH

H OH

H

OH

CH2

H

O

H

OH

OH

H

OH

O

CH2OH

H

OHOH

OH

H

O

HH

OH

CH2OH

O

OH

OH

H

O

CH2OH

H

HOH

HOH

H

O

HOH

OH

CH2OH

O

OH

OH

H

O

CH2OH

H

OHOH

HOH

H

O

H

OH

H

CH2OH

O

H

OH

OH

H

O

CH2OH

H

OHOH

HOH

H

O

H

OH

O

CH2OH

H

H

OH

H

O

CH2OH

H

OHOH

OH

H

O

H

H

H

H

H

H

H

H

H

H

HH

H

H

H

H

H

H

HOH2C

3. BIOLOGICALLY IMPORTANT DISACCHARIDES

MALTOSE

(4-O--D-GLUCOPYRANOSYL-D-GLUCOPYRANOSE)

ISOMALTOSE

(6-O--D-GLUCOPYRANOSYL-D-GLUCOPYRANOSE)

CELLOBIOSE

(4-O--D-GLUCOPYRANOSYL-D-GLUCOPYRANOSE)

LACTOSE

(4-O--D-GALACTOPYRANOSYL-D-GLUCOPYRANOSE)

TREHALOSE

(-D-GLUCOPYRANOSYL--D-GLUCOPYRANOSIDE)

SUCROSE

(-D-GLUCOPYRANOSYL--D-FRUCTOFURANOSIDE)

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Study sheet- key words

1. Aldoses

2. ketoses

3. D- sugars

4. No. of stereoisomers

5. Reducing sugars

6. Mutarotation

7. Hemiacetals

8. Anomers ( a and b)

9. Pyranoses

10. Furanoses

11. Glycosides (acetals)

12. D- Glucopyranose

13. D- Galactopyranose

14. D- Glucuronic acid

15. D- Galacturonic acid

16. D- Glucosamine

17. D- Galactosamine

18. Maltose

19. Isomaltose

20. Cellobiose

21. Sucrose

22. Lactose

23. Storage Polysaccharides

24. glycogen

25. Starch

26. Amylose

27. Amylopectine

28. Dextran

29. Structural Polysaccharides

30. Cellulose

31. Chitin

32. Mucopolysaccharides

33. Glycogenolysis

34. Glycolysis

35. Control Sites

36. ATP Requirements

37. ATP Production

38. Anaerobic Glycolysis (all steps)

39. Lactate

40. Ethanol

41. Aerobic ATP Formation from glycolysis

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