A Road Map for Cellular RespirationCytosol

Mitochondrion

High-energyelectronscarriedby NADH

High-energyelectrons carriedmainly byNADH

Glycolysis

Glucose2

Pyruvicacid

KrebsCycle

ElectronTransport

Fate of Pyruvate

2 Pyruvic acid

Overview of Glycolysis

Glycolysis: 1

Phosphoryl transfer reaction. Kinases transfer phosphate from ATP to an acceptor. Hexokinase has a more general specificity in that it can transfer phosphate to other sugars such as mannose.

Phosphate group added to #6 carbon from the ATP

ENZYME-

Hexo – substrate

kin – transfer P b/t substate and ATP/ADP

ase - enzyme

The name of the molecule

phosphate on #6 carbon

Step 1- add phosphate to #6 C

Isomerizationby phosphoglucose isomerase

The enzyme opens the ring, catalyzes the isomerization, and promotes the closure of the five member ring.

GLUCOSE

Aldose sugar

An aldehyde with C=O on end C

FRUCTOSE

ketose sugar

A ketone with C=O on a middle C

Step 2- glucose fructose

Glucose to fructose - isomerization

aldose ketose

Changed the structure – moved the carbonyl (C=O) from #1 C to #2 C.An isomer

ENZYME- Hexo – phosphohexoseisomer – 6 member ring to 5 member ringase - enzyme

Step 2- again

Adding another phosphate

The 2nd investment of an ATP in glycolysis.

Step 3- add phosphate to #1 C

Name of the moleculeFructose – 5 member ringPhosphate on #1 and # 6 carbons

ENZYME- phosphofructo – substatekin – transfer P b/t substate and ATP/ADPase - enzyme

Cleavage to two triose phosphates

Enzyme: aldolasealdolase C=O on the end –

a aldehydye

C=O is on the #1 C

C=O in middle – a ketone

Dihydroxy – two OH (except phosphate in second OH spot

Step 4- break 6C into two 3C sugars

Cleavage of six-carbon sugar: step 4 againshows where the cut is made and why two different sugars result

This one will not go down the pathway – that would be a waste of half the original glucose.

STOP!!!

This one will go down the pathway – the enzymes are shape specific.

GO!!!

Salvage of three-carbon fragmentketone aldehyde

Step 5- moving the carbonyl - isomerization

Glycolysis: 3

Done in two steps – this shows the overall result

glyceraldehyde 3-phosphate 1,3 bisphosphoglycerate

Step 6- adding another phosphate w/o using ATP!!!!

ENZYME- Glyceraldehyde 3-phosphate– substratedehydrogen – hydrogen removed and replaced by phosphatease - enzyme

Phosphate from

cytoplasm

Stage 3: The energy yielding phase.

Step 6- adding another phosphate w/o using ATP!!!!

An aldehyde is oxidized to carboxylic acid and inorganic phosphate is transferred to form acyl-phosphate. NAD+ is reduced to NADH.

Note, under anaerobic conditions NAD+ must be re-supplied. With oxygen and mitochondria, NADH will go down electron transport chain and generate ATP.

The two steps.

Aldehyde Acid

Step 7Substrate-level phosphorylation

Phosphate group moved from the substrate to ADP generating an ATP.Kinase enzyme involved in the change

At this point 2ATPs were invested and 2ATPs are produced.

Step 7- moving the phosphate group from substrate to ADP

Step 8: Phosphate shift setup

Step 8- moving the phosphate group from #3 to #2 C

ENZYME- phosphoglycerate– substratemut – changes the structure (sorry not isomerase)ase - enzyme

Step 8- moving the phosphate group from #3 to #2 C

Generation of second very high energy compound by a

dehydration reaction

Step 9- forming an enol with a double bond

between carbons

Dehydration reaction

the energy is locked into the high energy unfavorable enol configuration C=C with OH group

alkene alcohol

An enol phosphate is formed: step 9

Dehydration elevates the transfer potential of the phosphoryl group, which traps the molecule in anunstable enol form

Enol: molecule with hydroxyl group next to double bond

Step 10: Formation of Pyruvate & ATP

ENZYME- pyruvate– substratekin– phosphate transfer between substrate and ATP/ADPase - enzyme

Step 10- forming pyruvate

•Substrate level phosphorylation is the synthesis of ATP from ADP that is not linked to the electron transport system.

Pyruvate Kinase2nd example of substrate level phosphorylation.

The net yield from glycolysis is 2 ATPunstable enol form more stable ketone form

Diverse fates of pyruvate

To citric acid cycle

In anaerobic yeast, pyruvate→ethanol

Pyruvate is decarboxylated.

Acetaldehyde is reduced.

ATP