Glycolysis andCellular Respiration

A quick review on Cellular Energetics

By Noel Ways

ADP

ATP NADH

NAD+

NADH

NAD+

e-

H2OO2

Glucose

Pyruvate

ATP

A

B

C

D

E

F

G

etc.

e-e-

e-e-

e-e-

e-

e-H

+

CO

2 + H

2OSu

gar

H2O

O

2

e-H

+

CO

2 + H

2O

O2

H2O

Hig

h En

ergy

Low

Ene

rgy

AD

P +

P

ATP

AB B

A

e e

e e

A is

Oxi

dize

d

Red

uced

A

Red

uced

BO

xidi

zed

A

Oxi

dize

d B

B is

Red

uced

From

Tex

t, Fi

g 5.

6

2e- H

+2e

- H+

NA

DH

NA

D+

Figu

re 1

Figu

re 2

Figu

re 3

Figu

re 4

Page

2

Cytoplasm

Mitochondria

Acetyl CoA

Citric Acid

CoA

CoA

NAD+CO2

NADHPyruvate

NAD+NADH

NADH

ADPATP

CO2CO2

NAD+

FAD

NADHFADH2

NADH

NAD+

2

+++ +

Cytoplasm

Matrix of Mitochondria

Electro-chemicalGradient in Intermembrane Space

pH 3 differencefrom Matix.(H+ 1000x)

NAD+ FAD

FADH2 H20O2

ADP + P

ATP

NADH NAD+ NADH NAD+NADH NAD+ NADH

NADH

NAD+

NAD+

e- e-

e-

+ ++++

++

++++ +

++++++++++

++ +

++ ++ ++++

+ + + +++ +

+ ++ +

e-ATP

Synthase

N.R.

N.R.

F.R.

F.R.

Substrate LevelPhosphorylation

SLP

O/R

O/R

O/R

O/R

O/R

S/M

S/M

S/M

M

ATP Score Sheet

Be able to fill in from a properly drawn illustration.

ADP

ATP

ADP

ADP

ATP

ADP

ATP

ADP

ATP

ADP

NADH

NAD+

Glucose

Pyruvate

2

SLP

SLP

O/R

P

P P

PP

P

P

P

P

Phos

Phos

GLYCOLYSIS

TRANSITION STAGE

ELECTRON TRANSPORTCHAIN

KREB’S CYCLE

Gly

coly

sis a

nd C

ellu

lar R

espi

ratio

n fu

nctio

n to

con

-ve

rt gl

ucos

e (u

sele

ss fo

r cel

lula

r wor

k) in

to A

TP, t

he

only

use

ful e

nerg

y fo

rm fo

r liv

ing

thin

gs.

Bro

adly

, th

is e

nerg

y tra

nsfo

rmat

ion

proc

ess c

an b

e br

oken

dow

n in

to fo

ur e

ssen

tial s

teps

.

Gly

coly

sis i

s the

firs

t ste

p. T

his s

tep

occu

rs in

the

cyto

plas

m.

Her

e th

ere

is

a ne

t gai

n of

two

ATP.

Als

o, N

AD

+ is

re

duce

d to

NA

DH

, whi

ch is

to sa

y it

now

is “

hold

ing”

two

“hig

h en

ergy

el

ectro

ns”.

The

se e

lect

rons

will

be

used

to g

ener

ate

mor

e ATP

with

the

“ele

ctro

n tra

nspo

rt ch

ain”

.

Dur

ing

Gly

coly

sis,

the

gluc

ose

will

ha

ve b

een

brok

en d

own

into

two

mol

-ec

ules

of p

yruv

ate.

Gly

coly

sis

Page

4

Onc

e py

ruva

te is

fo

rmed

, it e

nter

s int

o th

e M

ITO

CH

ON

DR

IA,

whe

re it

is “

trans

ition

ed”

into

a c

yclic

al se

t of r

eact

ions

ca

ll th

e K

reb’

s Cyc

les.

Alth

ough

ther

e is

no

ATP

prod

uctio

n du

ring

the

trans

i-tio

n st

age,

NA

D+

is re

duce

d an

d w

ill a

gain

be

used

to c

arry

“h

igh

ener

gy e

lect

rons

” to

the

“ele

ctro

n tra

nspo

rt ch

ain,

w

here

sign

ifica

tion

ATP

pro-

duct

ion

occu

rs.

Page

5

Rec

all t

hat d

urin

g th

is st

age,

a C

O2

is lo

st a

nd

this

resu

lts in

an

acet

yl g

roup

, whi

ch is

atta

ched

to

a C

oenz

yme A

(ace

tyl C

oA).

The

ace

tyl

grou

p is

now

inco

rpor

ated

into

the

Kre

bs’

Cyc

le.

Tran

sitio

n St

age

The

Kre

b’s C

ycle

is

a cy

clic

al se

t of r

eac-

tions

, tha

t in

a se

quen

tial

man

ner,

mod

ifies

and

bre

aks

dow

n th

e or

gani

c co

mpo

unds

“f

ed”

into

it.

In th

is p

roce

ss,

subs

tant

ial “

high

ene

rgy

elec

trons

” ar

e “h

arve

sted

” by

w

ay o

f NA

D+

bein

g re

duce

d to

NA

DH

. Th

ese

elec

trons

w

ill a

gain

be

fed

into

the

“Ele

ctro

n Tr

ansp

ort C

hain

” an

d fo

r ATP

gen

erat

ion

pur-

pose

s.Pa

ge 6

Rec

all t

hat d

urin

g th

is p

ro-

cess

, CO

2 is

libe

rate

d (a

nd

will

subs

eque

ntly

be

exha

led)

, and

that

two

ATP

are

gene

rate

d. I

n ad

ditio

n,

FAD

is re

duce

d to

FA

DH

2,

and

will

like

wis

e de

liver

el

ectro

ns to

the

elec

tron

trans

port

chai

n.

Kre

b’s C

ycle

The

elec

tron

trans

-po

rt ch

ain

cons

ists

of

a se

ries o

f mol

ecul

es th

at

rece

ives

the

“hig

h en

ergy

el

ectro

ns”.

The

se e

lect

rons

w

ill b

e al

low

ed to

go

to

low

er e

nerg

y st

ates

, and

the

ener

gy re

leas

ed w

ill b

e us

ed

to g

ener

ate

muc

h AT

P. A

t th

e en

d of

the

line,

the

now

“l

ow e

nerg

y el

ectro

ns”

will

be

rece

ived

by

O2

as w

aste

, an

d th

e ox

ygen

will

be

redu

ced

to w

ater

. O

xyge

n is

th

e fin

al e

lect

ron

acce

ptor

an

d is

the

only

reas

on w

e ne

ed o

xyge

n.Pa

ge 7

Rec

all t

hat d

urin

g th

is p

roce

ss, t

he e

nerg

y re

leas

ed b

y th

e el

ec-

trons

goi

ng to

low

er e

nerg

y st

ates

will

be

used

to p

ump

H+

into

th

e in

term

embr

ane

spac

e. T

his w

ill g

ener

ate

an “

elec

troch

emi-

cal g

radi

ent”

whi

ch w

ill d

rive A

TP p

rodu

ctio

n. A

s the

hyd

ro-

gens

retu

rn to

the

mito

chon

dria

l mat

rix th

roug

h AT

P sy

ntha

se,

ATP

will

be

prod

uced

.

Elec

tron

Tra

nspo

rt C

hain