Download Repetition Summary of last lecture Energy Cell Respiration

3/29/16
Energy
flowsintoanecosystemassunlightandleavesitasheat
Light ener gy
Repetition
ECOSYSTEM
Summary of last lecture
Photos y nthe s is
i n c h l o ro p l as ts
CO2 + H2O
Ce llula r re s pira tion
i n mi to c h o n d ri a
Org a n i c
+ O2
mo l e c u l e s
ATP
pow er s m ost
cel l ul ar w or k
Heat ener gy
Aerobic oxidation of pyruvate and fatty acids in mitochondria
Cell Respiration
There are three mainprocessesinthismetabolicenterprise
CYTOSOL
El e c tro n sh uttle s
s p a n me mb ra ne
MITOCHONDRION
2 NADH
or
2 FADH2
2 NADH
2 NADH
Gly c oly s is
Gl u c o s e
2
Py ru v a te
2
Acet yl
CoA
+ 2 ATP
b y s u b s tra te-l e ve l
p h o s p h o ry l ati on
Ma x i mu m p e r g l u c o s e:
6 NADH
Citric
a c id
c y c le
2 FADH2
O xi dat i ve
phosphor yl at i on:
el ect r on t r anspor t
and
chem i osm osi s
+ 2 ATP
+ a b o u t 3 2 o r 34 ATP
b y s u b stra e
t -le ve lb y o x i d ati ve p ho sp ho ryl ati on , d ep en di n g
phos phoy
ra
l tio n o n wh i c h sh uttle tra ns po rts e l ectro ns
fro m NADH i n c yto so l
Ab o u t
3 6 o r 3 8 ATP
The out er m em br ane is f r eely per m eable
t o all m et abolit es,
but specif ic
t r anspor t pr ot eins
( color ed ovals)
in t he inner m em br ane ar e r equir ed t o im por t pyr uvat e
( yellow) ,
ADP ( gr een) , and Pi ( pur ple) int o t he m at r ix and t o expor t ATP ( gr een) . NADH
gener at ed in t he cyt osol is not t r anspor t ed dir ect ly
t o t he m at r ix because
+
+
t he inner m em br ane is im per m eable
t o NAD and NADH;
inst ead,
a shut t le syst em ( r ed) t r anspor t s elect r ons
f r om cyt osolic
NADH
t o NAD in t he m at r ix. O 2
dif f uses int o t he m at r ix and CO 2 dif f uses out . St age- 1:
special car r ier ( blue oval)
and t hen r eat t ached t o CoA
• About 40% of the energy in a glucose molecule is transferred to
ATP during cellular respiration, making approximately 38 ATP
( at t ached t o CoA)
ar e also
conver t ed t o acet yl CoA
f at t y acyl gr oups
ar e t r ansf er r ed f r om f at t y acyl CoA and t r anspor t ed acr oss t he inner m em br ane via a
on t he m at r ix side. Pyr uvat e is conver t ed t o acet yl CoA wit h t he f or m at ion of NADH,
and f at t y acids
wit h f or m at ion of NADH
and FADH2.
O xidat ion
of acet yl CoA in t he cit r ic
FADH2.
St age- 2:
elect r ons
f r om t hese r educed coenzym es
ar e t r ansf er r ed via elect r on t r anspor t com plexes
ions f r om t he m at r ix t o t he int r am em br ane space, gener at ing t he pr ot on- m ot ive f or ce. Elect r ons
f r om NADH
com plex
ar r ows
I I . St age 3: ATP synt hase,
t r ansm em br ane
m ovem ent
t he F0F1 com plex
( or ange) ,
of pr ot ons; and gr een ar r ows
har nesses
indicat e
t he pr ot on- m ot ive
t r anspor t
acid cycle gener at es
NADH
and
+
( blue boxes) t o O 2 concom it ant wit h t r anspor t of H
f low dir ect ly f r om com plex
I t o com plex I I I , bypassing
f or ce t o synt hesize
ATP.
Blue ar r ows
indicat e
elect r on f low;
r ed
of m et abolit es.
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TypesofFermentation
2 ADP
+ 2
P1
2 ATP
(ATP without the use of oxygen)
• Fermentationconsists of
G lucose
C
2 ADP
2 Acet aldehyde
+ 2
P1
O
C
C
Am ino
O–
2 NADH
C
O
C
O
Sugar s
G lycer ol
Fat t y
acids
G l ycol ysi s
Funnel electrons from many
kinds of organic molecules
into cellular respiration
–
Fat s
Car bohydr at es
acids
• Catabolic pathways
2 ATP
G lycolysis
2 NAD+
H
TheVersatility ofCatabolism
f er m ent at i on
G lucose
• During lactic acid fermentation
CO 2
O
CH3
( a) Al cohol
• In alcohol fermentation
2
H
OH
CH3
pyruvate is reduced
directly to NADH to form
lactate as a waste product
Pr ot ei ns
2 NADH
H
C
2 Et hanol
–
O
2 Pyr uvat e
2 NAD+
H
pyruvate is converted to
ethanol in two steps, one
of which releases CO 2
O
C
CH3
• - glycolysis plus reactions that
regenerateNAD +, which canbe
reused byglyocolysis
–
• Glycolysisandthecitricacidcycleconnecttomany
othermetabolicpathways
O –
C
G lycolysis
Gl u c o s e
G lycer aldehyde- 3-
NH3
P
Py ru v a te
• The catabolism of various
molecules from food
Acet yl CoA
Ci t r i c
CH3
aci d
cycl e
O
OH
CH3
2 Lact at e
O xi dat i ve
phosphor yl at i on
( b) Lact i c aci d f er m ent at i on
• Steroid hormonesbindtointracellular receptors
Cell Signalling –
HormoneSignalling
(a ligand)
Ho rmo n e
(te s to s tero ne )
EXTRACEL LU LA R
FLUI D
Pl a s ma
me mb ra n e
1
The steroid hormone testosterone
passes through the plasma
membrane.
2
Testosterone binds to a receptor
protein in the cytoplasm, activating
it.
Re c e p to r
p ro te i n
Ho rmo n e re c e p to r
c o mp l e x
3
The hormone- receptor complex
enters the nucleus
and binds to specific genes.
DNA
4
mRNA
NUCL EUS
The bound protein stimulates the
transcription of the gene into mRNA.
Ne w p ro te i n
5
The mRNA is translated into a
specific protein.
CYTOPL ASM
2
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1
CellSignalling – ReceptorsinthePlasmaMembrane
Signalling
• maintypesofmembranereceptors
A signal m olecule
t o a r ecept or , leading
Calcium
act ivat ion
2
binds
to
of phospholipase
Phospholipase
plasm a
C.
EXTRACEL L UL AR
FL UID
called
C cleaves
3
a
DAG f unct ions as
a second
m em br ane phospholipid
PI P2 int o DAG
m essenger
in ot her pat hways.
and I P3.
Si g n a l mo l e c u e
l
(fi rs t me s s e n g er)
G p ro te i n
DAG
(d i a c y l g l yc e rol )
G TP
PIP2
G-p ro te i n -l i n k e d
re c e p to r
• G-protein-linked
Ph o s p h o l i p as e C
I P3
( second m essenger )
IP3-g a te d
c a l c i u m c h a nn e l
• Tyrosinekinases
En d o p l a s mi c
re ti c u l u m (ER)
• Ion channel
Va ri o u s
p ro te i n s
a c ti v a te d
Ca 2+
Ce l l u l a r
re s p o n s e
Ca 2+
(s e c o n d
me s s e n g e r)
4
I P3 quickly dif f uses t hr ough
t he cyt osol and binds
t o an I P3–
gat ed calcium
m em br ane,
Gro wth fa c to r
• Other pathways
• regulategenes
byactivating
transcription
factorsthat
turn geneson
or off
Re c e ption
Re c e p to r
channel
causing
in t he ER
it t o open.
• Ionchannelreceptors
5
6
Calcium o
i ns f low out of
t he ER ( down t heir con-
The calcium
act ivat e t he next
cent r at ion gr adient ) , r aising
2+
t he Ca
level in t he cyt osol.
Si g n a l
mo l e c u l e
(l i g a n d )
Ga te c l o s e d
L i g a n d -g a te d
i o n c h a n n e l re ce p to r
Ph o s p h o ryl ati on
c as c ade
ions
pr ot ein n
i one or m or e
signaling
pat hways.
Io n s
Pl a s ma
Me mb ra n e
Tra ns duc tion
Ga te o p e n
CYTOPL ASM
In a c ti v e
tra n s c ri p ti o n
fa c to r
Ac ti v e
tra n s c ri p ti o n
fa c to r
Ce l l u l a r
re s p o n s e
P
Re s pons e
DNA
Ga te c l o s e
Ge n e
NUCL EUS
mRNA
3