Download Ch 9 and 11 Review Slides

Resp & Cell Comm Review
Two main catabolic processes:
• fermentation: partial degradation of sugars in the
absence of oxygen.
• cellular respiration: uses oxygen to complete the
breakdown of many organic molecules.
• more efficient and widespread
• Most steps occur in mitochondria.
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Introduction
• Photosynthetic organisms
store energy in organic
molecules.
• These are available to…
• themselves, and …
• others that eat them.
Fig. 9.1
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2. Cells recycle the ATP they use for work
• ATP (adenosine triphosphate):
• chemical equivalent of a loaded spring.
• trio of PO4- groups are unstable, high-energy.
• ATP  ADP + PO4
powers most cellular work
• ATP must be constantly recycled from ADP and PO4
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• What’s different in the electron sharing of the
reactants vs. the products?
• Where does this energy come from?
• Which atoms got oxidized/reduced?
Fig. 9.3
high energy e- positions
low energy e- positions
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glycolysis, the Krebs cycle, the electron
transport chain, and chemiosmosis via
ATP synthase & H+ gradient.
• substrate-level phosphorylation generates the few
ATP’s produced in glycolysis and the Krebs cycle.
• How is this different
from oxidative
phosphorylation?
• no e- transport
chain.
Fig. 9.7
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• energy investment phase: 2 ATP create reactants with
high free energy by phosphorylating glucose.
• energy payoff phase:
BIG PICTURE
• 4 ATP via substratelevel phosphorylation
• NAD+ is reduced
to NADH.
• Net Production?
• 2 ATP + 2 NADH
• 2 pyruvate
• NOT used?
• O2
Fig. 9.8
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• More than ¾ of the original energy in one glucose is
still present in two molecules of pyruvate.
Fig. 9.10
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• For each
Acetyl CoA
that goes in...
• Lots of high energy
electron carriers are
produced…
Know
THIS
one!
• Net of 2 NADH
• 1 FADH2
• Also produced?
• one ATP
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Fig. 9.12
• electron transport
chain:
• Thousands of copies in
the cristae of each
mitochondrion.
• Most parts are proteins
that accept electrons, then
pass them along.
• Electrons drop in free
energy as they pass down
the chain.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Note the location!
Note what is being pumped!
+ 2 H+
Fig. 9.15
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• ATP synthase in the cristae
makes ATP from ADP & Pi.
• osmos – “to push”
• chemiosmosis*: using a
chemical’s “push”
• Push of H+ gradient powers
ATP synthase
•
http://www.youtube.com/watch?v=xbJ0nbzt5Kw
•
•
start at 40 seconds, watch next 3:10
http://www.youtube.com/watch?v=FFBr3ANCkb4
•
5 min of Ninja Respiration fun!
* vs. substrate level
phosphorylation
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Fig. 9.14
Big Picture
Fig. 9.16
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• alcohol fermentation:
• performed by yeast; used in brewing and winemaking.
Fig. 9.17a
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• lactic acid fermentation:
• Lactic acid fermentation by some fungi and bacteria is used
to make cheese and yogurt.
• Muscle cells switch from aerobic respiration to lactic acid
fermentation to generate ATP if O2 is scarce.
• lactate is converted
back to pyruvate in
the liver.
Fig. 9.17b
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• Some organisms (facultative anaerobes), including
yeast and many bacteria, can survive using either
fermentation or respiration.
• human muscle cells too.
Fig. 9.18
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Fig. 9.19
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• ex: phosphofructokinase
catalizes 3rd glycolysis step
• high ATP levels  enzyme
inhibition
• high ADP/AMP levels  enzyme
activation.
• inhibition by citrate slows
glycolysis until Krebs cycle “catches
up”.
Fig. 9.20
Chapter 11
Cell Communication
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Evolution of Cell Signaling
• Yeast cells
– Identify their
mates by cell
signaling
1 Exchange of
mating factors.
Each cell type
secretes a
mating factor
that binds to
receptors on
the other cell
type.
2 Mating. Binding
of the factors to
receptors
induces changes
in the cells that
lead to their
fusion.
 factor
Receptor

a
Yeast cell,
mating type a
 factor

a
3 New a/ cell.
Figure 11.2
The nucleus of
the fused cell
includes all the
genes from the
a and a cells.
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Yeast cell,
mating type 
a/
• In local signaling, animal cells
– May communicate via direct contact
Figure 11.3 (b) Cell-cell recognition. Two cells in an animal may communicate by interaction
between molecules protruding from their surfaces.
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• In other cases, animal cells
– Communicate using local regulators
Local signaling
Target cell
Electrical signal
along nerve cell
triggers release of
neurotransmitter
Neurotransmitter
diffuses across
synapse
Secretory
vesicle
Local regulator
diffuses through
extracellular fluid
(a) Paracrine signaling.
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Target cell
is stimulated
(b) Synaptic signaling
• In long-distance signaling
Long-distance signaling
Endocrine cell
– Both plants and animals
use hormones
– Why do only certain
cells respond?
Blood
vessel
Hormone travels
in bloodstream
to target cells
Target
cell
Figure 11.4 C
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(c) Hormonal signaling. Specialized
endocrine cells secrete hormones
into body fluids, often the blood.
Hormones may reach virtually all
body cells.
• Overview of cell signaling
EXTRACELLULAR
FLUID
1 Reception
CYTOPLASM
Plasma membrane
2 Transduction
3 Response
Receptor
Activation
of cellular
response
Relay molecules in a signal transduction pathway
Signal
molecule
Figure 11.5
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• G-protein-linked receptors
Signal-binding site
Some good animations
Segment that
interacts with
G proteins
G-protein-linked
Receptor
Plasma Membrane
Activated
Receptor
Signal molecule
GDP
CYTOPLASM
G-protein
(inactive)
Enzyme
GDP
GTP
Activated
enzyme
GTP
GDP
Pi
Figure 11.7
Cellular response
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Inactive
enzyme
• Receptor tyrosine kinases – what’s happening?
Signal-binding sitea
Signal
molecule
Signal
molecule
Helix in the
Membrane
Tyr
Tyrosines
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Tyr
Receptor tyrosine
kinase proteins
(inactive monomers)
CYTOPLASM
Tyr
Dimer
Activated
relay proteins
Figure 11.7
Tyr
P Tyr
P Tyr
Tyr P
Tyr P
Tyr
P Tyr
Tyr P
Tyr
Tyr
Tyr
Tyr
6
ATP
Activated tyrosinekinase regions
(unphosphorylated
dimer)
6 ADP
Fully activated receptor
tyrosine-kinase
(phosphorylated
dimer)
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P Tyr
P Tyr
P Tyr
Tyr P
Tyr P
Tyr P
Inactive
relay proteins
Cellular
response 1
Cellular
response 2
Signal
molecule
(ligand)
• Ion channel receptors
– critical in nerve cells
Gate closed
Ligand-gated
ion channel receptor
Ions
Plasma
Membrane
Gate open
Cellular
response
Gate close
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Figure
11.7
• A phosphorylation cascade
Signal molecule
Receptor
Activated relay
molecule
Inactive
protein kinase
1
1 A relay molecule
activates protein kinase 1.
2 Active protein kinase 1
transfers a phosphate from ATP
to an inactive molecule of
protein kinase 2, thus activating
this second kinase.
Active
protein
kinase
1
Inactive
protein kinase
2
ATP
Pi
PP
Inactive
protein kinase
3
5 Enzymes called protein
phosphatases (PP)
catalyze the removal of
the phosphate groups
from the proteins,
making them inactive
and available for reuse.
Figure 11.8
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P
Active
protein
kinase
2
ADP
3 Active protein kinase 2
then catalyzes the phosphorylation (and activation) of
protein kinase 3.
ATP
ADP
Pi
Active
protein
kinase
3
PP
Inactive
protein
P
4 Finally, active protein
kinase 3 phosphorylates a
protein (pink) that brings
about the cell’s response to
the signal.
ATP
ADP
Pi
PP
P
Active
protein
Cellular
response
1 A signal molecule binds
2 Phospholipase C cleaves a
to a receptor, leading to
plasma membrane phospholipid
activation of phospholipase C. called PIP2 into DAG and IP3.
•
“2nd
Messenger”
is a general term,
it may actually be
applied to a 3rd
or 4th messenger.
EXTRACELLULAR
FLUID
3 DAG functions as
a second messenger
in other pathways.
Signal molecule
(first messenger)
G protein
DAG
GTP
PIP2
G-protein-linked
receptor
Phospholipase C
IP3
(second messenger)
IP3-gated
calcium channel
Endoplasmic
reticulum (ER)
Various
proteins
activated
Ca2+
Cellular
response
Ca2+
(second
messenger)
Figure 11.12
4 IP3 quickly diffuses through
the cytosol and binds to an IP3–
gated calcium channel in the ER
membrane, causing it to open.
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5 Calcium ions flow out of
the ER (down their concentration gradient), raising
the Ca2+ level in the cytosol.
6 The calcium ions
activate the next
protein in one or more
signaling pathways.
Reception
Binding of epinephrine to G-protein-linked receptor (1 molecule)
• Amplification of a
transduced signal:
Transduction
Inactive G protein
Active G protein (102 molecules)
Inactive adenylyl cyclase
Active adenylyl cyclase
(102)
ATP
Cyclic AMP (104)
Inactive protein kinase A
Active protein kinase A (104)
Inactive phosphorylase kinase
Active phosphorylase kinase (105)
Inactive glycogen phosphorylase
Active glycogen phosphorylase (106)
Response
Figure 11.13
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Glycogen
Glucose-1-phosphate
(108 molecules)
Growth factor
Reception
Receptor
• Many pathways
regulate genes
by activating
transcription
factors that turn
genes on or off
Phosphorylation
cascade
Transduction
CYTOPLASM
Inactive
transcription Active
factor
transcription
factor
P
Response
DNA
Gene
NUCLEUS
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mRNA
• Branching and
“cross-talk”
further help the
cell coordinate
incoming signals
Signal
molecule
Cell A. Pathway leads
to a single response
Receptor
Relay
molecules
Response 1
Response Response
2
Cell B. Pathway branches,
leading to two responses
3
Cell C. Cross-talk occurs
between two pathways
Activation
or inhibition
Response 4
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Response 5
Cell D. Different receptor
leads to a different response
Signaling Efficiency: Scaffolding Proteins and
Signaling Complexes
• Scaffolding proteins
– Can increase the signal transduction efficiency
Signal
molecule
Plasma
membrane
Receptor
Scaffolding
protein
Figure 11.16
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Three
different
protein
kinases