Download - ap bio power point ch. 11
-
7/24/2019 ap bio power point ch. 11
1/37
Evolution of Cell Signaling
A signal transduction pathway is a series ofsteps by which a signal on a cells surface isconverted into a specific cellular response
-
7/24/2019 ap bio power point ch. 11
2/37
Local and Long-Distance Signaling
Cells in a multicellular organism communicateby chemical messengers
Animal and plant cells have cell junctions that
directly connect the cytoplasm of adjacent cells
In local signaling, animal cells may
communicate by direct contact, or cell-cell
recognition
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
-
7/24/2019 ap bio power point ch. 11
3/37
Fig !!-"
Plasma membranes
Gap junctionsbetween animal cells
(a) Cell junctions
Plasmodesmatabetween plant cells
(b) Cell-cell recognition
-
7/24/2019 ap bio power point ch. 11
4/37
In many other cases, animal cells communicateusing local regulators, messenger molecules
that travel only short distances
In long-distance signaling, plants and animalsuse hormones
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
-
7/24/2019 ap bio power point ch. 11
5/37
Fig !!-#
Local signaling
Target cell
Secretingcell
Secretoryvesicle
Local regulator
diuses through
e!tracellular luid
(a) Paracrine signaling (b) Synaptic signaling
Target cell
is stimulated
"eurotransmitter
diuses across
synapse
#lectrical signal
along nerve cell
triggers release o
neurotransmitter
Long-distance signaling
#ndocrine cell $loodvessel
%ormone travelsin bloodstreamto target cells
Targetcell
(c) %ormonal signaling
-
7/24/2019 ap bio power point ch. 11
6/37
The Three Stages of Cell Signaling:A Preview
Cells receiving signals go through threeprocesses$
&eception
Transduction &esponse
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
-
7/24/2019 ap bio power point ch. 11
7/37
Fig !!-%-!
&eception'
#T&C#LL*L&+L*,
Signalingmolecule
Plasma membrane
C.T/PLS0
'
&eceptor
-
7/24/2019 ap bio power point ch. 11
8/37
Fig !!-%-&
'
#T&C#LL*L&+L*,
Signalingmolecule
Plasma membrane
C.T/PLS0
Transduction1
&elay molecules in a signal transduction pathway
&eception'
&eceptor
-
7/24/2019 ap bio power point ch. 11
9/37
Fig !!-%-'
#T&C#LL*L&+L*,
Plasma membrane
C.T/PLS0
&eceptor
Signalingmolecule
&elay molecules in a signal transduction pathway
ctivationo cellularresponse
Transduction &esponse1 2&eception'
-
7/24/2019 ap bio power point ch. 11
10/37
https$((wwwyoutubecom(watch)v*+dn!./01A
-
7/24/2019 ap bio power point ch. 11
11/37
Reception: A signal molecule binds to a receptorprotein, causing it to change shape
2he binding between a signal molecule3ligand4 and receptor is highly specific
A shape change in a receptor is often the initial
transduction of the signal
5ost signal receptors are plasma membrane
proteins
-
7/24/2019 ap bio power point ch. 11
12/37
Receptors in the lasma !embrane
2here are three main types of membranereceptors$
6 protein-coupled receptors
7eceptor tyrosine 8inases Ion channel receptors
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
!!
-
7/24/2019 ap bio power point ch. 11
13/37
Fig !!-9b
G protein-coupledreceptor
Plasmamembrane
#n3ymeG protein(inactive)
GP
C.T/PLS0
ctivateden3yme
GTP
Cellular response
GP
P i
ctivatedreceptor
GP GTP
Signaling molecule,nactiveen3yme
' 1
2 4
-
7/24/2019 ap bio power point ch. 11
14/37
Fi !! 9d
-
7/24/2019 ap bio power point ch. 11
15/37
Fig !!-9d
Signaling
molecule
(ligand)
Gateclosed ,ons
Ligand-gatedion channel receptor
Plasmamembrane
Gate open
Cellularresponse
Gate closed2
1
'
-
7/24/2019 ap bio power point ch. 11
16/37
"ntracellular Receptors
:ome receptor proteins are intracellular, foundin the cytosol or nucleus of target cells
:mall or hydrophobic chemical messengers
can readily cross the membrane and activatereceptors
;+amples of hydrophobic messengers are the
steroid and thyroid hormones of animals
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig !! < !
-
7/24/2019 ap bio power point ch. 11
17/37
Fig !!-
-
7/24/2019 ap bio power point ch. 11
18/37
Fig !!-
-
7/24/2019 ap bio power point ch. 11
19/37
Fig !!-
-
7/24/2019 ap bio power point ch. 11
20/37
Fig !!-
-
7/24/2019 ap bio power point ch. 11
21/37
http$((bcswhfreemancom(thelifewire(content(chp!#(!#=&=html
-
7/24/2019 ap bio power point ch. 11
22/37
Transduction: Cascades of molecular interactionsrela# signals from receptors to target molecules in
the cell :ignal transduction usually involves multiple
steps
5ultistep pathways can amplify a signal$ A fewmolecules can produce a large cellular
response
5ultistep pathways provide more opportunitiesfor coordination and regulation of the cellular
response
-
7/24/2019 ap bio power point ch. 11
23/37
rotein hosphor#lation and Dephosphor#lation
In many pathways, the signal is transmitted by acascade of protein phosphorylations
Protein 5inases transfer phosphates from A2 to
protein, a process called phosphorylation
Protein phosphatases remove the phosphates
from proteins, a process called dephosphorylation
2his phosphorylation and dephosphorylationsystem acts as a molecular switch, turning
activities on and off
-
7/24/2019 ap bio power point ch. 11
24/37
Small !olecules and "ons as Second !essengers
2he e+tracellular signal molecule that binds tothe receptor is a pathways >first messenger?
Second messengers are small, nonprotein,
water-soluble molecules or ions that spreadthroughout a cell by diffusion
Cyclic A5 and calcium ions are common
second messengers
Fig !!-!!
http://bcs.whfreeman.com/thelifewire/content/chp15/15020.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp15/15020.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp15/15020.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp15/15020.html -
7/24/2019 ap bio power point ch. 11
25/37
+irst messenger
Fig !! !!
G protein
denylyl
cyclase
GTP
TP
c0PSecondmessenger
Protein5inase
G protein-coupled
receptor
Cellular responses
-
7/24/2019 ap bio power point ch. 11
26/37
Response: Cell signaling leads to regulation oftranscription or c#toplasmic activities
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
-
7/24/2019 ap bio power point ch. 11
27/37
$uclear and C#toplasmic Responses
/ltimately, a signal transduction pathway leadsto regulation of one or more cellular activities
regulation of a cytosolic en0yme
! @r
7egulation of a gene
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig !!-!#
-
7/24/2019 ap bio power point ch. 11
28/37
g
&eception
Transduction
&esponse
$inding o epinephrine to G protein-coupled receptor (' molecule)
,nactive G protein
ctive G protein ('61molecules)
,nactive adenylyl cyclase
ctive adenylyl cyclase ('61)
TP
Cyclic 0P ('64)
,nactive protein 5inase
ctive protein 5inase ('64)
,nactive phosphorylase 5inase
ctive phosphorylase 5inase ('67)
,nactive glycogen phosphorylase
ctive glycogen phosphorylase ('68)
Glycogen
Glucose-'-phosphate
('69
molecules)
-
7/24/2019 ap bio power point ch. 11
29/37
%ine-Tuning of the Response
5ultistep pathways have two importantbenefits$
Amplifying the signal 3and thus the response4
! At each step, the number of activatedproducts is much greater than in the
preceding step
Contributing to the specificity of the response! ;ach step is specific- remember the
specificity of each en0yme for its substrate
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
-
7/24/2019 ap bio power point ch. 11
30/37
The Specificity of Cell Signaling and Coordinationof the Response
ifferent 8inds of cells have different collections ofproteins
ifferent A e+pressed in different types of
cells
2hese different proteins allow cells to detect and
respond to different signals
;ven the same signal can have different effects incells with different proteins and pathways
athway branching and >cross-tal8? further help
the cell coordinate incoming signalsCopyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
-
7/24/2019 ap bio power point ch. 11
31/37
Signaling Efficiency: Scaffolding Proteins andSignaling Complexes
Scaolding proteins are large relay proteinsto which other relay proteins are attached
:caffolding proteins can increase the signal
transduction efficiency by grouping togetherdifferent proteins involved in the same pathway
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig !!-!
-
7/24/2019 ap bio power point ch. 11
32/37
Signalingmolecule
&eceptor
Scaoldingprotein
Plasmamembrane
Threedierentprotein
5inases
-
7/24/2019 ap bio power point ch. 11
33/37
Termination of the Signal
Inactivation mechanisms are an essentialaspect of cell signaling
Bhen signal molecules leave the receptor, the
receptor reverts to its inactive state
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
A t i d ll d th
-
7/24/2019 ap bio power point ch. 11
34/37
Apoptosis- programmed cell death
-
7/24/2019 ap bio power point ch. 11
35/37
Apoptosis &programmed cell death' integratesmultiple cell-signaling path(a#s
poptosis is programmed or controlled cellsuicide
A cell is chopped and pac8aged into vesicles
that are digested by scavenger cells
Apoptosis prevents en0ymes from lea8ing out
of a dying cell and damaging neighboring cells
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig !!-!
-
7/24/2019 ap bio power point ch. 11
36/37
1 :m
;+tracellular signals result in formation of blebs
-
7/24/2019 ap bio power point ch. 11
37/37
Apoptotic ath(a#s and the Signals That TriggerThem
Apoptosis can be triggered by$ An e+tracellular death-signaling ligand
A damage in the nucleus
rotein misfolding in the endoplasmicreticulum
Apoptosis may be involved in some diseases
3for e+ample, ar8insons and Al0heimers4Dinterference with apoptosis may contribute to
some cancers