01 - membranes, energy

7/18/2019 01 - Membranes, Energy

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Lecture 1 Outline (Ch. 5)

I. Membrane Structure

II. Permeability

III. Transport Across Membranes

A. Passie

!. "acilitate#

C. Actie

$. !ul%



Membrane structure

1915, knew membrane made of lipids and proteins

• Reasoned that membrane = bilayer

Where to place proteins?

Lipid layer 1

Lipid layer 2

roteins



Membrane structure



• free!e fract"re

• proteins intact,

one layer or other

• two layers look different

Membrane structure



#$periment to determine membrane fl"idity%

• marked membrane proteins mi$ed in hybrid cell

Membrane structure



&embrane fl"idity

• phospholipid f'a' (tails)% sat"ration affects fl"idity

• cholesterol b"fferstemperat"re chan*es

Membrane structure



(fl"id mosaic model) + 19-s

• fl"id + phospholipids mo.e aro"nd

• mosaic + proteins embedded in membrane

Membrane structure



• cell membrane + amphipathic / hydrophilic 0 hydrophobic

• membrane proteins inserted, also amphipathic

Membrane structure

hydrophilic

hydrophilic

hydrophobic



Membrane Proteins

&embrane proteins%

/ transmembrane + span

membrane

nte*ral% inserted in membrane

eripheral% ne$t to membrane

/ inside or o"tside



• wo transmembrane proteins% different str"ct"re

3acteriorhodopsin% proton p"mp

Membrane structure

3acterial pore protein



Membrane Proteins



Moement o& molecules

4imple iff"sion% most basic

force to mo.e molec"les

• isperse "ntil concentration e6"al in all areas



• 4mall, non/polar molec"les 78

e$' steroids, 72, 72

Moement o& molecules

ell membranes only allow some molec"les across w:o"t help%

• ;o char*ed, polar, or lar*e molec"les

e$' s"*ars, ions, water<



Transport Across Membranes

ypes of transport%

' assi.e transport

/ 4imple diff"sion

/ >acilitated diff"sion

/ 7smosis

3' cti.e transport

' 3"lk transport

• #ner*y Re6"ired?

• irectionality?



• 7W; concentration *radient

• molec"lese6"ally distrib"te

across a.ailable

area by type

Passie Transport ' Simple $i&&usion

/ non/polar molec"les

steroids, 72, 72@

• ;7 #;#RAB re6"ired



• 7W; concentration *radient

• molec"les e6"ally distrib"te b"t cross membrane

with the help of a channel a@ or carrier b@ protein'

Passie Transport "acilitate# $i&&usion

• ;7 #;#RAB re6"ired



• osmosis + mo.ement

of water across cell

membrane

• water crosses cell

membranes .iaspecial channels

called a6"aporins

Passie Transport ' Osmosis

• mo.es into:o"t of cell "ntil

solute concentration is balanced




e6"al sol"tes in

sol"tion as in cell

more sol"tes in

sol"tion, than in cell

fewer sol"tes in

sol"tion, than in cell

n each sit"ation below, does water ha.e net

mo.ement, and which direction%



• tonicity + C sol"tes in sol"tion in relation to cell

/ isotonic + e6"al

sol"tes in sol"tion

/ hypertonic + more

sol"tes in sol"tion

animal cell

plant cell

/ hypotonic + fewer

sol"tes in sol"tion




Paramecium e$ample

• re*"late water balance

• water into contractile

.ac"ole + water

e$pelled

• pond water hypotonic




4cenario% in mo.ie theater, watchin* a long mo.ie'

Bo" are% drinkin* water

Bo" are% eatin* popcorn

What happens to yo"r

blood?

What happens to yo"r

blood?




• transport proteins

a' ion p"mps"niporters@

• #$' ;a/8 ion p"mp

/ ;aD ions% inside to o"t

b' symporter:antiporter

/ 8D ions% o"tside to in

Actie Transport

• E:A;4concentration *radient

• #;#RAB 4 re6"ired

• antiporter% two molec"les mo.e

opposite directions E *radient@

c' co"pled transport



• "sed p"mp FD ions o"t

<*radients + "sed by cell for ener*y potential

• a*ainst concentration and char*e *radients

Actie Transport ' uniporter

• #$' proton FD@ p"mp

• "niporter%

7;# molec"le

E *radient



Actie Transport couple# transport

• #$' cti.e *l"cose transporter

• ;aD diff"sion "sed for

*l"cose acti.e transport

• ;aD mo.in* 7W;

concentration *radient

• Al"cose mo.in* E

concentration *radient

• co"pled transport% one molec"le

E *radient 0 other 7W;

*radient opposite directions@



• pha*ocytosis

+ (food) in

• pinocytosis

+ water in

• &olec"les mo.ed ; / endocytosis

!ul% Transport

• #;#RAB 4 re6"ired

• 4e.eral or lar*e molec"les



!ul% Transport

• receptor/mediated endocytosis

+ proteins bind molec"les, .esicles inside

• &olec"les

mo.ed 7E

/

e$ocytosis



Sel&'Chec%

Type o&transport

ner*yre+uire#,

Moement#irection,

-amples

4imple diff"sion no own conc' *radient 72, 72, non/

polar molec"les

7smosis

>acilitateddiff"sion

cti.e transport

3"lk transport



L t 1 O tli (Ch /)



Lecture 1 Outline (Ch. /)

I. ner*y an# Metabolism

II. Thermo#ynamics

A. 1st La0 conseration o& ener*y

!. n# La0 ' entropy

III. "ree ner*y

I2. Chemical 3eactions

2. Cellular ner*y ' ATP

2I. n4ymes

A. "unction

!. 3e*ulation

#



What is #ner*y?

he capacity to

ca"se chan*e

#ner*y

Where does ener*y on earth come from ori*inally?

G- million billion calories per secondH

& t b li



&etabolism

&etabolism +chemical con.ersions in an organism

ypes of #ner*y%

/ 8inetic #ner*y = ener*y of mo.ement / thermal

/ otential = stored ener*y / chemical

hermodynamics



otential ener*y can be con.erted to kinetic ener*y 0 .ice .ersa@

otential #ner*y 8inetic #ner*y

hermodynamics

hermodynamics + st"dy of ener*y transformation in a system

hermodynamics



Laws of hermodynamicsLaws of hermodynamics%% #$plain the characteristics of ener*y

1st

Law%• #ner*y is conser.ed

• #ner*y is not created or destroyed

• #ner*y can be con.erted hemical → Feat@

2nd Law%

• "rin* con.ersions, amo"nt of "sef"l ener*y decreases

• ;o process is 1--I efficient

hermodynamics

#ner*y is con.erted from more useful to less useful forms

• #ntropy meas"re of disorder@ is increased

&etabolism



&etabolic reactions% hemical reactions in or*anism

nabolic = b"ilds

"p molec"les

&etabolism

wo ypes of Metabolic Reactions%

atabolic = breaks

down molec"les

hemical Reactions



hemical Reactions%

• Like home offices + tend toward disorder

hemical Reactions

hemical Reactions



hemical Reactions%

• #nder*onic + ener*y re6"ired to complete reaction

• #$er*onic + ener*y *i.en off

#$er*onic

#nder*onic

hemical Reactions

hemical Reactions



hemical Reaction%

• rocess that makes and breaks chemical bonds

D

Reactants

D

rod"cts

wo ypes of Chemical Reactions%1@ #$er*onic = releases ener*y

2@ #nder*onic = re6"ires ener*y

hemical Reactions

hemical Reactions



. Endergonic reactions (#ner*y in)

•rod"cts ha.e more ener*y than reactants

•Re6"ires infl"$ of ener*y

1. Exergonic reactions (#ner*y o"t)

• Reactants ha.e more ener*y than prod"cts• Reaction releases ener*y

hemical Reactions

hemical Reactions



hemical Reactions

• #$er*onic reaction • #nder*onic reaction

release free ener*yspontaneo"s

intake free ener*ynon/spontaneo"s

Al"cose 72 D F2- 72 D F2- Al"cose

hemical Reactions



cti.ation #ner*y% #ner*y re6"ired to (J"mpstart) a chemical

reaction

• &"st o.ercome rep"lsion of molec"les d"e to ne*ati.echar*ed electrons

;"cle"s Repel ;"cle"s

;"cle"sRepel

;"cle"s

cti.ation#ner*y

cti.ation#ner*y

hemical Reactions

hemical Reactions



-er*onic 3eaction + Reactants ha.e more ener*y than products

But will sugar spontaneously burst into flames? cti.ation ener*y%

&ake s"*ar and 72

molec"les collide

hemical Reactions

(ownhill) reactions

su*ar O

0ater CO

ell"lar #ner*y



ell"lar #ner*y /

• = adenosine

triphosphate

• ribose, adenine, K phosphates

• last terminal@ phosphate/ remo.able

ell"lar #ner*y



• hydroly!ed to

D F27 D i

• #ner*y released, co"pled to another chemical reaction

ell"lar #ner*y /

• stores 'K calories per mole

ell"lar #ner*y



• re*enerated

• need 'K kcal:mol to b"ild

• cells power b"ildin* by co"plin* to e$er*onic reactions

/ cell"lar respiration

ell"lar #ner*y /

#n!ymes



#n!ymes

#ner*y of acti.ation # @

• reactants + absorb ener*ycalled% #

• Reach # , reaction

proceeds limitin* step@

#$er*onic + ener*y *i.en off

• # from ambient heat "s"ally ins"fficient

• his is A77H

#n!ymes



#n!ymes

#n!ymes

• lower #

• only for specific r$ns

• cell chooses which

reactions *o forwardH

en!ymes%

/do speed "p r$n wo"ld occ"r anyway

/do not make ender*onic e$er*onic

#n!ymes



#n!ymes

• en!yme + specific to s"bstrate

• acti.e site + part of en!yme /s"bstrate

• bindin* ti*htens fit + ind"ced fit

• form en!yme/s"bstrate comple$

• catalytic part of en!yme%

con.erts reactants@ to prod"cts@

#n!ymes



#n!ymes

#n!ymes



#n!ymes

• s"bstrates@ enter

• #n!ymes lowers # by%

• prod"cts formed

/template orientation

/stress bonds

/microen.ironment

• en!yme re"sed

6 7hat &actors mi*ht a&&ect en4yme actiity,

#n!ymes



#n!ymes

• inhibitors%

• r"* + blocks F en!ymeat the acti.e site

#n!ymes

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>eedback nhibition%

y

Like yo"r f"rnace%

etector

warm

room

>"rnace

t"rns on

Room is

warm

cold

room

Lect"re 1 4"mmary



Lect"re 1 4"mmary1' &embrane composition and f"nction h' 5@

/ hospholipids and cholesterol

/ nte*ral and peripheral proteins

2' Fow molec"les cross membranes h' 5@

/ assi.e ransport

/ cti.e ransport

/ 3"lk ransport

K' #ner*y h' M@/ ypes, con.ersion

G' &etabolic:chemical reactions h' M@

/ atabolic:#nder*onic

/ nabolic:#$er*onic5' h' M@

M' #n!ymes h' M@

/ "rpose

/ >"nction

01 - membranes, energy

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