PPT BIOFISIKA

By : SITI QOMARIYAH SITI AMINAH TINA SEPTIKASARI

TRANSPORT PHENOMENON

OUTLINE

STRUKTUR SEL

TRANSPORT MEMBRAN

GO

GO

STRUKTUR SEL

APA ITU SEL ??

Sel adalah unit terkecil dari makhluk hidup yang membentuk struktur dan fungsi tertentu.

o STRUKTUR UMUM SEL

SEL

BAGIAN LUAR SEL

(MEMBRAN DAN DINDING SEL)

SITOPLASMA

NUKLEUS/ INTI SEL

BAGIAN DALAM SEL

(SITOPLASMA DAN ORGANEL)

ORGANEL LAIN

BAGIAN- BAGIAN SEL

BAGIAN- BAGIAN SEL

TRANSPOR PASIF(Transpor tanpa menggunakan energi)

TRANSPOR AKTIF(Transpor dengan menggunakan energi) karena dari konsentrasi rendah tinggi

TRANSPORT PADA MEMBRAN

DIFUSI OSMOSIS

Sederhana

TerfasilitasiDibantu dengan

protein pembawa di membran

palsma sehingga membentuk kanal

dan molekul bergerak melintasi

membran

Difusi molekul air melintasi membran permeabel

Endositosis Eksositosis

“memakan”(fagositosis)

“memuntahkan”

“meminum”(pinositosis)

20

07

-20

08

Sistem transport yang

terjadi pada sel berlangsung

melalui membran sel..

Extracellular fluid

Cholesterol

Cytoplasm

Glycolipid

Transmembraneproteins

Filaments ofcytoskeleton

Peripheralprotein

Glycoprotein

Phospholipids

GO TO OUTLINE

BAGIAN – BAGIAN MEMBRAN SEL :

Difusi Sederhana Mekanisme Difusi Sederhana :

DIFUSI: pergerakan molekul dari konsentrasi

tinggi rendah

DIFUSI: pergerakan molekul dari konsentrasi

tinggi rendah

o DIFUSI TERFASILITASI (TERBANTU)

Diffusion through protein channelschannels move specific molecules across

cell membraneno energy needed

“The Bouncer”“The Bouncer”

open channel = fast transport

facilitated = with help

high

low

Diffusion

Mass flow process by which species change their position relative to their neighbours

Driven by thermal energy and a gradient

Thermal energy → thermal vibrations → Atomic jumps

Concentration / chemical potential

ElectricGradient

Magnetic

Stress

HUKUM FICK’S

Assume that only B is moving into A

Assume steady state conditions → J f(x,t) (No accumulation of matter)

Flux (J) (restricted definition) → Flow / area / time [Atoms / m2 / s]

Fick’s I law

dx

dcDA

dt

dn

No. of atoms crossing area A

per unit time

Cross-sectional area

Concentration gradient

Matter transport is down the concentration gradient

Diffusion coefficient/ diffusivity

AFlow direction

As a first approximation assume D f(t)

dx

dcDA

dt

dn

gradientionconcentrattimeareaatomsJ //

dx

dcJ

dx

dcDJ

dx

dcD

dt

dn

AJ

1

Fick’s first law

Diffusivity (D) → f(A, B, T)

D = f(c)

D f(c)C1

C2

Steady state diffusion

x →

Con

cent

rati

on →

Diffusion

Steady state J f(x,t)

Non-steady stateJ = f(x,t)

D = f(c)

D = f(c)

D f(c)

D f(c)

Fick’s II law

Jx Jx+x

xxxx JJonAccumulati

xx

JJJonAccumulati xx

xx

JJJx

t

cxx

Jsm

Atomsm

sm

Atoms

23.

1

xx

Jx

t

c

x

cD

xt

cFick’s first law

x

cD

xt

c D f(x)2

2

x

cD

t

c

2

2

x

cD

t

c

RHS is the curvature of the c vs x curve

x →

c →

x →c

→

+ve curvature c ↑ as t ↑ ve curvature c ↓ as t ↑

LHS is the change is concentration with time

2

2

x

cD

t

c

Dt

xerfBAtxc

2 ),(

Solution to 2o de with 2 constantsdetermined from Boundary Conditions and Initial Condition

0

2exp2

duuErf

Erf () = 1 Erf (-) = -1 Erf (0) = 0 Erf (-x) = -Erf (x)

u →

Exp

( u

2 ) →

0

Area

A B

Applications based on Fick’s II law

x →

Con

cent

rati

on →

Cavg

↑ t

t1 > 0 | c(x,t1)t2 > t1 | c(x,t1) t = 0 | c(x,0)

A & B welded together and heated to high temperature (kept constant → T0)

Flux

f(x)|t

f(t)|x

Non-steadystate

If D = f(c) c(+x,t) c(-x,t)

i.e. asymmetry about y-axis

C(+x, 0) = C1

C(x, 0) = C2

C1

C2

A = (C1 + C2)/2

B = (C2 – C1)/2

Determination of Diffusivity

kT

Q

eDD 0

Temperature dependence of diffusivity

Arrhenius type

Applications based on Fick’s II law Carburization of steel

Surface is often the most important part of the component, which is prone to degradation

Surface hardenting of steel components like gears is done by carburizingor nitriding

Pack carburizing → solid carbon powder used as C source

Gas carburizing → Methane gas CH4 (g) → 2H2 (g) + C (diffuses into steel)

x → 0C1

CS

C(+x, 0) = C1

C(0, t) = CS

A = CS

B = CS – C1

Approximate formula for depth of penetration

Dtx

OSMOSIS