PPT BIOFISIKA
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Transcript of PPT BIOFISIKA
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
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)
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
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
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