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Cell

Membranes

&

Movement Across Them

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Membran Sel

Memisahkan sel dari lingkungannya

Membran sel adalah perbatasan

Masukmakanan

- gula

- protein- lemak

garam

O2H2O

KeluarZat sisa

- ammonia

- garam- CO2- H2O

hasil

- protein

sel membutuhkan materi yang masuk & hasil atau zat sisa

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Membangun a membran

How do you build a barrier that keepsthe watery contents of the cell separate

from the watery environment?

What substance

do you know

that doesnt mix

with water?

FATSLIPIDS

Remember:oil & water

dont mix!!

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Lemak dari membran sel

Membran terbuat dari jenis spesial lemak phospholipids

kepribadian ganda

Membrane adalah lapisan ganda

phospholipid bilayer

Sel masuk

Sel keluar

lipid

Ditolak air

Tertarik air

phosphate

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Membran Semi-permeable

Membran sel mengontrol apa yang masukdan keluar

Perlu memperbolehkan beberapamaterialtapi tidak semuauntukmelewati membran

semi-permeable only some material can get in or out

aa H2Osugar lipids salt wasteO2

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Menyebrangi membran sel

Apa molekul yang dapat melalui membransel secara langsung?

Lemak dan minyak dapat melalui secara

langsung

Sel masuk

Sel keluar

lemakgaram

aa H2Ogula

waste

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Saluran membran sel

Perlu membuat pintu untuk dilalui Saluran protein memperbolehkan zat-zat masuk dan keluar

Saluran khusus memperbolehkan bahan-bahan masuk dan

keluar

Saluran H2O, asaluran garam, saluran gula, danlain-lain

Sel masuk

Sel keluar

gulaaaH2O

garamsisa

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Saluran terbuat dari protein

proteins keduanya menyukai air dan lemak

bi-lipidmembrane

protein channelsin bi-lipid membrane

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Saluran Protein

Proteins sebagai pintu masuk membran Saluran untuk memindahkan molekul

tertentu melalui membran

HIGH

LOW

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Movement through the channel

Why do molecules move throughmembrane if you give them a channel?

?

?

HIGH

LOW

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Molecules move from high to low

Diffusion move from HIGHto LOWconcentration

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Diffusion

Move from HIGHto LOWconcentration passive transport

no energy needed

diffusion osmosis

diffusion of water

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Simple Diffusion

Move from HIGHto LOW

inside cell

outside cell

Which way

will fat move?fat

fatfat

fat

fatfat fat

fatfat

fat

fatfat

fatfat

LOW

HIGH

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Facilitated Diffusion

Move from HIGHto LOW through a channel

inside cell

outside cell

sugar

sugarsugar

sugar

sugarsugar

sugar sugar

sugar sugarsugar

Which way will

sugar move?

sugarsugar

LOW

HIGH

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Diffusion

Move from HIGHto LOWconcentration directly through membrane

simple diffusion

no energy needed

help through a protein channel

facilitated diffusion(with help)

no energy needed HIGH

LOW

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Simple vs. facilitated diffusion

inside cell

outside cell

lipid inside cell

outside cell

H2O

simple diffusion facilitated diffusion

H2Oprotein channel

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Active transport

Cells may need molecules to moveagainst concentration hill

need to pump uphill

from LOWto HIGHusing energy

protein pump

requires energy

ATPATP

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Transport summary

simple

diffusion

facilitateddiffusion

active

transport

ATP

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Osmosis

Movement of Water AcrossCell Membrane

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Osmosis

Water is very important, so we talk aboutwater separately

Osmosis

diffusion of water from HIGH concentrationof water to LOW concentration of water

across a semi-permeable membrane

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Keeping water balance

Cell survival depends on balancingwater uptake & water loss

freshwater balanced saltwater

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Keeping right amount of water in cell

Freshwater a cell in fresh water

high concentration of wateraround cell

cell gains water example: Paramecium

problem: cells gain water,

swell & can burst

water continually enters

Parameciumcell

solution: contractile vacuole

pumps water out of cell

freshwater

No problem,here

KABOOM!

1

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Controlling water

Contractile vacuole in Paramecium

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Keeping right amount of water in cell

Saltwater a cell in salt water

low concentration of wateraround cell cell loses water

example: shellfish

problem: cell loses water

in plants: plasmolysis in animals: shrinking cell

solution: take up water

saltwater

I willsurvive!

Im shrinking,Im shrinking!

2

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Keeping right amount of water in cell

Balanced conditions no difference in

concentration of waterbetween cell & environment

cell in equilibrium

example:blood

problem: none

water flows acrossmembrane equally,in both directions

volume of cell doesntchange

balanced

I couldbe better

Thatsbetter!

3

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Ice Fishing in Barrow

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