membran dan transport zat2011

Evi Umayah Ulfa, M.Si., Apt

KULIAH BIOLOGI DASAR

Komponen Penyusun Kimia Sel,

Membran dan Transport Zat

Komponen Kimia Sel

Organik

• Gula (HA)

• Lemak

• Protein

• Nukleotida

Anorganik

• Air

• Gas : O2,N2

• Mineral : P, O, K, S, Ca, Fe, Mg, Na, Cl, Cu, Mn, Zn, dan Mo

ASAM LEMAK

Asam Amino

Protein

Evi Umayah Ulfa, M.Si., Apt

MEMBRAN SEL

Membrane Cell

Membran plasma

Membran dalam

(Internal Membrane)

Component of membrane

• Lipid

– Amfifatik

• Hidrofob : asam lemak

(jenuh, tidak jenuh)

• Hidrofil : fosfat

– Molekul penyusun lipid

membran:

• Fosfolipid

• Kolesterol

• Glikolipid

• Protein

Membrane Lipids

Characteristic of Membrane

• Membrane Lipids Are Amphipathic

Molecules

• The Lipid Bilayer Is a Two-dimensional

Fluid

The degree of bilayer fluidity depends on the

lipid composition, structure of the

phospholipid hydrophobic tails, and

temperature

• The Lipid Bilayer Is Asymmetrical

Fluiditas Membran Sel

Protein pada

Membran

• Sel yang berbeda memiliki

membran protein yang berbeda

pula

• Berbagai membran di dalam sel

memiliki kumpulan protein yang

unik

• Proteins : fusngsi spesifik pada

membran

• Tipe protein pada membran :

• Integral MP/Transmembrane

• Lipid anchored MP

• Peripheral MP

Fungsi protein pada membran

Membran fosfolipid

IMPERMEABEL ( ion,

molekul besar tidak

bermuatan, molekul

yang bermuatan)

TRANSPOR ZAT

Transpor Pasif dan Aktif

Transpor Pasif

• Difusi

– Lemak, gas permiabel

• Difusi terfasilitasi

– Dibantu oleh transporter, Channel

• Osmosis

– Difusi air

Difusi

• Perpindahan Solut Tinggi ke Rendah

• Tidak memerlukan energi

• Berhenti jika telah setimbang

Difusi Pasif

Difusi Terfasilitasi

• Two major classes of membrane transport

proteins:

– carrier proteins (carriers, permeases, or

transporters)

– channel proteins form hydrophilic pores that

extend across the lipid bilayer; when these

pores are open, they allow specific solutes

(usually inorganic ions of appropriate size and

charge) to pass through them and thereby cross

the membrane

Transporter and Channel

Transporter/Carier

Chanel Protein

Transporter

Osmosis

• Difusi air melalui

membran

semipermeabel

• Konsentrasi

Tinggi rendah

• Solut tidak

berpindah

(besar)

Transport Aktif

• Rendah Tinggi

• Butuh Energi

• Ada 3 tipe

– Pompa protein

– Endositosis

– Eksositosis

Pompa Protein

• Protein transpor

(transporter) yang

membutuhkan energi

supaya bisa bekerja

(berubah konformasi)

• Contoh :

– Pompa Na/ K

respon sistem syaraf

ATP

Simporter/Antiporter/Uniporter ????

Endositosis

• Masuknya molekul

ke dalam sel

melalui

vesikel/vakuola

• Perlu Energi

• Contoh :

fagositosis oleh sel

darah merah

phagocytosis

pinocytosis

receptor-mediated

endocytosis

fuse with

lysosome for

digestion

non-specific

process

triggered by

molecular

signal

Eksositosis

• Perpindahan keluar molekul besar dari sel

melalui vesikel/vakuola

• Perubahan sel butuh Energi

• Sekresi Hormon keluar sel

EFEK OSMOSIS BAGI

KEHIDUPAN SEL

Konsentrasi

• Hipertonis

– High solute; Low water

• Hipotonis

– Low solute; High water

• Isotonis

– Solut and Water equal

Hypotonic Solution

Result: Water moves from the solution to inside the

cell): Cell Swells and bursts open (cytolysis)!

Hypertonic Solution

Result: Water moves from inside the cell into the

solution: Cell shrinks (Plasmolysis)!

• OsmosisAnimations for

isotonic, hypertonic, and hypotonic

solutions

shrinks

Isotonic Solution

Result: Water moves equally in both directions and

the cell remains same size! (Dynamic Equilibrium)

What type of solution are these cells in?

A CB

Hypertonic Isotonic Hypotonic

How Organisms Deal with

Osmotic Pressure

•Bacteria and plants have cell walls that prevent them from

over-expanding. In plants the pressure exerted on the cell

wall is called tugor pressure.

•A protist like paramecium has contractile vacuoles that

collect water flowing in and pump it out to prevent them

from over-expanding.

•Salt water fish pump salt out of their specialized gills so

they do not dehydrate.

•Animal cells are bathed in blood. Kidneys keep the blood

isotonic by remove excess salt and water.