Download - transport membrane (lengkap)
Pendahuluan
Transport Aktifb
Struktur dan Fungsi Membran Sel1
Transport Melalui Membran2
Transport Pasifa
Cotransportc
Exocytosis, Endocytosis & Transcytosisd
• Bagian terluar sel
• Membatasi bagian dalam dan lingk luar
• Sebagai reseptor (penerima) rangsang dari luar seperti hormon dan bahan kimia lain, baik dari lingk luar maupun dari dalam
• Melindungi isi sel agar tidak keluar
• Mengontrol zat yang keluar dan masuk
• Sebagai tempat terjadinya kegiatan biokimia (seperti reaksi oksidasi dan respirasi)
Fungsi Membran Sel
Struktur Membran Sel
Fosfolipid
• HYDROPHILIC heads (water liking)-Attracted to the water
• called POLAR
• HYDROPHOBIC tails (water fearing)-Not attracted to the water
• called NON-POLAR
Struktur Membran SelEffect of temperature on the packing of the
hydrocarbons
• Low temperatures the bilayer is in a gel state and tightly packed.
• At higher (body) temperatures the bilayer actually "melts' and the interior is fluid allowing the lipid molecules to move around, rotate, exchange places. This also allows movement of other components of the membrane.
Struktur Membran SelStruktur Membran Sel
Cholesterol • Another type of lipid in the membrane
is cholesterol. The amount of cholesterol may vary with the type of membrane. Plasma membranes have nearly one cholesterol per phospholipid molecule. Other membranes (like those around bacteria) have no cholesterol.
Struktur Membran Sel
Fungsi Cholesterol
1. They immobilize the first few hydrocarbon groups of the phospholipid molecules.
2. This makes the lipid bilayer less deformable and decreases its permeability to small water-soluble molecules. Without cholesterol (such as in a bacterium) a cell would need a cell wall.
3. Cholesterol prevents crystallization of hydrocarbons and phase shifts in the membrane.
Two major types of membrane proteins
• Look at the picture and notice the integral proteins and the peripheral proteins.
Struktur Membran Sel
PROTEIN
Transmembrane or embedded proteins allowing for passage through the membranes hydrophobic region
Struktur Membran Sel
INTEGRAL PROTEIN
PERIFERAL PROTEIN
• Appendages to the membrane or may be found attached to integral proteins
Transport proteins
• Usually integral
• Specific for solute
• Some hydrolyze ATP
Struktur Membran Sel
LALU LINTAS MATERIKELUAR MASUK SEL
1. Prinsip
a. Ada pergerakan materi keluar masuk
sel.
b. Nutrisi harus masuk.
c. Sampah harus keluar.
d. Ion bergerak keluar masuk.
2. Mekanisme
a. Transpor pasif
- Difusi
Pergerakan partikel/molekul/ion terlarut dari tempat yang konsentrasinya tinggi ke tempat yang konsentrasinya lebih rendah.
- Osmosis
Pergerakan cairan pelarut melalui membran semipermeabel dari tempat yang konsentrasinya lebih rendah, ke tempat yang konsentrasinya lebih tinggi.
b. Transpor aktifPergerakan molekul/ion melawan gradien konsentrasinya dengan menggunakan energi yang dihasilkan sel itu sendiri.Mis : Pompa Natrium
Pompa CalsiumEndo/Eksositosis
LALU LINTAS MATERI KELUAR MASUK SEL
1. Oxygen – Non-polar so diffuses very quickly.
1. Carbon dioxide – Polar but very small so diffuses quickly.
2. Water – Polar but also very small so diffuses quickly.
TRANSPORT PASIF
Zat-zat yang berdifusi
1. Gradien konsentrasi zat
2.Temperature.
3.Luas area permukaan/ ukuran molekul
4.Tipe molekul atau ion yang berdifusi
TRANSPORT PASIF
Faktor-faktor yang mempengaruhi
kecepatan difusi
• Large polar molecules such as glucose and amino acids, cannot diffuse across the phospholipid bilayer. Also ions such as Na+ or Cl- cannot pass.
• These molecules pass through protein channels instead. Diffusion through these channels is called FACILITATED DIFFUSION.
• Movement of molecules is still PASSIVE just like ordinary diffusion, the only difference is, the molecules go through a protein channel instead of passing between the phospholipids.
TRANSPORT PASIF
Difusi terfasilitasi
Cell membrane
Inside cell Outside cell
Protein channel
diffusion
TRANSPORT PASIF
Difusi Terfasilitasi
Cell membrane
Inside cell Outside cell
Protein channel
diffusion
EQUILIBRIUM
TRANSPORT PASIF
Difusi Terfasilitasi
• The cells of organisms
are surrounded by and
filled with fluids that are
made mostly of water.
• The movement of
(diffusion) of water
through cell membranes
is so important to life
processes that it has
been given a special
name- OSMOSIS
TRANSPORT PASIF
Osmosis
• Osmosis : gerakan air dari potensial air lebih tinggi ke potensial air lebih rendah melewati membran selektif permeabel sampai dicapai keseimbangan dinamis
TRANSPORT PASIF
Osmosis
Cell membrane
partially
permeable.
Inside cell Outside cellVERY High conc.
of water
molecules. High
water potential.
VERY Low conc.
of water
molecules. High
water potential.
Sugar molecule
DILUTE SOLUTIONCONCENTRATED SOLUTION
TRANSPORT PASIF
Osmosis
Cell membrane
partially
permeable.
Inside cell Outside cellHigh conc. of
water molecules.
High water
potential.
Low conc. of
water molecules.
High water
potential.OSMOSIS
TRANSPORT PASIF
Osmosis
Cell membrane
partially
permeable.
Inside cell Outside cell
OSMOSIS
EQUILIBRIUM. Equal water concentration on each side.
Equal water potential has been reached. There is no net
movement of water
TRANSPORT PASIF
Osmosis
• Osmosis important to cellular functions.
• RBC (red blood cells) are swimming in plasma which is mostly water with salts, sugars, and other nutrients.
TRANSPORT PASIF
The cell & Osmosis
• Isotonic – solutions with the same solute concentration as that of the cytosol
• Hypertonic – solutions having greater solute concentration than that of the cytosol; water leaves the cell causing crenation(shrinkage)
• Hypotonic – solutions having lesser solute concentration than that of the cytosol; water enters the cell causing swelling and potential lysis
TRANSPORT PASIF
Effect of Water on RBC
Tonicity – how a solution’s osmolarity affects cell volume
Types of Active Transport
Primary active transport:
hydrolysis of ATP
phosphorylates the transport
protein causing conformational
change
Secondary active transport:
use of an exchange pump
(such as the Na+-K+ pump)
indirectly to drive the transport
of other solutes
Symport system – two
substances move across a
membrane in the same
direction (also called
cotransport)
Antiport system – two
substances move across a
membrane in opposite
directions (also called
countertransport)
TRANSPORT AKTIFTIPE
Active Transport Active transport - movement of materials
AGAINST the concentration gradient from low concentration to high concentration
Requires the cell to use energy (ATP)
2 kinds:
1. membrane pumps
2. vesicle transports
Active Transport
• Active transport proteins:
– Move substrates against concentration gradient
– Require energy, such as ATP
– Ion pumps move ions (Na+, K+, Ca+, Mg2+)
– Na+-K+ Exchange Pump moves both of these ions at the
same time, each in the opposite direction (called antiport or
countertransport)
– Proton Pump uses photosynthesis or food energy to create
a proton concentration gradient that then is used to
manufacture ATP
Sodium-Potassium Exchange Pump
Active transport, carrier mediated:
1 ATP moves 3 Na+ out 2 K+ in
This creates an electrical potential across the membrane
Called the Transmembrane Potential
Transmembrane Potential• Voltage across a membrane
• Resting membrane potential –the point where K+ potential is balanced by the membrane potential
– Ranges from –20 to –200 mV
– Results from Na+ and K+
concentration gradients across the membrane
– Differential permeability of the plasma membrane to Na+
and K+
• Steady state potential is maintained by active transport of ions
– Expends metabolic energy to
pump protons across membranes
Proton Pump (in Mitochondrial Membranes)
Proton PumpPLAY
Vesicular Transport
• Also called bulk transport
• Transport of large particles and macromolecules across plasma
membranes
Directional Descriptive Terms
– Exocytosis – moves substance from the cell interior to the extracellular
space
– Endocytosis – enables large particles and macromolecules to enter the
cell
• Receptor-mediated
• Pinocytosis
• Phagocytosis
Functional Descriptive Terms
– Transcytosis – moving substances into, across, and then out of a cell
– Vesicular trafficking – moving substances from one area in the cell to
another
– Phagocytosis – pseudopodsengulfsolidsandbringthemintothecell’s
interior
Receptor-Mediated Endocytosis
• Receptors (glycoproteins called clathrin) bind target
molecules (ligands)
• Coated vesicle (endosome) carries ligands and
receptors into the cell
• Phagocytosis (cell eating)
– pseudopodia (psuedo = false,
podia = feet)
– engulf large objects in
phagosomes