MU AN3 [Recovered]

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MU AN3 [Recovered]

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STRUKTUR SEL DAN FUNGSINYA

STRUKTUR SEL DAN FUNGSINYA5 Maret 2015SELUnit struktur dasar dari organisme hidup

Masing-masing sel dibatasi oleh membran sitoplasma

Faktor keturunan dalam sel molekul DNA

Berbagai reaksi enzimatis untuk membentuk energi atau mensistesa sel baru

Berdasar struktur prokariotik dan eukariotik

Membran SitoplasmaSel hidup Pertukaran material dengan lingkungan sekitar

Fungsi : mengatur aliran material dari dalam ke luar sel atau sebaliknya

Barrier yang permiable dengan selektivitas yang tinggi

Molekul kecil, molekul netral mudah melewati membran

Molekul besar atau melekul kecil yang bermuatan tidak dengan bebas melewati menran melalui sistem transport tertentu

Kalau membran sitoplasma rusak integritas sel rusak isi sel keluar

Terdapat perbedaan antara MS pada sel bakteri, archea dan eukariotik dalam :a. Kandungan proteinb. Komposisi lemakc. Struktur lemakd. Ikatan lemake. Ada/tidaknya sterol

MS bakteri

Fosfilipid, bersifat amfifilik fosfat (hidrofilik) & asam lemak (hidrofobik), yang diikat oleh gliserol fosfolipid bilayer Fungsi protein pada MSFunctionLocation in membraneExampleEnergy transformationInside surfaceATP-ase F1Transport of moleculesInside surfaceHPrProtein exportInside surfaceDocking proteinAssociation of DNA with membraneInside surfaceDNA-binding proteinTransport of moleculesBoth sidesPermeaseChemotaxisBoth sidesMethyl-accepting chemotaxis proteinsElectron & proton transportBoth sidesFlavoproteinsPenicillin-binding proteinsOutside surfaceCell wal biosynthesisFlagellar activityOutside surfaceM protein of basal body of flagellumMS pada eukariotikMirip bakteri ada fosfolipid, proteinAda sterolMenyusun 25% lipid MSSebagai target antibiotik pencegah infeksi fungiVariasi sterol pada tiap spesiesManusia & hewan terbanyak kolesterolFungi ergosterolSISTEM TRANSPORTTidak membutuhkan energi :- Difusi pasif- Osmosis (air)- Difusi dengan fasilitator (perantara) proteinMembutuhkan energi- Transport aktif- Protonmotive force- Pompa sodium potasium- Translokasi gugus- Binding protein transport- Cytosis

Difusi pasifPerpindahan molekul dari konsentrasi solut tinggi ke rendah molekul kecil mudah molekul besar (gula & as amino) sulit (V = 1/10.000 air)

Tanpa bantuan Penentu kecepatan difusi: beda konsentrasi permeabilitas MS

OsmosisPerpindahan air melalui membran yang disebabkan oleh perbedaan konsentrasi larutanPada umumnya perpindahan air berlangsung ke dalam sel karena konsemtraso larutan di dalam sel lebih tinggi

Akibat yang mungkin terjadia. normal cell (kondisi isotonik)b. shrunken cell (kondisi hipertonik) plasmolisc. bursting cell (kondisi hipotonik) osmotik shock

Difusi dengan fasilitator proteinDitujukan untuk meningkatkan kecepatan perpindahan komponen yang permiabel lewat protein transmembranPerpindahan molekul dari konsentrasi solut tinggi ke rendah, lebih cepat biasanya pada sel eukariotikbakteri transpor gliserolProtein dalam MSPembawa molekul (multiple atau tunggal)

Transport aktifMembrane transport requiring the expendicture of cellular energy and in which the substance is not chemically modified as it is transported across the membrane.

PERMEASE trans membrane protein within the cytoplasmic membrane as carieers to move substances across the membrane. the movement of the substrat across the cytoplasmic membrane is driven by energy from ATP or ion gradient

Transport across the cytoplasmic membraneUniport the movement of single substanceContrasport movement of two substancesa. Symport in the same directionb. Antiport in the opposite direction

The energy for active transport in bacterial, archaeal, and algal cells

The protonmotive force is the energy that comes from separation of proton (hidrogen ions, H+) across the cytoplasmic membrane

The metabolism of bacterial cells is used to translocate proton out of cells proton out of cells > inside the cells movement of proton or aother cations back to the cells.

Protonmotive Force

In many eukaryotic cells a gradient between sodim ions (Na+) and potassiun ions (K+) is established and is analogous to the protonmotive force.

Na+ is pumped out of the cell and K+ is pumped into the cell by the enzyme Na+ K+ ATPase via the Sodium-Potassium Pump

Every three Na+ are pumped out, only two K+ are pumped in Na+ outside the cell ,K+ in the cell , unequal of + charge a powerful electrochemical gradient

Sodium-Potassium Pump

The transport process called group translocation that occurs in the PEP:PTS

the transported substance is chemically altered during passage through the membrane by the addition of phosphate.

Molecules transported via group translocation into bacterial cells include carbohydrates, fatty acid, and some of building blocks of nucleic acid

The PEP:PTS is found only in cells of some bacteria and does not occur in eukaryotic cells.

Group Translocation Phosphoenolpyruvate: Phosphotransferase system

Group Translocation Phosphoenolpyruvate: Phosphotransferase system

Specialized transport system that occurs only in gram-negative bacteria.

It involves a complex of protein associated with a second membrane, called the outer membrane, that surrounds gram-negative bacterial cells

Acts as a shuttle, carrying the maltose from the outer membrane to the next protein.

Binding Protein Transport

Some substances enter and leave eukaryotic cells by cytosis, a transport process in wich a substance is engulfed by the cytoplasmic membrane to form a vesicle.

Endocytosis movement of material into the cellsExocytosis movement of material out of the cells

Phagocytosis one cells engulfs a smaller cells or particle.Ex. In protozoa (amoeba) that feed on bacteria, in human or animal cells enguls an digest bacteria as part of the imune response

Pinocytosis cells engulfs a fluid containing dissolved substances.

Cytosis

A. CytocisB. Phagocytocis

DINDING SELFungsi :Melindungi sel dari lingkungan yang tidak sesuai Menentukan bentuk sel prokariotRigiditas selPermukaan dinding sel berpori-pori : komponen biokimia dapat lewat dan mencegah masuknya molekul besar

Tipe struktur dinding sel1. gram positif 2. gram negatif

34Staphylococcus aureusEscherichia coli

StepGram +organismsGram -organisms1. Unstained2. Crystal Violet3. Iodine5. Safranin4. DecolorizationPerbedaan Gram+ from Gram -

PeptidoglikanLapisan rigid yang bertanggungjawab pada kekokohan sel

Gram positif

Gram Negative Outer Membrane

Porins - proteins that allow small molecules to cross membrane -- specific and non-specific

Protoplast Formation

High solute solutionLow solute solutionLysozyme -- a protein that breaks 1,4-glycosidic bonds in peptidoglycan