lect3-sist slpt sitoplasmik.ppt
TRANSCRIPT
Sistem selaput sitoplasmik (selaput interna)
• Diperlukan bagi sel berukuran besar utk mencukupi kebutuhan enzim utk kegiatan sel
• Merupakan invaginasi/evaginasi berulang2 selaput sel
• Membagi sitoplasma menjadi bbrp ruang (kompartemen) ruang & slpt pembatas = organel
• RE, bdn golgi, lisosom & mikrobodi 1 sistem
Endomembrane System
• Many membranes are interrelated directly through physical continuity or indirectly through transport vesicles
Endoplasmic reticulum
•Klp membran ganda yg bertumpuk2, tdpt diantara membran sel & inti.
•Tdpt ribosom REK•Ribosom bebas REH
Endoplasmic Reticulum
• Smooth E.R. (no ribosomes attached), synthesizes steroids, metabolizes carbohydrates, stores calcium
• Rough E.R. (has ribosomes), manufactures proteins for secretion
Endoplasmic Reticulum
Endoplasmic reticulum (ER)
Ribosomes
• Free ribosomes (ribosomes in cytoplasm)
• Bound ribosomes (ribosomes attached to endoplasmic reticulum)
• Both carry out protein synthesis
Ribosomes
• Ribosom prokariot berukuran kecil (70S) 2 sub unit : 30S & 50S svedberg unit
• Ribosom eukariot 80S 2 sub unit 40S & 60S
REK menghasilkan protein & menyusun membran
• The rough ER manufactures membranes• Ribosomes on its surface produce proteins
1 2
3
4Transport vesiclebuds off
Ribosome
Sugarchain
Glycoprotein
Secretory(glyco-) proteininside transportvesicle
ROUGH ER
Polypeptide
Ribosomes
REH memiliki fgs bervariasi
• Smooth ER synthesizes lipids
• In some cells, it regulates carbohydrate metabolism and breaks down toxins and drugs
Golgi Apparatus
• Finish, sort, and “ship” many products of the cell
• Synthesize macromolecules• Store and export products of E.R.• Deskripsi :
Klp 5-8 kantung membran bbtk mangkuk ( cistenae ) dg ujung menggelembung & menempel satu sama lain.
Golgi Apparatus
Golgi aparatus
• Bdn golgi bbtk polar, tdr atas bagian cis dmn protein masuk, & bagian trans dmn protein keluar.
• Dibagi2 dlm kompartemen/ruang2 yg berbeda dg processing enzymes yg spesifik.
• ± tdpt 20 bdn golgi pd tiap sel, vary depending on the function of the cell
The Golgi apparatus
What does it do?
• Utk distribusi & pusat lalulintas produk kimia sel.
• Memodifikasi protein & lipid & prepares them for exportation.
• Uses sugar nucleotides to transport the proteins.
What else does it do?
• It works with the endoplasmic reticulum.
• It uses a Trans Golgi Network (TGN) to attach chemical “flags” on the exported proteins as sort of an address code so that they get to the right place in the cell.
What’s so Great about it?
• Without the Golgi Apparatus, cells could not secrete important chemicals into our bodies such as:
Hormones (to change us)Enzymes (create
chemical reactions)Antibodies ( keep us
from getting ill and possibly dying)
Lysosomes
• Digestive compartments• Digest macromolecules (protein, as. Nukleat, lipid, KH)• Digest substances ingested by phagocytosis• Membrane-bound sac filled with enzymes• pH 5 maintained by hydrogen ion pump• Manufactured by rough ER and Golgi• Fuse with food vacuoles for digestion• Can fuse with organelle or part of cytosol• Cell renewal; programmed destruction of cells during
development
Lysosomal enzymes
• 50 different degradative enzymes
• Acid hydrolases– Active at pH 5 (inside
lysosome)– Inactive if released into
cytosol (pH 7.2)
• Acidic pH of lysosomes maintained by a proton pump in the lysosomal membrane– Requires ATP
mitochondria
Products delivered to lysosomes by four routes:
• Indiscriminate Pinocytosis– Cell “drinking” < 150nm
• Receptor Mediated Endocytosis
• Phagocytosis– Cell “eating” of material >
250nm• Autophagy
– “self eat” of old worn out organelles,
– important in cell degradation during apoptosis
Lysosomes
Lysosome Lysosome pathwayspathways
Primary lysosomePrimary lysosomeBuds from trans face of GolgiBuds from trans face of Golgiexogenous materials, exogenous materials, deteriorating organellesdeteriorating organelles
Secondary lysosomeSecondary lysosomeprimary fuses with an primary fuses with an endosomeendosome or or phagosomephagosome
Usually look more electron Usually look more electron densedense
Lysosomal enzyme deficiency
Tay Sach’s Disease
• A lysosomal storage disease– Due to a mutation in
lysosomal enzymes
-N-hexosaminidase-A*• Accumulations of un-
degraded glycolipid within lysosomes
• Found in neurons of CNS(central neuro systems)
The formation and functions of lysosomes (Layer 1)
The formation and functions of lysosomes (Layer 2)
The formation and functions of lysosomes (Layer 3)
Review: relationships among organelles of the endomembrane system
Functions of endomembrane system (summary)
• Manufactures macromolecules and membranes
• Modifies macromolecules for their various functions
• Digests (hydrolyses) macromolecules
Peroxisomes
• Similar structure to lysosomes– Single membrane
• Consume oxygen – but not to form ATP as
mitochondria
• Degrades hydrogen peroxide (H2O2) – can be toxic to cells– Using catalase to degrade
hydrogen peroxide to water
Crystallineinclusion
Peroxisomes
• Consume oxygen in various metabolic functions• Bounded by a single membrane.• Spherical with a granular or crystalline core
thought to be a dense collection of enzyme molecules.
• Not formed by budding from the endomembrane system, but by using proteins and lipids made in the cytosol. Form new peroxisomes by dividing.
Peroxisomes
Peroxisomes (cont.)
• Involved in various metabolic functions, e.g. some break down fatty acids. In the liver, peroxisomes detoxify harmful compounds. Seeds have glyoxysomes.
• Peroxisomes metabolize molecules by transferring hydrogen to oxygen, producing H2O2 – hydrogen peroxide. An enzyme in the peroxisome converts this toxic by-product into water.