Grundlagen der Biologie ll: Zellbiologie
Folgt der Vorlesung Grundlagen der Biologie ll: Zellbiologie der ETZ Zürich
Folgt der Vorlesung Grundlagen der Biologie ll: Zellbiologie der ETZ Zürich
Fichier Détails
| Cartes-fiches | 26 |
|---|---|
| Langue | Deutsch |
| Catégorie | Biologie |
| Niveau | Université |
| Crée / Actualisé | 20.09.2016 / 06.10.2016 |
| Lien de web |
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Hierarchy of life
Atoms
Molecules
Macromolecules
Cellular organelles
Cells
Tissues
Organs
Organisms
Social and enviromental entities
What determines the functions and properties of a biological unit?
-Intrinsic properties
-The context
Example: Atom in a protein
The properties of an atome are determined by what type of atom it is (C, H, O,..) -->intrinsic but also by its nighboring atoms (protein folding)
Preperative Centrifugation:
Which cell compartements are gained by centrifugating at low, medium, high and ultra speed?
- At low speed: Pellet contains whole cells, nuclei, cytoskeleton
- At medium speed: Mitochondria, lysosomes, peroxisomes
- High speed: Microsomes, small vesicles
- Ultra speed: Ribosomes, viruses, large macromolecules
Chromatography strategies:
- Ion-Exchange
- Gelflitration
-Affinity (common: HIS-Tag)
Micellar concentration (CMC)
Above a criticel micellar concentration, detergents form micelles
Methods to determine protein structur:
-Crystallography
-NMR
-Electron microscopy
Translocation proteins in mitochondria
TOM/SAM-Complex: Translocation between cytosol and intermembran space
TIM22/TIM23/OXA-Complex: Translocation between intermembran space and matrix space
Organells and properties of signal sequences (location, signal removal, nature of signal)
Name mitochondrial translocation complexes and their main function:
Explain the function of hsp70
hsp70 is a chaperon protein which interacts with the hydrophobic regions in the AS sequence:
- ATP-bound hsp70 binds to target sequence
- ATP hydrolysis results in a change of conformation which clamps the hsp70 to the protein
- ATP rebinding causes dissociation from the protein
Mitochondria: Translocation into matrix
TOM --> TIM23 --> Matrix
Mitochondria: Translocation into inner membrane
TOM --> TIM23 --> lateral release
Mitochondria: Translocation into inner membrane via matrix
TOM --> TIM23 --> Matrix --> OXA
Mitochondria: Translocation of polytopic protein into inner membrane
TOM --> intra membran space with chaperons preventing folding --> TIM22
Mitochondria: Translocation into inter membran space
Mitochondria: Translocation of beta-barrels into outer membran
TOM --> inter membran space --> SAM
Lipid Bilayer
- Structurand properties of lipid molecules in the cell membrane
- Important classes of lipids
- Amphiphilic: Hydropholilc polar head and a hydrophobic non-polar tail
- Phospholipids (build from glycerol):
- Phosphatidylethanolamine (PE)
- Phosphatidylserine (PS), negatively charged
- Phosphatidylcholine (PC)
- Sphingolipids (build from sphingosine)
- Sphingomyelin (SPH)
- Sphingosine (
On what depends the lipid membran composition?
- the organism
- ambient temperature
- cell type
- membrane organelle
- lipid class
Flippases
Catalyze the rapid flip-flop of phospholipids from one mono-layer to the other
Lipid rafts
Concentration of specific membrane proteins and lipids.
- Present in the PM of eukariotic cells, Golgi and endosomes
- Induced by clustering of membrane components
- Enriched with cholesterol and sphingolipids
- Rafts form a separate phase in the membrane and serve as platforms for special functions
Endoplasmic and Exoplasmic fusion/fission
Hydrophobic effect:
- The larger the surface area of the cavity needed to fit the apolar molecule the stronger the hydrophobic effect
- Unsaturated alkyl chains are less hydrophbic than the corresponding saturated chains
- A methyl group as a branch adds less hydrophobicity, than a methyl group at the end of the chain
- Two separate chains are energetically higher than the corresponding connected chain
About the asymmetrie of the plasma membrane
- Phospholipids with a choline head group are enriched in extra-cytosolic leaflet (PC, SPH)
- Phospholipids with a terminal amino group are enriched in the cytosolic leaflet (PE, PS, PI)
- Cholesterol in both
- Glycolipids in the outer leaflet
- The asymmetrie is generated by flippases, enzymes in ER and PM which flip specific lipids
Major classes of lipids in the membrane
- Phospholipids (Subclasses: Phospholipids, Sphingolipids)
- Cholesterol
- Glycolipids
Protein mass in plasma membrane?
From 25% - 75%. It depends hugely which cell type is observed
Membran associated proteins
- Pheripheral proteins: Bound to other membran proteins or the polar heads of the phospholipids
- Intergral protein (transmembranal): hydrophobic regions pass through the membrane
- monotopic: stand out only on one side of the membrane
- bitopic: called single span proteins which have the N- and the C-termius on either side of the membrane
- polytopic: called multipass proteins
