Grundlagen der Biologie ll: Zellbiologie

-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)

1. At low speed: Pellet contains whole cells, nuclei, cytoskeleton
2. At medium speed: Mitochondria, lysosomes, peroxisomes
3. High speed: Microsomes, small vesicles
4. Ultra speed: Ribosomes, viruses, large macromolecules

- Ion-Exchange

- Gelflitration

-Affinity (common: HIS-Tag)

Above a criticel micellar concentration, detergents form micelles

-Crystallography

-NMR

-Electron microscopy

TOM/SAM-Complex: Translocation between cytosol and intermembran space

TIM22/TIM23/OXA-Complex: Translocation between intermembran space and matrix space

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

TOM --> TIM23 --> Matrix

TOM --> TIM23 --> lateral release 

TOM --> TIM23 --> Matrix --> OXA

TOM --> intra membran space with chaperons preventing folding --> TIM22 

TOM --> inter membran space --> SAM

• 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 (

• the organism
• ambient temperature
• cell type
• membrane organelle
• lipid class

Catalyze the rapid flip-flop of phospholipids from one mono-layer to the other

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

• 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

• 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

• Phospholipids (Subclasses: Phospholipids, Sphingolipids)
• Cholesterol
• Glycolipids

From 25% - 75%. It depends hugely which cell type is observed

• 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