4 Sugars, lipids and cellular barriers Flashcards
Carbohydrate group
CH2O
Sugars - role of 5C
DNA / RNA / ATP
Sugars - role of 6C
Energy roles and structure
Alpha glucose polymers (3)
amylose (1,4)
amylopectin (1,4 1,6)
glycogen (1,4 1,6)
Beta glucose polymer
cellulose (1,4)
Chitin
N-acetyl glucosamine
Glycobiology - where do glycans attach
Glycans attatched to the asn, ser, the = glycoproteins
Glycan roles - structural
mucous proteins (glycans containing sialic acid)
Glycan roles - functional
ABO blood groups —> glycans attatched to cell surface proteins + lipids
Glycan roles - proteoglycans
important features of extracellular environemnt - forms collagen / structural bases that holds cells and tissues into place / shock absorbing / lubrications
What is the extracellular matrix rich in (ECM)
Glycans
Lipids - fats, oils and waxes
More reduced than carbohydrates - more efficient energy store (larger energy release)
Trans-fats
more similar to saturated fats although theyre unsaturated C=C
Phospholipids
2FA and a phosphate group attatched to an alcohol - the alcohol is often charged) has a polar and charged end VS the unipolar uncharged FA end
Lipid head (hydrophilic) faces out and FA tail (hydrophobic) faces inwards
The first cells
Inside and outside - fatty acids may be available on the early earth
Eukaryotic cells
Specialisations help them to grow large and complex
Energy - mitochondria (and chloroplasts)
Complex internal and external membranes
Sophisticated transport systems and internal skeleton (cytoskeleton)
Membrane structure
flexibility and fluidity (yet strong)
Fluid mosaic model - lipids and membrane proteins can move in the plane of the membrane. Fluidity can be affected by temperature and unsaturation
Membrane composition varies between species and between membranes within a cell - bacterial cells are the most uniform and have the highest proportion of PtdEtn (PtdEtn is responsible for the maintenance of mitochondrial integrity and assembly of lactose permease and other membrane proteins)
Membrane composition can vary as follows…
Inner and outer face can vary (eg. animal cells plasma membrane)
Cytoplasmic face + Extracellular face
Mechanism for ‘flipping’ phospholipids
Cholesterol in membranes
moderator of membrane fluidity (adding cholesterol fills in some of the gaps and makes the membrane less fluid
Led to the idea of Lipid rafts (self organised regions of membrane)
Proteins in membranes
Transmembrane domains (intergration proteins)
Peripheral proteins (can be anchored to a phospholipid - only present on one side —> GPI anchor is a linkage via a phospholipid)
