Lipids and Cell Membranes Flashcards
What are some examples of lipids?
1- Phospholipids
2- Fats
3- Sterols
4- Some vitamins
What is the solubility of lipids in water
Very low
What are the roles of lipids?
1- Sources of energy
2- Forming membranes
3- Participating in cell signalling
Describe the structure of fatty acids.
1- Carboxyl group with a long hydrocarbon chain
2- CH3(CH2)4-24COOH (CH2 anywhere between 2 to 24)
3- All naturally occuring fatty acids have an even number of carbons
How are fatty acids acquired into the body?
1- Short and medium chains are absorbed into the blood stream
2- Long chains cannot be absorbed so they are synthesised
In respect to the ratio of carbon bonds to double bonds, what are the three types of fatty acids?
1- Saturated (16:0)
2- Unsaturated (18:1)
3- Polyunsaturated (20:4)
What are examples of sterols?
1- Bile acids
2- Steroid hormones
3- Vitamins
4- Cell membranes
What type of lipid is cholesterol?
Sterol
What is Gaucher’s disease?
1- Inherited disorder
2- Affects lipid pathways
3- Accumulation of glucocerebrocide
How do disorders which affect the lipid pathway affect the body?
1- Lipid accumulation 2- Affect neurological system 3- Enlarged liver and spleen 4- Enlarged bone marrow cavities 5- Failure to thrive
Which three groups of lipids are found in the membrane?
1- Phospholipids
2- Glycolipids
3- Sterols
Describe the structure of a phospholipid.
1- Polar head group
2- Glycerol backbone
3- Fatty acid chains (usually two)
What are five examples of phospholipids?
1- Choline 2- Ethanolamine 3- Serine 4- Glyerol 5- Inositol
Describe the structure of a glycolipid.
1- Sphingosine backbone
2- Fatty acid chain
3- Attached to CH R group
What is an amphipathic compound?
A molecule with a hydrophilic head and a hydrophobic tail
How are double bonds labelled in a fatty acid chain?
By delta 1….2….3 etc
What structure is specific to cholesterol?
3 6-sided ring and 1 5-ring of carbon atoms
Describe the lipid bilayer.
1- Biylayer of phospholipids
2- Hydrophilic heads point outwards and are attracted to water
3- Hydrophobic tails point inwards and seek to aggregate with other, hydrophobic molecules
4- Contain lipids which help contribute to membrane strength and stability
Why are membranes important?
1- Compartmentalisation, separating cell from outside
2- Compartmentalisation, separating organelles
3- Have highly selective barriers to control entry and exit
4- Have sensors which respond to internal and external conditions to help the cell act accordingly
What are the two classes of proteins in the membrane?
1- Peripheral (extrinsic) proteins
2- Integral (intrinsic) proteins
In what ways can phospholipids move within the membrane?
Membrane is extremely fluid
1- Lateral movement: very frequent, 10^7 per second
2- Flip-flop: very rare, may happen ~once per month
What is the difference of the structure of phospholipids between fluid and viscous membranes?
1- Fluid membranes have phosphilipids with unsaturated hydrocarbon tails with kinks
2- Viscous membranes have phospholipids with saturated hydrocarbon tails with no kinks
Describe the structure of cholesterol.
1- Polar head group
2- Rigid, planar steroid ring structure
3- Nonpolar hydrocarbon tail
How does the cholesterol molecule fit in the phospholipid membrane?
1- Polar head next to hydrophobic phospholipid heads
2- Rigid, planar steroid ring structure next to proximal tail to stiffen the region
3- Nonpolar hydrocarbon tail next to distal tail, more fluid than proximal tail
