Lipids 1 Flashcards
Structure of membranes?
Sheet like, two molecules thick, form closed boundaries between different compartments
What are membrane lipids?
Small molecules that have both hydrophilic and hydrophobic moieties. They spontaneously form lipid bilayers that are a barrier to the flow of polar molecules
What do membranes consist of?
Lipids and proteins, also carbohydrates
What regulates the functions of membranes?
Specific proteins
How are proteins and lipids held together?
By non covalent interactions which act cooperatively
Symmetry of membranes?
Asymmetric- two faces of biological membranes differ
Fluidity of membranes?
Very fluid as there is a rapid diffusion of lipids in the plane of the membrane- although they do not readily rotate across
Polarity of membrane?
Most cell membranes are electrically polarised, eg the inside is typically negative
Four major roles of fatty acids?
- Are building blocks of phospholipids and glycolipids
- Proteins are modified by the covalent attachment of fatty acid
- Are fuel molecules
- Derivatives of fatty acids serve as hormones and intracellular messengers
What are fatty acids stored as?
Triacylglycerols (uncharged esters of fatty acids with glycerol)
What are saturated fatty acids?
Only single bonds in the fatty acid
What are unsaturated fatty acid?
At least one double bone on the fatty acid
Stereochemistry of double bond in unsaturated fatty acid?
Cis
What is oleate?
A monosaturated fatty acid : 18:1 cis-9
Do fatty acids vary in chain length and degree of unsaturation?
Yes
16 carbon fatty acid?
Palmitate; CH2(CH2)14COO-
18 carbon fatty acid?
Stearate ; CH3(CH2)18COO-
What are essential fatty acids?
Fatty acids we can’t make
What is a trans isomer implicates in?
Disease
But what is the benefit of a cis changing to a trans isomer?
More stable, lower energy confirmation
What diet is cardiovascular disease correlates with?
A diet high in saturated fat
What are vegetable oils high in and what are they prone to?
Polyunsaturated far- prone to oxidation and instability
What happens to polyunsaturated fats to make then more stable/less prone to oxidation?
They’re hydrogenated, converted to saturated and trans unsaturated fatty acids (trans fat) which will also convert liquid into a solid
What do epidemiological evidence appear to support?
Consumption of large amounts of saturated fats and trans fats promote heart disease
