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
What is plant oil made from?
55-83% oleic oil 18:1
Liquid at room temperature
What is animal fat?
Saturated fatty acids
Solid at room temperature
What is the process of hydrogenation?
Increased MP of fats (to spreads)
Addition of H atoms to polyunsat vegetable oils to semi solid/solid
Partial control; H2/temperature/time
Three major kinds of membrane lipids? (Structural lipids)
Phospholipids
Glycolipids
Cholesterol
What is the major class of membrane lipids?
Phospholipids
What four components make up a phospholipid?
One or more fatty acids
A platform to which fatty acids are attached
Phosphate
An alcohol attached to the phosphate
What can the platform on which a phospholipid can be built called?
Glycerol
3 carbon alcohol or sphingosine
More complex alcohol
What is a phospholipid derived from glycerol called?
Phosphoglycerides
What is it called when no further additions are made to the resulting compound, and what amount are present in membranes?
Phosphatidate
How are major phosphoglycerides derived from phosphatidate?
By the formation of an ester bond between the phosphate group of phosphatidate and hydroxyl group of one of servers alcohols
Two types of phospholipids?
Phosphatidylserine
Phosphatidylcholine
What are the name of some membrane lipids that include carbohydrate moieties?
Glycolipids
Example of a glycolipids?
Cerebroside
What is cholesterol?
A lipid based on a steroid nucleus
What anchor to membranes through covalently attached lipid anchors?
Some proteins
When can soluble proteins associate with membranes?
If hydrophobic groups are attached to proteins
What proteins are common anchoring proteins?
N-myristoyl and s-palmitoyl
What if a potential therapeutic application regarding membranes?
Lipid vesicles or liposomes
