Lecture 3 Flashcards
Environment-genome interaction.
Genes control the metabolism of nutrients; nutrients influence the expression of genes.
Phenylketonuria (PKU).
Normally, phenylalanine is made into tyrosine, an important component of neurotransmitters. Some people have a mutation in phenylalanine hydroxylase (missing the enzyme). This causes an increase in phenylalanine concentration in the brain, hindering glycolysis, neurotransmitter synthesis, etc. Results in a cognitive deficiency in neurophysiological and neuropsychological dysfunction.
How sweet is aspartame relative to normal sugar?
200 times sweeter than sucrose.
Under which code is aspartame added to foods?
E951.
If something is labelled as sugar free, which sugar is often present?
Aspartame.
Fatty acid components.
Polar head group (glycerol) and hydrocarbon tails that contain a carboxyl group and a methyl group.
What determines the properties of a fatty acid?
Saturation.
What determines the shape of a fatty acid?
Saturation.
Why is the shape of a fatty acid important?
Important for the receptors and important as bio-actors (they signal pathways and receptors).
Olive oil and safflower oil.
Higher level of unsaturation, bent shape so you cannot pack them. Olive oil is rich in oleic acid. Safflower oil is rich in linoleic acid.
Lard and beef tallow.
Unsaturated: they can be packed, so they can from solid fats. Rich in palmitic (C16:0) and stearic (C18:0) acids.
Importance of solid fats.
Texture, helps a product keep its shape, more palatable, keeps for longer (longer shelf-life).
Which type of fatty acid has a longer shelf life: saturated or unsaturated?
Highly saturated.
Hydrogenation.
Vegetable fatty acids are converted from unsaturated to saturated; becomes a solid. May result in trans fat. Example: margarine.
Trans fatty acids.
A double bind remains after hydrogenation (incomplete). Trans fats have a bent shape and cannot be metabolized.
Coconut oil.
Unsaturated, more medium chain fatty acids. Easy to metabolize because medium chain fatty acids can be metabolized directly in the liver. High saturated fat: risk for cardiovascular disease. No longer recommended for consumption.
Uses of fatty acids.
Energy source, structural component (phospholipids in the cell membrane), substrates for signal molecule synthesis, and covalent modification of proteins.
Which process creates hydrophobic proteins?
Myristoylation.
In which form do we store fatty acids?
Triglycerides.
Phospholipid.
A phosphate binds to the R group of a fatty acid.
Micelle.
One fatty acid.
Phospholipid bilayer.
2 fatty acids.
Saturation of myristic acid.
Completely saturated.
Dietary sterols.
Active and important. Structure: 4 rings (core ) and an OH group at C3. Partially absorbable sterols are from animal sources; poorly absorbable sterols are from plant sources.
Cholesterol.
Cannot be metabolized or oxidized (does not give energy), waxy substance, synthesized by animal cells, requires HMG-CoA reductase for its synthesis, requires energy to synthesize, and it is the precursor of highly reactive bio-molecules.
Uses of cholesterol in the body.
Substrate for the synthesis of steroid hormones and vitamin D, substrate for the synthesis of bile acids, and required for control of membrane fluidity.
How is cholesterol stored?
Esterified to fatty acids.