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.
2 types of chemicals found in food.
Nutrients and xenobiotics.
Driving force of obesity increase.
Highly processed food, vegetables and fruit are more expensive, and these processed foods have longer shelf-lives.
Increases in obesity levels parallel…
Increases in disability and death, primarily due to cardiovascular diseases.
TwinX.
Twinki stuffed with Twix, wrapped in bacon, deep fried, chocolate syrup, and icing sugar; 1 100 calories with 80 grams of fat.
Risks of high sodium intake.
Hypertension.
Sugar consumption.
Sucrose consumption has been reduced, but there is increased consumption of high fructose corn syrup,
Uses of high fructose corn syrup.
You can add less to food because it tastes sweeter, easier to dissolve.
Making high fructose corn syrup.
Treat starch with enzymes that break it down into glucose units, then treat the glucose units with glucose isomerase to convert it into fructose.
Acquired metabolic syndromes are due to…
Less nutrient diversity and higher energy density in the diet.
Nutrient.
Chemical element or compound that is used in metabolic processes or is an integral component of the physiology of an organism. Can be used as energy sources, structures to build upon, or provide support.
Macronutrients.
Carbohydrates, proteins, and lipids.
Micronutrients.
Minerals, vitamins; they act as co-substrates or enzyme factors (determines enzymatic activity).
Essentiality of a nutrient.
Lack of the nutrient results in signs of deficiency, which are corrected only by the nutrient itself or a precursor for that nutrient.
Can humans make minerals?
No, not at all.
Examples of essential nutrients.
Amino acids, fatty acids, vitamins, minerals.
8 essential amino acids.
Isoleucine, leucine, lysine, metionine, phenylalanine, threonine, tryptophan, valine, histidine, and arginine (conditionally essential for growing children and disease conditions).
Essential fatty acids.
Human cannot make fatty acids with double bonds between carbons located at C8 or less (counting from the methyl end). Linoleic and linolenic acids are essential.
Fat soluble vitamins.
Vitamin A (retinol), vitamin D (ergocalciferol, cholecalciferol), vitamin E (tocopherol), vitamin K (naphthoquinoids).
Water soluble vitamins.
B1 (thiamine), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), B5 (panthothenic acid), B9 (folic acid), B12 (cobalamin), B7 (biotin), C (ascorbic acid), and choline.
Essential vitamins.
All of the B complexes, choline.
Choline.
Substrate for phosphatidylcholine synthesis, ensures structural integrity and signalling functions of the cell membrane, source of methyl groups. Can die in 24 hours without it.
Importance of phosphatidylcholine.
Found in all the cells of our body; without it, nothing would work.
Betaine.
Amino acids used to detoxify other amino acids.
Essential macrominerals.
Calcium, chloride ions, phosphorus, potassium, magnesium, and sulfur.
Essential trace minerals.
Cobalt, copper, fluoride ion, iodine, iron, manganese, nickel, sodium, selenium, zinc.
Flavonoids.
Sub-class of phytochemicals; some can be beneficial, others toxic.
Titanium dioxide.
GRAS, code is E171.
Malnutrition.
Improper or insufficient diet; nutrient deficiency and nutrient excess. Aim for a balance between deficiency and toxicity.
Essential fatty acids.
Needed for eicosanoids (prostaglandins, leukotrienes, and thromboxanes). Important in immune function, inflammatory response, blood clotting, vasodilation, kidney function, and cognitive function.
Essential fatty acid deficiency.
Can lead to growth retardation, sparse hair growth, dry skin and scaling (eczema), general weakness, depression, poor wound healing, increased susceptibility to infection, edema, and vision problems. Can also lead to neurological problems in severe cases.
Vitamin A (retinol).
Essential for maintenance of epithelial cells. Deficiency causes mucus-secreting cells to be replaced by keratin producing cells, which leads to xerosis (abnormal dryness). Teratogenic: causes malfunction in the foetus.
Ligands for retinoic acid.
RAR (retinoic acid receptor) and retinoid X receptor (RXR).
Vitamin A deficiency.
Primarily affects eye function; eye xerosis (dryness) which causes ulcerations that can lead to blindness. Associated with poor lipid absorption (fat soluble vitamin).
Vitamin A excess.
Birth defects caused during gestation period, reduced bone mineral density (risk factor for osteoporosis), weight loss, head ache, vision problems, dry itchy skin, hair loss, anemia, teeth discolouration, enlarged liver and spleen.
Iron.
Micromineral, used as a prosthetic group for many biologically important proteins: heme group of hemoglobin, myoglobin, cytochrome C, peroxidases, and hydroxylases. All enzymes dealign with oxygen have iron.
Iron metabolism.
Of the typical daily intake of 15 mg, only 2 mg of iron are absorbed. Metabolism involves many proteins.
Iron deficiency.
Causes shedding of epithelial tissue (menstruation), anemia (low blood iron).
Symptoms of anemia caused by iron deficiency.
Pale skin, tired, weakness, difficulty maintaining body temperature, shortness of breath, an inflamed tongue, diminished cognitive function, decreased immune function.
People at risk for anemia and iron deficiency.
Alcoholics, patients with infectious, inflammatory, or neoplastic diseases.
Iron excess with a genetic basis.
African hemochromatosis, porphyria, hyperferritinemia, and hemochromatosis.
Secondary hemochromatosis.
Can be caused by excessive alcohol consumption or excessive use of iron supplements; can lead to disorders like arthritis, liver disease, damage to the pancreas, which can cause diabetes, cardiac abnormalities, impotence, abnormal skin pigmentation (looks bronze), thyroid deficiency, and damage to the adrenal glands.
