What is energy?
Energy is the capacity to do work
Which five cellular processes occuring in living things require energy to occur?
- Biosynthetic work – synthesis of cellular components
- Transport work – movement of ions & nutrients across membranes
- Mechanical work – muscle contraction
- Electrical work – nervous conduction
- Osmotic work – kidney
Illustrate the ADP-ATP cycle in terms of energy usage and energy production
What is the unit of food energy?
Kilojoule (kJ) is official SI unit of food energy
What is a Kcal and how many kJ are found in it?
1 Kcal = amount of energy needed to raise temperature of one kilogram of water by one degree Celsius
1 kcal = 4.2 Kilojoules
In terms of nutrition, identify the 7 possible nutrients obtained and the respective functions of each
- Carbohydrates – mostly supplies energy
- Protein – energy and amino acids
- Fat – energy and essential fatty acids
- Minerals – essential
- Vitamins – essential
- Water – maintains hydration
- Fibre – necessary for normal GI function
Identify the two types of essential components of the diet
Identify some macronutrients
Identify some micronutrients
Describe the molecular structure of carbohydrates
General formula (CH2O)n
- Contain aldehyde (-C=OH) or keto (-C=O) group
- Multiple –OH groups
Describe the molecular structure of the following carbohydrate units:
- Monosaccharides: single sugar units (3-9 C-atoms)
- Disaccharides: two sugar units
- Oligosaccharides: 3-12 units e.g. dextrins
- Polysaccharides: 10-1000’s units e.g. glycogen, starch, cellulose
Identify and describe the seven major dietary carbohydrate molecules
- Glucose: predominant sugar in human blood
- Maltose: glucose-glucose disaccharide
- Fructose: fruit sugar (monosaccharide)
- Sucrose: table sugar (glucose-fructose disaccharide)
- Lactose: milk sugar (galactose-glucose disaccharide)
- Starch: carbohydrate storage molecule in plants (polymer of glucose)
- Glycogen: carbohydrate storage molecule in animals (polymer of glucose)
Describe the molecular structure of proteins
Proteins are composed of amino acids joined to form linear chains
20 different amino acids used for protein synthesis in body. However, 9 amino acids cannot be synthesised and must be obtained from diet.
Identify the essential amino acids
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Arginine is a conditionally essential amino acid.
What does that mean?
- Arginine can be synthesised in the body
- A dietary supply needed only during periods of active growth e.g pregnancy
Tyrosine is a conditionally essential amino acid.
What does it mean?
- Tyrosine can be synthesised in the body from phenylaline
- Essential only if the diet is low in phenylaline
Cysteine is a conditionally essential amino acid.
What does this mean?
- Cysteine can be synthesised in the body from methionine
- Essential only if the diet is low in methionine
In terms of high quality and lower quality proteins, explain why the vegetarian diet must obtain protein from a wide variety of plant sources
- Protein of animal origin considered “high quality” and contain all essential amino acids
- Proteins of plant origin generally considered “lower quality” since most are deficient in one or more essential amino acids
Describe the molecular structure of lipids
Lipids are composed of triacylglycerols (3 fatty acids esterified to one glycerol
Provide four reasons as to why lipids are important to the diet
- Greater energy yield than carbs (2x)
- Absorption of fat soluble vitamins
- Structural components of the cell membranes
- Provides essential fatty acids e.g. linoleic and linolenic acids
Briefly explain the role of vitamins in the body
- Vitamins are essential for life and required in micro- or milligram quantities
- Deficiency diseases occur if inadequate intake
Identify 4 fat soluble vitamins as well as their associated deficiency diseases
- Vitamin A – xerophthalmia
- Vitamin D – rickets
- Vitamin E – neurological abnormalities
- Vitamin K – defective blood clotting
Identify 6 water soluble vitamins as well as their associated deficiency diseases
- Vitamin C (ascorbic acid) – scurvy
- Vitamin B1 (thiamin) – beriberi
- Vitamin B2 (riboflavin) – ariboflavinosis
- Vitamin B3 (niacin) – pellagra
- Vitamin B6 – dermatitis, anaemia
- Vitamin B12 – anaemia
What is the function of minerals in the body?
Electrolytes establish ion gradients across membranes & maintain water balance
Identify 5 major minerals in the body
- Na (Sodium)
- K (Potassium)
- Ca (Calcium)
- Cl (Chlorine)
- P (Phosphorous)
Identify 5 trace elements in the body
- Fe (Iron)
- Zn (Zinc)
- I (Iodine)
- Cu (Copper)
- Mn (Manganese)
What is dietary fibre and why is it important?
- Fibre is non-digestible plant material found in cereal foods e.g. bread, beans, fruit, veg
- Needed for normal bowel function
Describe the consequences of low fibre and high fibre diets respectively
- Low fibre intake associated with constipation and bowel cancer
- High fibre diet shown to reduce cholesterol and risk of diabetes
What is the daily energy expenditure for an average male and female respectively?
- Energy expenditure of 70 kg male = `12 000 kJ
- Energy expenditure of 58 kg female = `9 500 kJ
Which factors affect the energy requirements in individuals?
- Body composition
- Physical activity