1.1 Nutrition, Diet and Body Weight Flashcards
Name the four main pathways of metabolism
- Oxidative pathways
- Fuel storage and mobilisation pathways
- Biosynthetic pathways
- Detoxification pathways
What do oxidative pathways do?
Convert food into energy
What do fuel storage & mobilisation pathways do?
Allow fuel to be mobilised when we are not eating or need increased energy
What do Biosynthetic pathways do?
Produce basic building blocks for cells
What do detoxification pathways do?
Remove toxins
What are catabolic and anabolic processes?
Catabolic processes: Break down molecules to release energy in the form of reducing power
Anabolic processes: Use energy & raw materials to make larger molecules for growth and maintenance
All living things constantly require energy for…. (5)
- 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.
Cells use ___________ energy to drive energy-requiring activities
Chemical bond
(Most convenient form of energy in the body)
(Chemical bond is in ATP)
What does an ATP molecule consist of?
- Adenine ring
- Ribose sugar
- 3 phosphates (alpha-beta-gamma)
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Which phosphate in ATP is responsible for energy production?
Gamma phosphate has phosphodiester bond that releases energy when broken to drive cellular processes
How is energy stored in the body?
Energy is stored in bonds which can potentially be broken to form ATP. (Don’t store ATP itself)
Fat (stored in adipose tissue) and glycogen (stored in liver and muscle)
Describe the ATP-ADP cycle
ATP –> ADP + Pi
The energy produced by the breakage of the phophodiester bond between the game and beta phosphate is used by:
- ion transport
- muscle contraction
- detoxification
- thermogenesis
- biosynthesis
ADP + Pi –> ATP
- Oxygen is required
Energy production by oxidation of:
- lipids
- carbohydrates
- protein
- alcohol (metabolites of alcohol cause damage)
- Carbon dioxide, water and heat are also produced
What is the official SI unit of food energy?
Kilojoules
Define 1 Kcal
Amount of energy needed to raise temperature of
one kilogram of water by one degree Celsius.
(Note: “calorie” in everyday use actually means kilocalorie
(i.e. 1000 calories)
How many kilojoules in 1Kcal?
4.2 kJ
7 food groups and what they provide
- Carbohydrate – 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
What is the general formula for carbohydrates?
(CH2O)n
Which functional groups do carbohydrates contain?
- Aldehyde
- Keto
- Multiple -OH groups
Define the categories of carbohydrates based on size and give examples for each
- Monosaccharide - single sugar units (3-9 C-atoms)
Triose sugar – 3 carbons
Pentose sugar – 5 carbons
Hexose sugar – 6 carbons e.g Glucose, C6H12O6
- Disaccharides - (2 units) e.g sucrose
- Oligosaccharides - (3 –12 units) e.g. Dextrins
- Polysaccharides (10 – 1000’s units) E.g glycogen, starch, cellulose
What are the major dietary carbohydrates? (7)
Starch (Carbohydrate storage molecule in plants. Polymer
of glucose). Alpha 1,4 glycosidic bonds between glucose monomers.
- Sucrose (Table sugar. Glucose-fructose disaccharide)
- Lactose (Milk sugar. Galactose-Glucose disaccharide)
- Fructose (Fruit sugar: Monosaccharide)
- Glucose (Predominant sugar in human blood)
- Maltose (Glucose-glucose disaccharide)
• Glycogen (Carbohydrate storage molecule in animals. Polymer of glucose)
Branches at periodic intervals - these chains are connected by alpha 1,6 glycosidic bonds
(Cellulose is a polymer of glucose found in plants )
Which process allows the conversion of carbohydrates onto something that can be absorbed into the blood?
Digestion converts larger carbohydrates to monosaccharides which are absorbed into blood
Proteins are composed of _________ joined by _________ to form _________ chains
- Amino acids
- Peptide bonds
- Linear
Digestion breaks down proteins into what? And how are these monomers used by the body?
- Digestion breaks down proteins to constituent amino acids which enter blood
- 20 different amino acids used for protein synthesis in body
- 9 Essential amino acids cannot be synthesised and must be obtained from diet
Note: Glucose can be formed from some amino acids
What are the nine essential amino acids?
Valine Leucine Isoleucine Phenylalanine Methionine Threonine Tryptophan Leucine Histidine
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When may certain amino acids be conditionally essential?
Conditionally essential = Essential when period of rapid growth
- Children
- Pregnant women