MEH - Nutrition Diet & Body Weight & Bioenergy Flashcards
What are the essential components of the diet (7)?
Protein, fats, carbohydrates, minerals, vitamins, fibre, water
What is metabolism defined as?
The chemical processes that occur within a living organism in order to maintain life
What are the 4 types of pathways of metabolism?
Oxidative - breaks down food into energy
Biosynthetic - produces basic building blocks for cells
Fuel storage and mobilisation - when not eating or need increased energy
Detoxification pathways - remove toxins e.g. CYP450s
What is energy?
The capacity to work
How is energy stored in the body? Where in ATP is where the most energy is stored?
Mainly in chemical bonds to drive energy-requiring activities. The phophodiester bond between the beta and gamma phosphates
Give 5 examples of what energy is needed for in the body?
Ion transport Muscle contraction Biosynthesis Thermogenesis Detoxification
A ‘calorie’ in everyday language is actually how much? Convert 1Kcal to kJoules
1000 calories
or 1 Kcal
1 Kcal is 4.2kJoules
What is the official SI unit of food energy?
kJ
Glucose + frutose =
Sucrose
Glucose + galactose =
Lactose
What is starch?
A polymer of glucose
Glucose + glucose =
maltose
What are the three monosaccharides?
Glucose, galactose, fructose
How many essential amino acids are there?
9
What are the 9 essential amino acids?
Isoleucine Lysine Threonine Histidine Leucine Methionine Phenylalanine Tryptophan Valine
What is a conditionally essential amino acid? Give 3 examples
AA that become essential at times where AA can’t be synthesised quick enough e.g. pregnancy so need to be in diet to supplement. Arginine, tyrosine and cysteine.
Why are proteins from plant origin considered lower quality?
As they are normally deficient in one or more essential amino acids
What is lipid composed of?
Three triacylglycerols (Fatty acids) esterified to one glycerol
What is the difference in the structure between saturated and unsaturated fats?
Saturated - no double bonds - solid at room temp
Unsaturated - has one or more double bonds - liquid at room temp
Why does fat release more energy when oxidised compared to carbs or protein?
Because it has less oxygen (so is more reduced) than carbs or protein.
What vitamins are fat-soluble, so require fat intake?
ADEK
What are the two primary essential fatty acids? Why are these essential?
Linoleic and Linolenic acids (Omega 6 and 3). As they cannot be synthesised in the body
Why do we need intake of minerals e.g. electrolytes
To maintain ion gradients across membranes and maintain water balance
Why do we need intake of minerals e.g. calcium and phosphorus?
For bones and teeth
Ca also important for signalling
Why do we need intake of minerals e.g. iron manganese, cobalt, copper, zinc, and molybdenum?
They are enzyme cofactors
Why do we need intake of minerals e.g. iron?
Essential for Hb synthesis
Are vitamins essential for life? What happens in folate deficiency for example?
Yes. Anaemia, neural tube defects in foetus
Why does dietary fibre reduced atherosclerosis?
Because fibre sequesters bile salts and excretes them. Bile salts are used normally to make cholesterol
Can fibre be broken down by human enzymes? Give 4 examples of fibres
No.
Cellulose, Lignin, Pectins, Gums
What do starch, glycogen and cellulose all have in common?
They are polymers of glucose
Why can’t humans break down cellulose?
Don’t have the enzymes to break the beta 1-4 glycosidic bonds
Low fibre intake is associated with _____ and ______ ______
Constipation and bowel cancer
What is the normal daily energy expenditure for M/F and what 3 things is it the sum of?
M - 12,000kJ/day
F - 9500kJ/day
Sum of:
Basal metabolic rate
Diet-induced thermogenesis
Physical activity level
Broadly what does basal metabolic rate do? What three functions in the body does it have?
Maintains resting activities of the body
1) Maintenance of cells e.g. ions across membranes
2) Function of organs
3) Maintaining body temp
Which organs/tissues take up a large % of BMR?
Skeletal muscle - 30%
Liver - 20%
Brain - 20%
Heart - 10%
State 5 factors that affects BMR
- Gender
- Body size
- Cold temp increases
- Endocrine (e.g. hyperthyroidism)
- Body temp
What is the equation for BMI and figures for Underweight, normal, overweight, obese, severely obese. What is the weakness with BMI?
BMI = weight/height2 (Kg/m2). Underweight - Below 18.5 Normal over 18.5 Overweight over 25 Obese over 30 Severely obese over 35
Very muscular may be wrongly classified as obese
What happens in protein deficiency disease Kwashiorkor?
Low protein diet leads to low protein in blood (e.g. albumin), reduced oncotic pressure, so oedema around abdomen.
Does exergonic require energy? What would the gibbs free energy be?
No releases it
Less than 0
Does endergonic require energy?
Yes requires it
More than 0
What is a H carrier molecule?
When fuel molecules are oxidised, protons and electrons are transferred to carrier molecules
What are 3 major carrier molecules in their oxidised or reduced forms?
Oxidised Reduced
NAD+ NADH
NADP+ NADPH
FAD FADH2
What is the role of carrier molecules? What role does NADH and NADPH have?
Act as carriers of reducing power.
NADH - ATP synthesis
NADPH - biosynthesis
When converting carrier molecules to reduced form, how many H+ atoms are added?
2
What is a reducing equivalent?
A species which transfer the equivalent of one electron in redox reactions (i.e. a lone e- or H+ atom [contains a proton and electron])
How can reducing equivalents be used to drive energy requiring activities in the body?
Either directly: NADPH - Biosynthesis
Or indirectly - via coupling NADH to ATP synthesis
Catabolic pathways are activated by (low/high) energy signals e.g. (4)
Low energy signals (oxidised forms of)
ADP/AMP
NAD+
NADP+
FAD
How is excess energy stored in the body? What is the relevance of creatine phosphate? Where is the energy in creatine phosphate?
Normally as glycogen or fat stores
Skeletal muscle needs to mobilise fuel quickly so haas a store of creatine phosphate. Energy is stored in the phosphate bond.
