basic nutrition Flashcards
what are the 2 categories differentiating nutrients?
essential vs. non-essential nurtients
macro vs. micronutrients
what characterises essential nutrients?
and what are some examples of them?
cannot be synthesised, or not in sufficient quantities (created) by the body
e.g vitamins, minerals, essential fatty and amino acids
what characterises non-essential nutrients?
and what are some examples of them?
can be made and in sufficient quantities by the body
e.g non essential fatty and amino acids and glucose
what characterises macronutrients?
and what are some examples of them?
usually required in gram qunatities (macro = large)
quantitatively largest part of diet
e.g carbohydrate, fat, protein, water and alcohol
what characterises micronutrients?
and what are some examples of them?
usually needed in small amounts (less than a gram as micro = small)
quantitatively largest family of nutrients
e.g vitamins, minerals and trace-elements
what are trace-elements?
a chemical element required only in minute amounts for normal growth
e.g iron
what elements are carbohydrates made up of?
what are carbohydrates?
what is the formula which all carbohydrates follow?
carbon, hydrogen and oxygen
they are hydrated carbons (hence made up of H, O and C)
multiples of CH2O
what are monosaccharides?
Monosaccharides are the simplest units of carbohydrates and the simplest form (monomer) of sugar
soluble in water
e.g glucose, fructose and galactose
what are disaccharides?
A disaccharide is the sugar formed when two monosaccharides are joined by glycosidic linkage
soluble in water
e.g sucrose and maltose
what are polysaccharides?
long chain of monosaccharides
insoluble in water due to size
e.g starch
what are the 3 types of carbohydrate?
mono, di and poly saccharides
what is the most common sugar in the body?
glucose
what is the most common type of carbohydrate in the diet?
sucrose
what are some of the properties of triacylglycerol?
contain 3 fatty acids attached to a molecule of glycerol (CHO)
comprises 95% of dietary fats
concentrated source of energy
stored within adipose tissue as insulating layer
intake and absorption of fat soluble vitamins
what does ‘n’ mean when referring to fatty acids?
number of carbons from methyl end
what does it mean if a fatty acid is
saturated?
monounsaturated?
polyunsaturated?
saturated - 0 double bonds (so solid at room temp)
monounsaturated - 1 double bond (liquid at room temp)
polyunsaturated - more than 1 double bond (liquid at room temp)
what are phospholipids?
broadly?
structurally?
specific function?
a type of fat (eggs)
2 hydrophobic fatty acids tails and a hydrophilic ‘polar head’ group (phosphate group) joined together by a glycerol molecule
amphipathic acting as interface between aqueous and lipid environments so essential structural component of cell memebrane (phospholipid bilayer)
what does it mean when describing phospholipids as ‘amphipathic’?
it has both hydrophilic (head) and hydophobic (tails) parts
what is a bilayer?
film 2 molecules thick in which eah molecule has hydrophobic end directed inwards and hydrophilic end directed outwards
what are sterols?
a type of fat
main sterol = cholesterol (food of animal origin)
arranged in a ring structure with associated side chains
plays key role in membrane structure, synthesis of hormones and bile acids
what does synthesis mean?
the production of chemical compounds by reactoion from simpler materials
how can nitrogen be used to calculate protein requirements?
majority of nitrogen excreted in urine as urea
describe dietary proteins
structurally?
chemically?
functions?
composed of C,H,O,S and N
made up of amino acids in polypeptide chains
used for promotion of growth and development: energy, structural material for tissues, enzymes etc.
how is quality of protein measured?
what is the threshold for good quality protein?
on digestibility and nitrogen retention
retained / absorbed x 100
above 70 reflects protein quality sufficient to maintain growth (more use from amino acids and less excreted nirtogen in urea)
which nutrients are responsible for resisting and fighting an infection?
vitamins, minerals and protein
which nutrients are responsible for the provision of energy, warmth and movement?
carbohydrates and fats
which nutrients are required to regulate metabolism?
proteins (enzymes), vitamins and minerals
what is the definition of a food ‘requirement’?
minimum amount of a nutrient needed to sustain a physiological state, function or structure of an organism
how many nutrients are recognised as being in a healthy diet?
40
what is the Estimated Average Requirement?
notional mean requirement of normal distribution of amount of a nutrient
what is Reference Nutrient Intake?
2 standard deviations above the EAR (mean)
what is the Lower Reference Nutrient Intake?
2 standard deviatins below the EAR (mean) and intakes below this line are likely deficient
what are DRVs?
how may they be developed?
dietary reference values which assess requirements of nutrients
can be judged by e.g:
intake needed to cure signs of deficiency and maintain balance
what is the nitrogen balance?
amount of protein taken in = amount of nitrogen leaving the body
what are the rough percentages of different food groups in the modern diet?
fat - 40%
starch - 30%
sugar - 20%
protein - 12%
how and where do we store fat, carbs and protein?
protein - no storage area as it’s all functional
fat - triglyceride in adipose tissue
carbohydrate - glycogen in muscles and liver
how are the dissacharides lactose, maltose and sucrose formed?
all formed by 2 monosaccharides
sucrose = glucose + fructose lactose = glucose + galactose maltose = glucose + glucose
where would you find oligosaccharides?
lentils
which tissue has the highest and lowest protein turnover rates?
highest - blood plasma
lowest - muscle
