Carbohydrate, fat and protein Flashcards
Carbs
- composition
- Carbon
- Hydrogen
- Oxygen
Carbs
- general formula
(CH2O)n
Types of carbs
- Monosaccharides
- Oligosaccharides
- Polysaccharides
Monosaccharides
Basic unit of carbohydrates
Oligosaccharides
2 - 10 sugars bonded chemically
(disaccharides most common) - sucrose
Polysaccharides
3 to thousands of sugars linked together
Monosaccharides
- Types
- Glucose
- Fructose
- Galactose
Glucose
Blood sugar
Fructose
fruit sugar (sweet tasting sugar)
Galactose
Does not exist free in nature
-High Glycaemic index
Disaccharides
- Lactose = Glucose + Galactose
- Sucrose = Glucose + Fructose
- Maltose = Glucose + Glucose
Lactose
- Least sweet sugar
- Milk
Sucrose
- Most common sugar
- Honey, cane sugar
- maple syrup
Maltose
Beer, breakfast cereal
Plant polysaccharides
- Starch
- Fibre
Starch
- 80-90% of all polysaccharides we eat
- Lower glycaemic index
- Most important source of carbs (AKA complex carbs) - Amylose, amylopectin
- Found in seeds, corn, grains of cereal etc.
Fibre
- Non-starch, structural polysaccharide
- Found in legumes, some fruits, juices and certain veg
Role of CHO
- Energy source
- Catabolism of blood glucose and glycogen from liver and muscles fuels muscle contraction
- Fuel for the central nervous system
Lipids
- Structure
Same structural components as carbohydrates
Hydrogen to oxygen ratio
High
Types of Lipids
- Simple
- Compound
- Derived
Simple lipids
- Most common
Triacylglycerols
- Made up of 3 fatty acids and a glycerol
- Main form of fat in adipocytes
- One of the most important forms of dietary fat
Fat energy density
Fat is energy-dense, get more energy from 1g of fat than 1g of carbs
Types of fatty acid
- Saturated
- Unsaturated
Saturated fatty acids
Only single covalent bonds between carbon atoms
Unsaturated fatty acids
one or more double bonds along their main carbon chain
What are compound lipids
Triacyglycerol components combined with other chemicals
What are derived lipids
Substances derived from simple and compound lipids
Example of derived lipid
Cholestral
Cholestral
- Classified as lipid
- Both Exogenous and endogenous
- Builds plasma membranes
- Synthesises vitamins, hormones and bile
- High levels are predictor of coronary artery disease
Role of fat in the body
- Energy source and reserve
- Structural ( membranes)
- Protection of vital organs
- Thermal insulation
- Vitamin carrier
- Hunger depresser
What do proteins contain
- Carbon
- Hydrogen
- Nitrogen
- Oxygen
- Amino acids - Amine group, organic acid group, R group or sidechain
Recommended dietary protein intake
15% of total energy intake
When increase protein intake
- Infants and growing children
- Vegetarians
Role of protein in the body
Amino acids are major building blocks for synthesising tissue
what does protein act as in the body
- Enzyme
- Hormone
- Structural
- Muscle protein
- Energy source
How does protein act as an energy source in the body
It is converted to glucose in the liver to provide energy for the brain when CHO intake is low
