1.5 Principles of human nutrition Flashcards
What is metabolism?
The ensemble of catabolism and anabolism.
Tightly regulated by homes such as insulin and glucagon that regulate blood sugar levels, or growth hormone
What is catabolism?
Chemical reaction that provides nutrients for the body to use
What is anabolism?
Chemical reaction that provides energy storage when the body has enough energy.
What are the 6 categories of nutrients?
Sugars, proteins, fats, vitamins, minerals and water
What are macronutrients?
Chemical elements consumed in large quantities are used to generate energy and/or are involved in growth or repair
What are micronutrients?
Chemical elements are required in small amounts. Important in human metabolism, acting as coenzymes or cofactors
Examples of macronutrients
Carbohydrates, proteins, lipids and water
Calcium, sodium, potassium, potassium, etc
Examples of micronutrients
Vitamins such as zinc, copper, iodine
What are essential nutrients?
Essential nutrients are found in the diet and cannot be made from other molecules in the body.
How many amino acids are essential out of the 20 in the body?
9 are essential; 2 fatty acids are essential; vitamins are also essentials and some minerals also play crucial roles in maintaining homeostasis
What are non-essential nutrients?
Non-essential nutrients can be made from food or are synthesised through metabolic/ enzymatic reactions
What are the main characteristics of carbohydrates?
- Main sources of energy. Essential for cell function.
- Readily available and release energy is fast
- Not the most efficient in terms of energy production (4 Kcal/g)
What are monosaccharides?
Single units of carbohydrates they cannot be further digested or hydrolysed.
What are the examples of monosaccharides?
Molecules of glucose, fructose and galactose
What are oligosaccharides?
Carbohydrate chain made of more than 3 monosaccharides
What is a triose?
Any group of monosaccharides that contain 3 carbons
What is a 5-carbon ring sugar called?
Ribose
What are hexoses?
6- carbon sugars.
They are either ketoses (contain a ketone group) or aldoses (contain an aldehyde group)
What are hemi-acetal structures?
Sugars with at least 5 carbons easily form ring structures
What are disaccharides?
Form when two monosaccharides combine
What are examples of disaccharides?
Maltose (glucose+glucose), sucrose (glucose+fructose) and lactose (glucose+galactose)
Are disaccharides soluble?
Yes
What are polysaccharides?
When more than 10 units are combined.
What are polysaccharides?
When more than 10 units are combined.
What are examples of polysaccharides?
Starch, glycogen and cellulose
What is a homopolysaccharide?
A polysaccharide containing only one type of monosaccharide
What is a heteropolysaccharide?
A polysaccharide that contains different types of monosaccharides
How is amylopectin formed?
Alpha 1-6 glycosidic bonds
What are glycoaminoglycans?
Combine polysaccharides and proteins and are a part of the cell membrane
What are lipids?
Heterogeneous group of compounds including, fatty acids (saturated or unsaturated), triglycerides, phospholipids, ketone bodies.
What are the functions of lipids?
Metabolic messengers, regulators, providing some cushioning for internal organs or insulation, absorb lipid-soluble vitamins
What is the structure of a fatty acid?
Fatty or hydrophobic carbon chain ending with an acidic COOH group
What are saturated fatty acids?
All C-C bonds are single covalent bonds
What are unsaturated fatty acids?
One or more C-C bonds are double
What are cis-polyunsaturate fatty acids?
Bent configuration. Important for the good function of cell membranes.
What are trans-fatty acids?
Hydrogen atoms on opposite sides of the carbon, making the molecule more linear. Present in dairy products and hydrogenated oils
What is glycerol?
Glycerol is a 3-carbon type of alcohol. It has a hydroxyl group.
What are proteins?
Structural elements of the cell: enzymes, hormones, receptors, channels, etc
What are essential proteins?
Amino acids which can’t be created in our body but can only be received from proper food or diet
What are non-essential proteins?
Bodies can produce the amino acid, even if we do not get it from the food we eat.
What is the structure of a protein?
Carboxylic acid group: COOH and an amine group NH2. Hence proteins have an N-terminal and a C-terminal
R group defines the amino acid and the group can be non-polar, polar, acidic or basic
What is a protein made of?
Combination of amino acids linked by peptide bonds
What are the three structures of proteins?
- Primary structure: sequence of amino acids
- Secondary structure: arrangement of protein chains
- Tertiary structure: folding into a globular shape (enzymes, immunoglobins).Protein folding results from three different structural elements beyond primary structure.
- Quaternary structure: more than one protein chain (Insulin (and pro-insulin) and haemoglobin)
What is glycogenesis?
The synthesis of glycogen molecules from glucose units mostly in liver, small amount in skeletal muscle
What is lipogenesis?
Synthesis of triglycerides by combining fatty acids and glycerol molecules
Some fatty acids will be used to produce ATP via beta-oxidation and the excess will be re-combined with molecules of glycerol and stored as triglycerides
What is gluconeogenesis?
Production of glucose from endogenous metabolites: pyruvate (lactate), glycerol and some amino acids (alanine and glutamine) in the liver
What are the pathways involved in carbohydrate, lipid and protein metabolism?
Step 1: Digestion of sugars, lipids and proteins into monosaccharides, fatty acids+ glycerol and amino acids
Step 2: further degradation leading to pyruvate and acetylCoA which are essential molecules for the production of ATP.
Monosaccharides undergo glycolysis (creating pyruvate), fatty acids undergo beta-oxidation (producing acetylCoA), amino acids can be converted or degraded into various metabolites but only under conditions such as starvation
Step 3: Kreb’s cycle in mitochondria (main ATP production site)
