Nutrients Flashcards
Why do all water molecules have hydrogen bonding?
The unequal sharing of electrons in a water molecule results in the oxygen having a partial negative charge, while the hydrogen has a partial positive charge
List all the properties of water
Good solvent: mineral salts and food transported while dissolved in plants, blood plasma in humans
Cohesion (btw water molecules) and Adhesion (with other molecules): transpiration pull
High heat of vaporisation: evaporative cooling, sweating
Reactant: raw material for photosynthesis and hydrolysis of food during digestion
Incompressible: provides turgor pressure, amniotic fluid protects foetus
High specific heat capacity: allows large bodies of water to maintain relatively constant temperatures despite surrounding changes
State all monosaccharides, disaccharides and polysaccharides and their components
Monosaccharides: glucose, fructose, galactose
Disaccharides—
Sucrose: fructose + glucose
Lactose: glucose + galactose
Maltose: glucose
Polysaccharides: starch, cellulose, glycogen
Composition of carbohydrates
Carbon, hydrogen, oxygen (H:O=2:1)
What are carbon molecules in glucose used for?
Synthesis of other molecules like amino acids or fatty acids
Reactions for nutrients (hydrolysis and condensation)
Hydrolysis (digestion): 1 large molecule + water = many small molecules
Condensation: many small molecules = 1 large molecule + water
Water is a raw material in hydrolysis (large to small), but a product in condensation (small to large)
What is the bond in disaccharides and triglycerides?
Disaccharides: covalent, glycosidic linkage
Triglycerides: 3 ester bonds/linkages between glycerol and fatty acids
Describe the structure of polysaccharides
Starch and cellulose and linear, but cellulose is alternate. Glycogen is branched
Functions of all carbohydrates
Glucose: raw material of respiration
Starch (in plants) and glycogen (in animals): large and insoluble storage materials (polysaccharides)
Cellulose: structural material in plants, makes up the cell wall
Deoxyribose and ribose sugars: makes up DNA and mRNA
What are lipids (triglycerides) and its composition
One glycerol molecule joined to 3 fatty acids: carbon, hydrogen, oxygen
What has more oxygen in proportion to hydrogen?
Lipids not saccharides
Hydrolysis of triglycerides
Each triglyceride can be hydrolysed into 1 glycerol and 3 fatty acids by the enzyme lipase
What are saturated and unsaturated fats?
Saturated fats have the maximum possible amount of hydrogen molecules and are solid at rtp.
Unsaturated fats have less than the maximum possible amount of hydrogen molecules and are liquid at rtp
Functions and types of lipids
Storage molecules, insulating material, steroid and some hormone synthesis, solvent for fat-soluble vitamins
Types: phospholipids, steroids, carotenoids
Structure (subunits of proteins) of amino acids
Alpha carbon (C) connected to: Side chain (R) Animo group (H-N-H) Carbonyl group (O=C-OH)
How many types of and elements in animo acids
Twenty types, depending on the R group
Elements found: carbon, hydrogen, oxygen, nitrogen, (sulphur)
Hydrolysis of proteins
Protein + water (catalysed by protease) = amino acids
Function of proteins
Enzymes (biological catalysts), antibodies, haemoglobin, collagen (structural), hormones (eg. insulin, glucagon)
Structure and conformation of proteins, and their denaturisation
Polypeptide chains in unique 3D conformation (amino acid sequence determines protein type). Bonds between amino acids are strong, bonds that hold structure together are weak.
Due to extreme temperature or pH, permanent.
What has a lower proportion of hydrogen, phospholipids or carbohydrates?
Phospholipids molecule, not carbohydrates
Food test for starch
Add a few drops of iodine solution to the test sample.
Positive: iodine solution changes from brown to blue-black
Negative: iodine solution remains brown
Food test for reducing sugars (Benedict’s test)
Reducing sugars are all disaccharides and polysaccharides except for sucrose.
Place 2cm^3 of food sample in a test tube
Add 2cm^3 of Benedicts solution to the food sample and mix
Heat in a boiling water bath for 2-3 minutes
Positive: mixture changed from blue to red/orange/yellow/green (different concentration = range of colours)
Negative: mixture remains blue
Food test for non-reducing sugars (polysaccharides and sucrose)
Boil food sample with hydrochloric acids, causing the hydrolysis of the glycosidic bond in the non-reducing sugar if present
Carry out Benedict’s test
Place 2cm^3 of food sample in a test tube
Add 2cm^3 of Benedicts solution to the food sample and mix
Heat in a boiling water bath for 2-3 minutes
Positive: mixture changed from blue to red/orange/yellow/green (different concentration = range of colours)
Negative: mixture remains blue
Food test for proteins (Biuret test)
Add 2cm^3 of NaOH (sodium hydroxide) to 2cm^3 of the food sample and shake thoroughly.
Add 1% copper sulfate solution dropwise, shaking after every drop
Positive: mixture changed from blue to VIOLET
Negative: mixture remains blue
