1 - Water and Carbohydrates Flashcards
What is a monomer?
Smaller units from which larger molecules are made
Structure of water?
Covalent bonds between oxygen and hydrogen and a difference in electronegativity - polar molecule with partial positive and partial negative charge This means there is hydrogen bonding between the molecules.
How is water good at keeping a constant body temperature?
High specific heat capacity
How does water cool an organism?
Has a high latent heat of vaporisation, meaning when we sweat and the water evaporates off our skin, there is a cooling effect as the average kinetic energy of the water molecules is lowered.
What is a solvent?
A liquid in which other substances can dissolve
What is a solute?
A molecule that can dissolve in a liquid
Water as a solvent?
The charged regions of water separate molecules and allow them to move freely. Means water is good for metabolic reactions and for transporting substances (such as in the blood)
What is surface tension and cohesion?
- Hydrogen bonding between molecules means that water sticks together in a column
- When there is no water molecule above another, the uneven distribution of attraction forms a thin ‘skin’ layer called surface tension - Can support insects and small aquatic creatures
What do carbohydrates contain?
Carbon, hydrogen and oxygen Cx(H2O)y
What are the monosaccharides?
Simple sugars
- glucose
- fructose
- galactose
What are the disaccharides?
Double sugars
- glucose + glucose –> maltose
- glucose + fructose –> sucrose
- glucose + galactose –> lactose
What are the polysacchardies?
Large molecules form many monosaccarhides
- Starch
- Glycogen
- Cellulose
Glucose
C6H12O6 (Hexose sugar)
Energy source
Alpha glucose –> OH below carbon
Beta glucose –> OH above carbon
Ribose and deoxyribose
Deoxyribose has no OH on its second carbon
How are disaccharides formed?
Condensation reaction between two monosaccharides
- Forms disaccharide and H20
- OH and HO are broken to form bond with oxygen remaining
- 1,4 glycosidic bond
Structure of starch
Polysaccharide
Made from only Alpha glucose
Contains amylose (unbranched) - good because compact - and amylopectin (branched) - glycosidic bonds broken down easily - glucose released quickly
Both alpha 1,4 and alpha 1,6 glycosidic bonds
Used for Energy store in plants
Insoluble in water - good for storage as it does not alter osmosis
Cellulose
Polysaccharide Found in plant cell walls Long chains of Beta glucose molecules Beta glucose 1,4 glycosidic bonds Chains for microfibrils in a layered network Joins in condensation reaction where every other Beta glucose is rotated 180 degrees Forms glycosidic bond at oxygen on top Extra strength because of hydrogen bonds
Glycogen
Polysaccharide Animal energy store Alpha 1,6 and 1,4 glycosidic bonds Branched structure - Good for storage Less dense and more soluble than starch and broken down more rapidly - higher metabolic rate in animals
Test for reducing sugars
Add Benedict's reagent (solution) (Blue) Heat sample - bring to boil (Water bath) Observe for colour change/ coloured precipitate Qualitative test Blue - none Green/ yellow - low conc Orange - med conc Red - high conc More accurate way is to filter and weigh Always use an excess to make sure all the sugar reacts
Test for non reducing sugars
Add HCl Boil for 5 mins Add NaHCO3 Add Benedict's Reagent (solution) Heat Observe for colour change Qualitative test Blue - none Green/ yellow - low conc Orange - med conc Red - high conc
What are Polymers?
Large, complex molecules composed of long chains of monomers
Test for starch
Add iodine dissolved in potassium iodide solution - if starch present then changes from browny-orange to a dark, blue-black colour
Importance of water?
Metabolite
Solvent
Temperature control
Very cohesive - water transport in plants
How to produce a calibration curve and find the concentration of (reducing sugars)?
Produce benedicts test for known concentrations of sugars
Use calorimeter to find colour intensity and plot on a calibration curve
Find the concentration of sample from calibration curve
