Water Flashcards
(34 cards)
What is water a good solvent for?
Charged or polar substances
amino acids, carbohydrates
What is water a poor solvent for?
Non polar substances (aromatic moieties, aliphatic chains)
What are aromatic moieties?
Aromatic = substances that consist of one or more rings that contain alternating single and double bonds Moieties = branches in organic molecules that extend from the carbon backbone
What is an example of an aromatic moiety?
Sterols
What is an aliphatic chain?
Chains with a high density of carbons and hydrogens
What is an example of an aliphatic chain?
Long chain fatty acids
What type of bond is a hydrogen bond?
Non covalent
How strong are hydrogen bonds?
Fairly weak
What is the distance of a hydrogen bond?
Roughly the same as a carbon carbon bond
What type of molecules do hydrogen bonds form between?
Electronegative atom and a hydrogen bonded to another electronegative atom
When are hydrogen bonds strong and weak?
Strong - when all 3 components are in a line
Weak - when the hydrogen bond is formed on an angle
What are the importance of hydrogen bonds?
DNA structure Protein structure Polysaccharide structure Properties of water Binding of substrates to enzymes Binding of hormones to receptors Matching mRNA and tRNA
What is a detergent?
A substance that solubilises fats in water
Name 4 non-covalent bonds.
Hydrogen
Ionic
Hydrophobic interactions
Van de Waals interactions
What are hydrophobic interactions?
The tendency of non polar molecules and non polar components of molecules to interact with each other when in a polar solvent
What are Van de Waals interactions?
Induced electrical interactions between two or more molecules that are very close together
What happens when salt is dissolved in water?
Cl- interacts with the positively charged hydrogen
Na+ interacts with the negatively charged oxygen
What is entropy?
The degree of disorder or randomness in a system
What is the hydrophobic effect?
Water in the presence of clusters of lipids has a higher entropy than that of water in the presence of individually dispersed lipids
What are micelles?
lipid molecules that arrange themselves in a spherical form in aqueous solutions
What does the hydrophobic effect favour?
Ligand binding
What are ligands?
Molecules which produce a signal by binding to target proteins
What happens when a cell is placed in an isotonic solution?
No net movement
What happens when a cell is placed in a hypotonic solution?
Net movement into the cell
