Water Flashcards
What is the percentage of water in cells?
65%
What is water essential for within the body?
Hydrolysis, and the breakdown of protein and carbohydrate
Protection from UV light
Forming hydrogen bonds
What type of bonds are hydrogen bonds?
Weak, covalent bonds that exist between two electronegative atoms and an electropositive atom (dipole)
Outline the importance of hydrogen bonds
Support the structure and function of proteins, DNA, polysaccharides, enzyme-substrate bonding
Source of the unique properties of water
What is the biological relevance of hydrogen bonds?
They form between:
- hydroxyl group of alcohol and water
- carbonyl group of ketone and water
- peptide groups in polypeptides
- base pairs in DNA
Explain the relevance of the ‘cage’ that is formed in regard to salt dissolving in water
Hydrogen atoms create a cage around chemical ionisation ions
Sodium ions interact with oxygen atoms
The water surrounding the non-polar solution has a lower entropy
(The cage reduces entropy)
The lipid molecules around the cage are forced to become organised- also lowering entropy
Clustered lipids (micelle) have a lower surface area and this a higher entropy
Define entropy
Degree of Randomness
What is water a good solvent for?
Charged, polar molecules such as amino acids, peptides, carbohydrates
What is the name for the substance that dissolves into a solvent?
Solute
What is water a poor solvent for?
Non-polar substances such as non-polar gases, aromatic molecules, sterols, aliphatic chains- this is because there is no difference in electronegativity
Name a detergent that solubilises fat in water
Phosphatidylcholine
Are short and medium FA chains soluble?
Yes
Are long FA chains soluble?
No
Where do non-covenant interactions exist?
Between-
hydrogen bonds and neutral groups
peptide base
during repulsion
What are van de Waals forces?
Weak interactions between any atoms that are close together
Easily broken
